Robert W Schoenlein

All Publications

• Uncovering the 3d and 4d Electronic Interactions in Solvated Ru Complexes with 2p3d Resonant Inelastic X-ray Scattering. Inorganic chemistry Poulter, B. I., Biasin, E., Nowak, S. H., Kroll, T., Alonso-Mori, R., Schoenlein, R. W., Govind, N., Sokaras, D., Khalil, M. 2023

  Abstract

  The electronic structure and dynamics of ruthenium complexes are widely studied given their use in catalytic and light-harvesting materials. Here we investigate three model Ru complexes, [RuIII(NH3)6]3+, [RuII(bpy)3]2+, and [RuII(CN)6]4-, with L3-edge 2p3d resonant inelastic X-ray scattering (RIXS) to probe unoccupied 4d valence orbitals and occupied 3d orbitals and to gain insight into the interactions between these levels. The 2p3d RIXS maps contain a higher level of spectral information than the L3 X-ray absorption near edge structure (XANES). This study provides a direct measure of the 3d spin-orbit splittings of 4.3, 4.0, and 4.1 eV between the 3d5/2 and 3d3/2 orbitals of the [RuIII(NH3)6]3+, [RuII(bpy)3]2+, and [RuII(CN)6]4- complexes, respectively.

  View details for DOI 10.1021/acs.inorgchem.3c00919

  View details for PubMedID 37314410

• Revealing core-valence interactions in solution with femtosecond X-ray pump X-ray probe spectroscopy. Nature communications Weakly, R. B., Liekhus-Schmaltz, C. E., Poulter, B. I., Biasin, E., Alonso-Mori, R., Aquila, A., Boutet, S., Fuller, F. D., Ho, P. J., Kroll, T., Loe, C. M., Lutman, A., Zhu, D., Bergmann, U., Schoenlein, R. W., Govind, N., Khalil, M. 2023; 14 (1): 3384

  Abstract

  Femtosecond pump-probe spectroscopy using ultrafast optical and infrared pulses has become an essential tool to discover and understand complex electronic and structural dynamics in solvated molecular, biological, and material systems. Here we report the experimental realization of anultrafast two-color X-ray pump X-ray probe transient absorption experiment performed in solution. A 10fs X-ray pump pulse creates a localized excitation by removing a 1s electron from an Fe atom in solvated ferro- and ferricyanide complexes. Following the ensuing Auger-Meitner cascade, the second X-ray pulse probes the Fe 1s3p transitions in resultant novel core-excited electronic states. Careful comparison of the experimental spectra with theory, extracts +2eV shifts in transition energies per valence hole, providing insight into correlated interactions of valence 3d with 3p and deeper-lying electrons. Such information is essential for accurate modeling and predictive synthesis of transition metal complexes relevant for applications ranging from catalysis to information storage technology. This study demonstrates the experimental realization of the scientific opportunities possible with the continued development of multicolor multi-pulse X-ray spectroscopy to study electronic correlations in complex condensed phase systems.

  View details for DOI 10.1038/s41467-023-39165-2

  View details for PubMedID 37291130

• Precise dd excitations and commensurate intersite Coulomb interactions in the dissimilar cuprates YBa2Cu3O7-y and La2-xSrxCuO4 PHYSICAL REVIEW B Huang, S., Wray, L., Shao, Y., Wu, C., Wang, S., Lee, J., Chen, Y., Schoenlein, R. W., Mou, C. Y., Chuang, Y., Lin, J. 2023; 107 (13)

  View details for DOI 10.1103/PhysRevB.107.134513

  View details for Web of Science ID 000974672600002

• Femtosecond X-ray Spectroscopy Directly Quantifies Transient Excited-State Mixed Valency. The journal of physical chemistry letters Liekhus-Schmaltz, C., Fox, Z. W., Andersen, A., Kjaer, K. S., Alonso-Mori, R., Biasin, E., Carlstad, J., Chollet, M., Gaynor, J. D., Glownia, J. M., Hong, K., Kroll, T., Lee, J. H., Poulter, B. I., Reinhard, M., Sokaras, D., Zhang, Y., Doumy, G., March, A. M., Southworth, S. H., Mukamel, S., Cordones, A. A., Schoenlein, R. W., Govind, N., Khalil, M. 1800: 378-386

  Abstract

  Quantifying charge delocalization associated with short-lived photoexcited states of molecular complexes in solution remains experimentally challenging, requiring local element specific femtosecond experimental probes of time-evolving electron transfer. In this study, we quantify the evolving valence hole charge distribution in the photoexcited charge transfer state of a prototypical mixed valence bimetallic iron-ruthenium complex, [(CN)5FeIICNRuIII(NH3)5]-, in water by combining femtosecond X-ray spectroscopy measurements with time-dependent density functional theory calculations of the excited-state dynamics. We estimate the valence hole charge that accumulated at the Fe atom to be 0.6 ± 0.2, resulting from excited-state metal-to-metal charge transfer, on an 60 fs time scale. Our combined experimental and computational approach provides a spectroscopic ruler for quantifying excited-state valency in solvated complexes.

  View details for DOI 10.1021/acs.jpclett.1c03613

  View details for PubMedID 34985900

• Following Metal-to-Ligand Charge-Transfer Dynamics with Ligand and Spin Specificity Using Femtosecond Resonant Inelastic X-ray Scattering at the Nitrogen K-Edge. The journal of physical chemistry letters Jay, R. M., Eckert, S., Van Kuiken, B. E., Ochmann, M., Hantschmann, M., Cordones, A. A., Cho, H., Hong, K., Ma, R., Lee, J. H., Dakovski, G. L., Turner, J. J., Minitti, M. P., Quevedo, W., Pietzsch, A., Beye, M., Kim, T. K., Schoenlein, R. W., Wernet, P., Fohlisch, A., Huse, N. 2021: 6676-6683

  Abstract

  We demonstrate for the case of photoexcited [Ru(2,2'-bipyridine)3]2+ how femtosecond resonant inelastic X-ray scattering (RIXS) at the ligand K-edge allows one to uniquely probe changes in the valence electronic structure following a metal-to-ligand charge-transfer (MLCT) excitation. Metal-ligand hybridization is probed by nitrogen-1s resonances providing information on both the electron-accepting ligand in the MLCT state and the hole density of the metal center. By comparing to spectrum calculations based on density functional theory, we are able to distinguish the electronic structure of the electron-accepting ligand and the other ligands and determine a temporal upper limit of (250 ± 40) fs for electron localization following the charge-transfer excitation. The spin of the localized electron is deduced from the selection rules of the RIXS process establishing new experimental capabilities for probing transient charge and spin densities.

  View details for DOI 10.1021/acs.jpclett.1c01401

  View details for PubMedID 34260255

• Ultrafast x-ray pump x-ray probe transient absorption spectroscopy: A computational study and proposed experiment probing core-valence electronic correlations in solvated complexes. The Journal of chemical physics Liekhus-Schmaltz, C. E., Ho, P. J., Weakly, R. B., Aquila, A., Schoenlein, R. W., Khalil, M., Govind, N. 2021; 154 (21): 214107

  Abstract

  Femtosecond x-ray pump-x-ray probe experiments are currently possible at free electron lasers such as the linac coherent light source, which opens new opportunities for studying solvated transition metal complexes. In order to make the most effective use of these kinds of experiments, it is necessary to determine which chemical properties an x-ray probe pulse will measure. We have combined electron cascade calculations and excited-state time-dependent density functional theory calculations to predict the initial state prepared by an x-ray pump and the subsequent x-ray probe spectra at the Fe K-edge in the solvated model transition metal complex, K4FeII(CN)6. We find several key spectral features that report on the ligand-field splitting and the 3p and 3d electron interactions. We then show how these features could be measured in an experiment.

  View details for DOI 10.1063/5.0047381

  View details for PubMedID 34240961

• Using X-ray free-electron lasers for spectroscopy of molecular catalysts and metalloenzymes NATURE REVIEWS PHYSICS Bergmann, U., Kern, J., Schoenlein, R. W., Wernet, P., Yachandra, V. K., Yano, J. 2021

  View details for DOI 10.1038/s42254-021-00289-3

  View details for Web of Science ID 000630688500001

• Revealing the bonding of solvated Ru complexes with valence-to-core resonant inelastic X-ray scattering CHEMICAL SCIENCE Biasin, E., Nascimento, D. R., Poulter, B. I., Abraham, B., Kunnus, K., Garcia-Esparza, A. T., Nowak, S. H., Kroll, T., Schoenlein, R. W., Alonso-Mori, R., Khalil, M., Govind, N., Sokaras, D. 2021; 12 (10): 3713–25

  View details for DOI 10.1039/d0sc06227h

  View details for Web of Science ID 000630166700031

• Author Correction: Direct observation of coherent femtosecond solvent reorganization coupled to intramolecular electron transfer. Nature chemistry Biasin, E., Fox, Z. W., Andersen, A., Ledbetter, K., Kjar, K. S., Alonso-Mori, R., Carlstad, J. M., Chollet, M., Gaynor, J. D., Glownia, J. M., Hong, K., Kroll, T., Lee, J. H., Liekhus-Schmaltz, C., Reinhard, M., Sokaras, D., Zhang, Y., Doumy, G., March, A. M., Southworth, S. H., Mukamel, S., Gaffney, K. J., Schoenlein, R. W., Govind, N., Cordones, A. A., Khalil, M. 2021

  View details for DOI 10.1038/s41557-021-00663-9

  View details for PubMedID 33627886

• Direct observation of coherent femtosecond solvent reorganization coupled to intramolecular electron transfer. Nature chemistry Biasin, E., Fox, Z. W., Andersen, A., Ledbetter, K., Kjar, K. S., Alonso-Mori, R., Carlstad, J. M., Chollet, M., Gaynor, J. D., Glownia, J. M., Hong, K., Kroll, T., Lee, J. H., Liekhus-Schmaltz, C., Reinhard, M., Sokaras, D., Zhang, Y., Doumy, G., March, A. M., Southworth, S. H., Mukamel, S., Gaffney, K. J., Schoenlein, R. W., Govind, N., Cordones, A. A., Khalil, M. 2021

  Abstract

  It is well known that the solvent plays a critical role in ultrafast electron-transfer reactions. However, solvent reorganization occurs on multiple length scales, and selectively measuring short-range solute-solvent interactions at the atomic level with femtosecond time resolution remains a challenge. Here we report femtosecond X-ray scattering and emission measurements following photoinduced charge-transfer excitation in a mixed-valence bimetallic (FeiiRuiii) complex in water, and their interpretation using non-equilibrium molecular dynamics simulations. Combined experimental and computational analysis reveals that the charge-transfer excited state has a lifetime of 62fs and that coherent translational motions of the first solvation shell are coupled to the back electron transfer. Our molecular dynamics simulations identify that the observed coherent translational motions arise from hydrogen bonding changes between the solute and nearby water molecules upon photoexcitation, and have an amplitude of tenths of angstroms, 120-200cm-1 frequency and ~100fs relaxation time. This study provides an atomistic view of coherent solvent reorganization mediating ultrafast intramolecular electron transfer.

  View details for DOI 10.1038/s41557-020-00629-3

  View details for PubMedID 33589787

• Excited-State Charge Distribution of a Donor-π-Acceptor Zn Porphyrin Probed by N K-Edge Transient Absorption Spectroscopy. The journal of physical chemistry letters Cordones, A. A., Pemmaraju, C. D., Lee, J. H., Zegkinoglou, I. n., Ragoussi, M. E., Himpsel, F. J., de la Torre, G. n., Schoenlein, R. W. 2021: 1182–88

  Abstract

  Zinc porphyrin solar cell dyes with donor-π-acceptor architectures combine light absorber (π), electron-donor, and electron-acceptor moieties inside a single molecule with atomic precision. The donor-π-acceptor design promotes the separation of charge carriers following optical excitation. Here, we probe the excited-state electronic structure within such molecules by combining time-resolved X-ray absorption spectroscopy at the N K-edge with first-principles time-dependent density functional theory (TD-DFT) calculations. Customized Zn porphyrins with strong-donor triphenylamine groups or weak-donor tri-tert-butylbenzene groups were synthesized. Energetically well-separated N K-edge absorption features simultaneously probe the excited-state electronic structure from the perspectives of the macrocycle and triphenylamine N atoms. New absorption transitions between the macrocycle N atoms and the excited-state HOMO vacancy are observed, and the triphenylamine associated absorption feature blue-shifts, consistent with partial oxidation of the donor groups in the excited state.

  View details for DOI 10.1021/acs.jpclett.0c03725

  View details for PubMedID 33480697

• Double core hole valence-to-core x-ray emission spectroscopy: A theoretical exploration using time-dependent density functional theory. The Journal of chemical physics Zhang, Y., Bergmann, U., Schoenlein, R., Khalil, M., Govind, N. 2019; 151 (14): 144114

  Abstract

  With the help of newly developed X-ray free-electron laser (XFEL) sources, creating double core holes (DCHs) simultaneously at the same or different atomic sites in a molecule has now become possible. DCH X-ray emission is a new form of X-ray nonlinear spectroscopy that can be studied with a XFEL. Here, we computationally explore the metal K-edge valence-to-core (VtC) X-ray emission spectroscopy (XES) of metal/metal and metal/ligand DCH states in a series of transition metal complexes with time-dependent density functional theory. The simulated DCH VtC-XES signals are compared with conventional single core hole (SCH) XES signals. The energy shifts and intensity changes of the DCH emission lines with respect to the corresponding SCH-XES features are fingerprints of the coupling between the second core hole and the occupied orbitals around the DCHs that contain important chemical bonding information of the complex. The difference between delocalized/localized core hole models on DCH VtC-XES is also briefly discussed. We theoretically demonstrate that DCH XES provides subtle information on the local electronic structure around metal centers in transition metal complexes beyond conventional linear XES. Our predicted changes from calculations between SCH-XES and DCH-XES features should be detectable with modern XFEL sources.

  View details for DOI 10.1063/1.5111141

  View details for PubMedID 31615256

• Using Ultrafast X-ray Spectroscopy To Address Questions in Ligand-Field Theory: The Excited State Spin and Structure of [Fe(dcpp)(2)](2+) INORGANIC CHEMISTRY Britz, A., Gawelda, W., Assefa, T. A., Jamula, L. L., Yarranton, J. T., Galler, A., Khakhulin, D., Diez, M., Hardee, M., Doumy, G., March, A., Bajnoczi, E., Nemeth, Z., Papai, M., Rozsalyi, E., Szemes, D., Cho, H., Mukherjee, S., Liu, C., Kim, T., Schoenlein, R. W., Southworth, S. H., Young, L., Jakubikova, E., Huse, N., Vanko, G., Bressler, C., McCusker, J. K. 2019; 58 (14): 9341–50

  Abstract

  We have employed a range of ultrafast X-ray spectroscopies in an effort to characterize the lowest energy excited state of [Fe(dcpp)2]2+ (where dcpp is 2,6-(dicarboxypyridyl)pyridine). This compound exhibits an unusually short excited-state lifetime for a low-spin Fe(II) polypyridyl complex of 270 ps in a room-temperature fluid solution, raising questions as to whether the ligand-field strength of dcpp had pushed this system beyond the 5T2/3T1 crossing point and stabilizing the latter as the lowest energy excited state. Kα and Kβ X-ray emission spectroscopies have been used to unambiguously determine the quintet spin multiplicity of the long-lived excited state, thereby establishing the 5T2 state as the lowest energy excited state of this compound. Geometric changes associated with the photoinduced ligand-field state conversion have also been monitored with extended X-ray absorption fine structure. The data show the typical average Fe-ligand bond length elongation of ∼0.18 Å for a 5T2 state and suggest a high anisotropy of the primary coordination sphere around the metal center in the excited 5T2 state, in stark contrast to the nearly perfect octahedral symmetry that characterizes the low-spin 1A1 ground state structure. This study illustrates how the application of time-resolved X-ray techniques can provide insights into the electronic structures of molecules-in particular, transition metal complexes-that are difficult if not impossible to obtain by other means.

  View details for DOI 10.1021/acs.inorgchem.9b01063

  View details for Web of Science ID 000475838000051

  View details for PubMedID 31241335

• UV-Photochemistry of the Disulfide Bond: Evolution of Early Photoproducts from Picosecond X-ray Absorption Spectroscopy at the Sulfur K-Edge JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Ochmann, M., Hussain, A., von Ahnen, I., Cordones, A. A., Hong, K., Lee, J., Ma, R., Adamczyk, K., Kim, T., Schoenlein, R. W., Vendrell, O., Huse, N. 2018; 140 (21): 6554–61

  Abstract

  We have investigated dimethyl disulfide as the basic moiety for understanding the photochemistry of disulfide bonds, which are central to a broad range of biochemical processes. Picosecond time-resolved X-ray absorption spectroscopy at the sulfur K-edge provides unique element-specific insight into the photochemistry of the disulfide bond initiated by 267 nm femtosecond pulses. We observe a broad but distinct transient induced absorption spectrum which recovers on at least two time scales in the nanosecond range. We employed RASSCF electronic structure calculations to simulate the sulfur-1s transitions of multiple possible chemical species, and identified the methylthiyl and methylperthiyl radicals as the primary reaction products. In addition, we identify disulfur and the CH2S thione as the secondary reaction products of the perthiyl radical that are most likely to explain the observed spectral and kinetic signatures of our experiment. Our study underscores the importance of elemental specificity and the potential of time-resolved X-ray spectroscopy to identify short-lived reaction products in complex reaction schemes that underlie the rich photochemistry of disulfide systems.

  View details for DOI 10.1021/jacs.7b13455

  View details for Web of Science ID 000434101100010

  View details for PubMedID 29771112

• Transient metal-centered states mediate isomerization of a photochromic rutheniumsulfoxide complex NATURE COMMUNICATIONS Cordones, A. A., Lee, J., Hong, K., Cho, H., Garg, K., Boggio-Pasqua, M., Rack, J. J., Huse, N., Schoenlein, R. W., Kim, T. 2018; 9: 1989

  Abstract

  Ultrafast isomerization reactions underpin many processes in (bio)chemical systems and molecular materials. Understanding the coupled evolution of atomic and molecular structure during isomerization is paramount for control and rational design in molecular science. Here we report transient X-ray absorption studies of the photo-induced linkage isomerization of a Ru-based photochromic molecule. X-ray spectra reveal the spin and valence charge of the Ru atom and provide experimental evidence that metal-centered excited states mediate isomerization. Complementary X-ray spectra of the functional ligand S atoms probe the nuclear structural rearrangements, highlighting the formation of two metal-centered states with different metal-ligand bonding. These results address an essential open question regarding the relative roles of transient charge-transfer and metal-centered states in mediating photoisomerization. Global temporal and spectral data analysis combined with time-dependent density functional theory reveals a complex mechanism for photoisomerization with atomic details of the transient molecular and electronic structure not accessible by other means.

  View details for PubMedID 29777157

• Comprehensive Experimental and Computational Spectroscopic Study of Hexacyanoferrate Complexes in Water: From Infrared to X-ray Wavelengths JOURNAL OF PHYSICAL CHEMISTRY B Ross, M., Andersen, A., Fox, Z. W., Zhang, Y., Hong, K., Lee, J., Cordones, A., March, A., Doumy, G., Southworth, S. H., Marcus, M. A., Schoenlein, R. W., Mukamel, S., Govind, N., Khalil, M. 2018; 122 (19): 5075–86

  Abstract

  We present a joint experimental and computational study of the hexacyanoferrate aqueous complexes at equilibrium in the 250 meV to 7.15 keV regime. The experiments and the computations include the vibrational spectroscopy of the cyanide ligands, the valence electronic absorption spectra, and Fe 1s core hole spectra using element-specific-resonant X-ray absorption and emission techniques. Density functional theory-based quantum mechanics/molecular mechanics molecular dynamics simulations are performed to generate explicit solute-solvent configurations, which serve as inputs for the spectroscopy calculations of the experiments spanning the IR to X-ray wavelengths. The spectroscopy simulations are performed at the same level of theory across this large energy window, which allows for a systematic comparison of the effects of explicit solute-solvent interactions in the vibrational, valence electronic, and core-level spectra of hexacyanoferrate complexes in water. Although the spectroscopy of hexacyanoferrate complexes in solution has been the subject of several studies, most of the previous works have focused on a narrow energy window and have not accounted for explicit solute-solvent interactions in their spectroscopy simulations. In this work, we focus our analysis on identifying how the local solvation environment around the hexacyanoferrate complexes influences the intensity and line shape of specific spectroscopic features in the UV/vis, X-ray absorption, and valence-to-core X-ray emission spectra. The identification of these features and their relationship to solute-solvent interactions is important because hexacyanoferrate complexes serve as model systems for understanding the photochemistry and photophysics of a large class of Fe(II) and Fe(III) complexes in solution.

  View details for DOI 10.1021/acs.jpcb.7b12532

  View details for Web of Science ID 000432754100013

  View details for PubMedID 29613798

• Nonlinear Ultrafast Spin Scattering in the Skyrmion Phase of Cu2OSeO3 PHYSICAL REVIEW LETTERS Langner, M. C., Roy, S., Huang, S. W., Koralek, J. D., Chuang, Y., Dakovski, G. L., Turner, J. J., Robinson, J. S., Coffee, R. N., Minitti, M. P., Seki, S., Tokura, Y., Schoenlein, R. W. 2017; 119 (10): 107204

  Abstract

  Ultrafast x-ray scattering studies of the topological Skyrmion phase in Cu_{2}OSeO_{3} show the dynamics to be strongly dependent on the excitation energy and fluence. At high photon energies, where the electron-spin scattering cross section is relatively high, the excitation of the topological Skyrmion phase shows a nonlinear dependence on the excitation fluence, in contrast to the excitation of the conical phase which is linearly dependent on the excitation fluence. The excitation of the Skyrmion order parameter is nonlinear in the magnetic excitation resulting from scattering during electron-hole recombination, indicating different dominant scattering processes in the conical and Skyrmion phases.

  View details for DOI 10.1103/PhysRevLett.119.107204

  View details for Web of Science ID 000409560100006

  View details for PubMedID 28949160

• The Linac Coherent Light Source: Recent Developments and Future Plans APPLIED SCIENCES-BASEL Schoenlein, R. W., Boutet, S., Minitti, M. P., Dunne, A. M. 2017; 7 (8)

  View details for DOI 10.3390/app7080850

  View details for Web of Science ID 000408905900100

• Picosecond sulfur K-edge X-ray absorption spectroscopy with applications to excited state proton transfer STRUCTURAL DYNAMICS Van Kuiken, B. E., Ross, M. R., Strader, M. L., Cordones, A. A., Cho, H., Lee, J., Schoenlein, R. W., Khalil, M. 2017; 4 (4): 044021

  Abstract

  Picosecond X-ray absorption (XA) spectroscopy at the S K-edge (∼2.4 keV) is demonstrated and used to monitor excited state dynamics in a small organosulfur molecule (2-Thiopyridone, 2TP) following optical excitation. Multiple studies have reported that the thione (2TP) is converted into the thiol (2-Mercaptopyridine, 2MP) following photoexcitation. However, the timescale and photochemical pathway of this reaction remain uncertain. In this work, time-resolved XA spectroscopy at the S K-edge is used to monitor the formation and decay of two transient species following 400 nm excitation of 2TP dissolved in acetonitrile. The first transient species forms within the instrument response time (70 ps) and decays within 6 ns. The second transient species forms on a timescale of ∼400 ps and decays on a 15 ns timescale. Time-dependent density functional theory is used to identify the first and second transient species as the lowest-lying triplet states of 2TP and 2MP, respectively. This study demonstrates transient S K-edge XA spectroscopy as a sensitive and viable probe of time-evolving charge dynamics near sulfur sites in small molecules with future applications towards studying complex biological and material systems.

  View details for DOI 10.1063/1.4983157

  View details for Web of Science ID 000402004800022

  View details for PubMedID 28529962

  View details for PubMedCentralID PMC5422206

• Light-Induced Radical Formation and Isomerization of an Aromatic Thiol in Solution Followed by Time-Resolved X-ray Absorption Spectroscopy at the Sulfur K-Edge JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Ochmann, M., von Ahnen, I., Cordones, A. A., Hussain, A., Lee, J., Hong, K., Adamczyk, K., Vendrell, O., Kim, T., Schoenlein, R. W., Huse, N. 2017; 139 (13): 4797–4804

  Abstract

  We applied time-resolved sulfur-1s absorption spectroscopy to a model aromatic thiol system as a promising method for tracking chemical reactions in solution. Sulfur-1s absorption spectroscopy allows tracking multiple sulfur species with a time resolution of ∼70 ps at synchrotron radiation facilities. Experimental transient spectra combined with high-level electronic structure theory allow identification of a radical and two thione isomers, which are generated upon illumination with 267 nm radiation. Moreover, the regioselectivity of the thione isomerization is explained by the resulting radical frontier orbitals. This work demonstrates the usefulness and potential of time-resolved sulfur-1s absorption spectroscopy for tracking multiple chemical reaction pathways and transient products of sulfur-containing molecules in solution.

  View details for DOI 10.1021/jacs.6b12992

  View details for Web of Science ID 000398764000032

  View details for PubMedID 28219243

• Prominent role of oxygen in the multiferroicity of DyMnO3 and TbMnO3: A resonant soft x-ray scattering spectroscopy study PHYSICAL REVIEW B Huang, S. W., Lee, J. M., Jeng, H., Shao, Y., Wray, L., Chen, J. M., Qiao, R., Yang, W. L., Cao, Y., Lin, J., Schoenlein, R. W., Chuang, Y. 2016; 94 (3)

  View details for DOI 10.1103/PhysRevB.94.035145

  View details for Web of Science ID 000380100500001

• Electronic and Molecular Structure of the Transient Radical Photocatalyst Mn(CO)(5) and Its Parent Compound Mn-2(CO)(10) INORGANIC CHEMISTRY Cho, H., Hong, K., Strader, M. L., Lee, J., Schoenlein, R. W., Huse, N., Kim, T. 2016; 55 (12): 5895–5903

  Abstract

  We present a time-resolved X-ray spectroscopic study of the structural and electronic rearrangements of the photocatalyst Mn2(CO)10 upon photocleavage of the metal-metal bond. Our study of the manganese K-edge fine structure reveals details of both the molecular structure and valence charge distribution of the photodissociated radical product. Transient X-ray absorption spectra of the formation of the Mn(CO)5 radical demonstrate surprisingly small structural modifications between the parent molecule and the resulting two identical manganese monomers. Small modifications of the local valence charge distribution are decisive for the catalytic activity of the radical product. The spectral changes reflect altered hybridization of metal-3d, metal-4p, and ligand-2p orbitals, particularly loss of interligand interaction, accompanied by the necessary spin transition due to radical formation. The spectral changes in the manganese pre- and main-edge region are well-reproduced by time-dependent density functional theory and ab initio multiple scattering calculations.

  View details for DOI 10.1021/acs.inorgchem.6b00208

  View details for Web of Science ID 000378369900025

  View details for PubMedID 27248860

• Time-Resolved X-ray Spectroscopy in the Water Window: Elucidating Transient Valence Charge Distributions in an Aqueous Fe(II) Complex JOURNAL OF PHYSICAL CHEMISTRY LETTERS Van Kuiken, B. E., Cho, H., Hong, K., Khalil, M., Schoenlein, R. W., Kim, T., Huse, N. 2016; 7 (3): 465–70

  Abstract

  Time-resolved nitrogen-1s spectroscopy in the X-ray water window is presented as a novel probe of metal-ligand interactions and transient states in nitrogen-containing organic compounds. New information on iron(II) polypyridyl complexes via nitrogen core-level transitions yields insight into the charge density of the photoinduced high-spin state by comparing experimental results with time-dependent density functional theory. In the transient high-spin state, the 3d electrons of the metal center are more delocalized over the nearest-neighbor nitrogen atoms despite increased bond lengths. Our findings point to a strong coupling of electronic states with charge-transfer character, facilitating the ultrafast intersystem crossing cascade in these systems. The study also highlights the importance of local charge density measures to complement chemical interaction concepts of charge donation and back-bonding with molecular orbital descriptions of states.

  View details for DOI 10.1021/acs.jpclett.5b02509

  View details for Web of Science ID 000369774400017

  View details for PubMedID 26727390

• Electronic and nuclear contributions to time-resolved optical and X-ray absorption spectra of hematite and insights into photoelectrochemical performance Energy & Environmental Science Hayes, D., Hadt, R. G., Emery, J. D., Cordones, A. A., Martinson, A. F., Shelby, M. L., Fransted, K. A., Dahlberg, P. D., Hong, J., Zhang, X., Kong, Q., Schoenlein, R. W., Chen, L. X. 2016; 9 (12): 3754–69

  View details for DOI 10.1039/c6ee02266a

  View details for Web of Science ID 000392915500016

• Tracking reaction dynamics in solution by pump-probe X-ray absorption spectroscopy and X-ray liquidography (solution scattering) CHEMICAL COMMUNICATIONS Kim, J., Kim, K., Oang, K., Lee, J., Hong, K., Cho, H., Huse, N., Schoenlein, R. W., Kim, T., Ihee, H. 2016; 52 (19): 3734–49

  Abstract

  Characterization of transient molecular structures formed during chemical and biological processes is essential for understanding their mechanisms and functions. Over the last decade, time-resolved X-ray liquidography (TRXL) and time-resolved X-ray absorption spectroscopy (TRXAS) have emerged as powerful techniques for molecular and electronic structural analysis of photoinduced reactions in the solution phase. Both techniques make use of a pump-probe scheme that consists of (1) an optical pump pulse to initiate a photoinduced process and (2) an X-ray probe pulse to monitor changes in the molecular structure as a function of time delay between pump and probe pulses. TRXL is sensitive to changes in the global molecular structure and therefore can be used to elucidate structural changes of reacting solute molecules as well as the collective response of solvent molecules. On the other hand, TRXAS can be used to probe changes in both local geometrical and electronic structures of specific X-ray-absorbing atoms due to the element-specific nature of core-level transitions. These techniques are complementary to each other and a combination of the two methods will enhance the capability of accurately obtaining structural changes induced by photoexcitation. Here we review the principles of TRXL and TRXAS and present recent application examples of the two methods for studying chemical and biological processes in solution. Furthermore, we briefly discuss the prospect of using X-ray free electron lasers for the two techniques, which will allow us to keep track of structural dynamics on femtosecond time scales in various solution-phase molecular reactions.

  View details for DOI 10.1039/c5cc08949b

  View details for Web of Science ID 000371477100001

  View details for PubMedID 26785280

• Scattering bottleneck for spin dynamics in metallic helical antiferromagnetic dysprosium PHYSICAL REVIEW B Langner, M. C., Roy, S., Kemper, A. F., Chuang, Y., Mishra, S. K., Versteeg, R. B., Zhu, Y., Hertlein, M. P., Glover, T. E., Dumesnil, K., Schoenlein, R. W. 2015; 92 (18)

  View details for DOI 10.1103/PhysRevB.92.184423

  View details for Web of Science ID 000365506600006

• Selective interlayer ferromagnetic coupling between the Cu spins in YBa2Cu3O7-x grown on top of La0.7Ca0.3MnO3 SCIENTIFIC REPORTS Huang, S. W., Wray, L. A., Jeng, H., Tra, V. T., Lee, J. M., Langner, M. C., Chen, J. M., Roy, S., Chu, Y. H., Schoenlein, R. W., Chuang, Y., Lin, J. 2015; 5

  Abstract

  Studies to date on ferromagnet/d-wave superconductor heterostructures focus mainly on the effects at or near the interfaces while the response of bulk properties to heterostructuring is overlooked. Here we use resonant soft x-ray scattering spectroscopy to reveal a novel c-axis ferromagnetic coupling between the in-plane Cu spins in YBa2Cu3O7-x (YBCO) superconductor when it is grown on top of ferromagnetic La0.7Ca0.3MnO3 (LCMO) manganite layer. This coupling, present in both normal and superconducting states of YBCO, is sensitive to the interfacial termination such that it is only observed in bilayers with MnO2 but not with La0.7Ca0.3O interfacial termination. Such contrasting behaviors, we propose, are due to distinct energetic of CuO chain and CuO2 plane at the La0.7Ca0.3O and MnO2 terminated interfaces respectively, therefore influencing the transfer of spin-polarized electrons from manganite to cuprate differently. Our findings suggest that the superconducting/ferromagnetic bilayers with proper interfacial engineering can be good candidates for searching the theorized Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) state in cuprates and studying the competing quantum orders in highly correlated electron systems.

  View details for DOI 10.1038/srep16690

  View details for Web of Science ID 000364753200001

  View details for PubMedID 26573394

  View details for PubMedCentralID PMC4648077

• Element-Specific Characterization of Transient Electronic Structure of Solvated Fe(II) Complexes with Time-Resolved Soft X-ray Absorption Spectroscopy ACCOUNTS OF CHEMICAL RESEARCH Hong, K., Cho, H., Schoenlein, R. W., Kim, T., Huse, N. 2015; 48 (11): 2957–66

  Abstract

  Polypyridyl transition-metal complexes are an intriguing class of compounds due to the relatively facile chemical designs and variations in ligand-field strengths that allow for spin-state changes and hence electronic configurations in response to external perturbations such as pressure and light. Light-activated spin-conversion complexes have possible applications in a variety of molecular-based devices, and ultrafast excited-state evolution in these complexes is of fundamental interest for understanding of the origins of spin-state conversion in metal complexes. Knowledge of the interplay of structure and valence charge distributions is important to understand which degrees of freedom drive spin-conversion and which respond in a favorable (or unfavorable) manner. To track the response of the constituent components, various types of time-resolved X-ray probe methods have been utilized for a broad range of chemical and biological systems relevant to catalysis, solar energy conversions, and functional molecular devices. In particular, transient soft X-ray spectroscopy of solvated molecules can offer complementary information on the detailed electronic structures and valence charge distributions of photoinduced intermediate species: First-row transition-metal L-edges consist of 2p-3d transitions, which directly probe the unoccupied valence density of states and feature lifetime broadening in the range of 100 meV, making them sensitive spectral probes of metal-ligand interactions. In this Account, we present some of our recent progress in employing picosecond and femtosecond soft X-ray pulses from synchrotron sources to investigate element specific valence charge distributions and spin-state evolutions in Fe(II) polypyridyl complexes via core-level transitions. Our results on transient L-edge spectroscopy of Fe(II) complexes clearly show that the reduction in σ-donation is compensated by significant attenuation of π-backbonding upon spin-crossover. This underscores the important information contained in transient metal L-edge spectroscopy on changes in the 3d orbitals including oxidation states, orbital symmetries, and covalency, which largely define the chemistry of these complexes. In addition, ligand K-edge spectroscopy reveals the "ligand view" of the valence charge density by probing 1s-2p core-level transitions at the K-edge of light elements such as nitrogen, carbon, and oxygen. In the case of Fe(II) spin-conversion complexes, additional details of the metal-ligand interactions can be obtained by this type of X-ray spectroscopy. With new initiatives in and construction of X-ray free-electron laser sources, we expect time-resolved soft X-ray spectroscopy to pave a new way to study electronic and molecular dynamics of functional materials, thereby answering many interesting scientific questions in inorganic chemistry and material science.

  View details for DOI 10.1021/acs.accounts.5b00154

  View details for Web of Science ID 000365150500017

  View details for PubMedID 26488127

• Ultrafast x-ray and optical signatures of phase competition and separation underlying the photoinduced metallic phase in Pr1-xCaxMnO3 PHYSICAL REVIEW B Langner, M. C., Zhou, S., Coslovich, G., Chuang, Y., Zhu, Y., ROBINSON, J. S., Schlotter, W. F., Turner, J. J., Minitti, M. P., Moore, R. G., Lee, W. S., Lu, D. H., Doering, D., Denes, P., Tomioka, Y., Tokura, Y., Kaindl, R. A., Schoenlein, R. W. 2015; 92 (15)

  View details for DOI 10.1103/PhysRevB.92.155148

  View details for Web of Science ID 000363790400002

• Sub-nanosecond time-resolved ambient-pressure X-ray photoelectron spectroscopy setup for pulsed and constant wave X-ray light sources REVIEW OF SCIENTIFIC INSTRUMENTS Shavorskiy, A., Neppl, S., Slaughter, D. S., Cryan, J. P., Siefermann, K. R., Weise, F., Lin, M., Bacellar, C., Ziemkiewicz, M. P., Zegkinoglou, I., Fraund, M. W., Khurmi, C., Hertlein, M. P., Wright, T. W., Huse, N., Schoenlein, R. W., Tyliszczak, T., Coslovich, G., Robinson, J., Kaindl, R. A., Rude, B. S., Oelsner, A., Maehl, S., Bluhm, H., Gessner, O. 2014; 85 (9): 093102

  Abstract

  An apparatus for sub-nanosecond time-resolved ambient-pressure X-ray photoelectron spectroscopy studies with pulsed and constant wave X-ray light sources is presented. A differentially pumped hemispherical electron analyzer is equipped with a delay-line detector that simultaneously records the position and arrival time of every single electron at the exit aperture of the hemisphere with ~0.1 mm spatial resolution and ~150 ps temporal accuracy. The kinetic energies of the photoelectrons are encoded in the hit positions along the dispersive axis of the two-dimensional detector. Pump-probe time-delays are provided by the electron arrival times relative to the pump pulse timing. An average time-resolution of (780 ± 20) ps (FWHM) is demonstrated for a hemisphere pass energy E(p) = 150 eV and an electron kinetic energy range KE = 503-508 eV. The time-resolution of the setup is limited by the electron time-of-flight (TOF) spread related to the electron trajectory distribution within the analyzer hemisphere and within the electrostatic lens system that images the interaction volume onto the hemisphere entrance slit. The TOF spread for electrons with KE = 430 eV varies between ~9 ns at a pass energy of 50 eV and ~1 ns at pass energies between 200 eV and 400 eV. The correlation between the retarding ratio and the TOF spread is evaluated by means of both analytical descriptions of the electron trajectories within the analyzer hemisphere and computer simulations of the entire trajectories including the electrostatic lens system. In agreement with previous studies, we find that the by far dominant contribution to the TOF spread is acquired within the hemisphere. However, both experiment and computer simulations show that the lens system indirectly affects the time resolution of the setup to a significant extent by inducing a strong dependence of the angular spread of electron trajectories entering the hemisphere on the retarding ratio. The scaling of the angular spread with the retarding ratio can be well approximated by applying Liouville's theorem of constant emittance to the electron trajectories inside the lens system. The performance of the setup is demonstrated by characterizing the laser fluence-dependent transient surface photovoltage response of a laser-excited Si(100) sample.

  View details for PubMedID 25273702

• Atomic-Scale Perspective of Ultrafast Charge Transfer at a Dye-Semiconductor Interface JOURNAL OF PHYSICAL CHEMISTRY LETTERS Siefermann, K. R., Pemmaraju, C. D., Neppl, S., Shavorskiy, A., Cordones, A. A., Vura-Weis, J., Slaughter, D. S., Sturm, F. P., Weise, F., Bluhm, H., Strader, M. L., Cho, H., Lin, M., Bacellar, C., Khurmi, C., Guo, J., Coslovich, G., Robinson, J. S., Kaindl, R. A., Schoenlein, R. W., Belkacem, A., Neumark, D. M., Leone, S. R., Nordlund, D., Ogasawara, H., Krupin, O., Turner, J. J., Schlotter, W. F., Holmes, M. R., Messerschmidt, M., Minitti, M. P., Gul, S., Zhang, J. Z., Huse, N., Prendergast, D., Gessner, O. 2014; 5 (15): 2753-2759

  Abstract

  Understanding interfacial charge-transfer processes on the atomic level is crucial to support the rational design of energy-challenge relevant systems such as solar cells, batteries, and photocatalysts. A femtosecond time-resolved core-level photoelectron spectroscopy study is performed that probes the electronic structure of the interface between ruthenium-based N3 dye molecules and ZnO nanocrystals within the first picosecond after photoexcitation and from the unique perspective of the Ru reporter atom at the center of the dye. A transient chemical shift of the Ru 3d inner-shell photolines by (2.3 ± 0.2) eV to higher binding energies is observed 500 fs after photoexcitation of the dye. The experimental results are interpreted with the aid of ab initio calculations using constrained density functional theory. Strong indications for the formation of an interfacial charge-transfer state are presented, providing direct insight into a transient electronic configuration that may limit the efficiency of photoinduced free charge-carrier generation.

  View details for DOI 10.1021/jz501264x

  View details for Web of Science ID 000340222200044

  View details for PubMedID 26277975

• Coupled Skyrmion Sublattices in Cu2OSeO3 PHYSICAL REVIEW LETTERS Langner, M. C., Roy, S., Mishra, S. K., Lee, J. T., Shi, X. W., Hossain, M. A., Chuang, Y., Seki, S., Tokura, Y., Kevan, S. D., Schoenlein, R. W. 2014; 112 (16): 167202

  Abstract

  We report the observation of a Skyrmion lattice in the chiral multiferroic insulator Cu2OSeO3 using Cu L3-edge resonant soft x-ray diffraction. We observe the unexpected existence of two distinct Skyrmion sublattices that arise from inequivalent Cu sites with chemically identical coordination numbers but different magnetically active orbitals. The Skyrmion sublattices are rotated with respect to each other, implying a long wavelength modulation of the lattice. The modulation vector is controlled with an applied magnetic field, associating this moirélike phase with a continuous phase transition. Our findings will open up a new class of science involving manipulation of quantum topological states.

  View details for DOI 10.1103/PhysRevLett.112.167202

  View details for Web of Science ID 000335866200015

  View details for PubMedID 24815665

• Glass-like recovery of antiferromagnetic spin ordering in a photo-excited manganite Pr0.7Ca0.3MnO3 SCIENTIFIC REPORTS Zhou, S. Y., Langner, M. C., Zhu, Y., Chuang, Y., Rini, M., Glover, T. E., Hertlein, M. P., Gonzalez, A., Tahir, N., Tomioka, Y., Tokura, Y., Hussain, Z., Schoenlein, R. W. 2014; 4: 4050

  Abstract

  Electronic orderings of charges, orbitals and spins are observed in many strongly correlated electron materials, and revealing their dynamics is a critical step toward undertsanding the underlying physics of important emergent phenomena. Here we use time-resolved resonant soft x-ray scattering spectroscopy to probe the dynamics of antiferromagnetic spin ordering in the manganite Pr₀.₇Ca₀.₃MnO₃ following ultrafast photo-exitation. Our studies reveal a glass-like recovery of the spin ordering and a crossover in the dimensionality of the restoring interaction from quasi-1D at low pump fluence to 3D at high pump fluence. This behavior arises from the metastable state created by photo-excitation, a state characterized by spin disordered metallic droplets within the larger charge- and spin-ordered insulating domains. Comparison with time-resolved resistivity measurements suggests that the collapse of spin ordering is correlated with the insulator-to-metal transition, but the recovery of the insulating phase does not depend on the re-establishment of the spin ordering.

  View details for DOI 10.1038/srep04050

  View details for Web of Science ID 000331291200001

  View details for PubMedID 24522173

  View details for PubMedCentralID PMC3923209

• Ultrafast charge localization in a stripe-phase nickelate NATURE COMMUNICATIONS Coslovich, G., Huber, B., Lee, W., Chuang, Y., Zhu, Y., Sasagawa, T., Hussain, Z., Bechtel, H. A., Martin, M. C., Shen, Z., Schoenlein, R. W., Kaindl, R. A. 2013; 4

  Abstract

  Self-organized electronically ordered phases are a recurring feature in correlated materials, resulting in, for example, fluctuating charge stripes whose role in high-TC superconductivity is under debate. However, the relevant cause-effect relations between real-space charge correlations and low-energy excitations remain hidden in time-averaged studies. Here we reveal ultrafast charge localization and lattice vibrational coupling as dynamic precursors of stripe formation in the model compound La(1.75)Sr(0.25)NiO4, using ultrafast and equilibrium mid-infrared spectroscopy. The opening of a pseudogap at a crossover temperature T* far above long-range stripe formation establishes the onset of electronic localization, which is accompanied by an enhanced Fano asymmetry of Ni-O stretch vibrations. Ultrafast excitation triggers a sub-picosecond dynamics exposing the synchronous modulation of electron-phonon coupling and charge localization. These results illuminate the role of localization in forming the pseudogap in nickelates, opening a path to understanding this mysterious phase in a broad class of complex oxides.

  View details for DOI 10.1038/ncomms3643

  View details for Web of Science ID 000326472400006

  View details for PubMedCentralID PMC3826635

• Ultra-fast and ultra-intense x-ray sciences: first results from the Linac Coherent Light Source free-electron laser JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS Bostedt, C., Bozek, J. D., Bucksbaum, P. H., Coffee, R. N., Hastings, J. B., Huang, Z., Lee, R. W., Schorb, S., Corlett, J. N., Denes, P., Emma, P., Falcone, R. W., Schoenlein, R. W., Doumy, G., Kanter, E. P., Kraessig, B., Southworth, S., Young, L., Fang, L., Hoener, M., Berrah, N., Roedig, C., DiMauro, L. F. 2013; 46 (16)

  View details for DOI 10.1088/0953-4075/46/16/164003

  View details for Web of Science ID 000323113100004

• Simulating Ru L-3-Edge X-ray Absorption Spectroscopy with Time-Dependent Density Functional Theory: Model Complexes and Electron Localization in Mixed-Valence Metal Dimers JOURNAL OF PHYSICAL CHEMISTRY A Van Kuiken, B. E., Valiev, M., Daifuku, S. L., Bannan, C., Strader, M. L., Cho, H., Huse, N., Schoenlein, R. W., Govind, N., Khalil, M. 2013; 117 (21): 4444–54

  Abstract

  Ruthenium L3-edge X-ray absorption (XA) spectroscopy probes unoccupied 4d orbitals of the metal atom and is increasingly being used to investigate the local electronic structure in ground and excited electronic states of Ru complexes. The simultaneous development of computational tools for simulating Ru L3-edge spectra is crucial for interpreting the spectral features at a molecular level. This study demonstrates that time-dependent density functional theory (TDDFT) is a viable and predictive tool for simulating ruthenium L3-edge XA spectroscopy. We systematically investigate the effects of exchange correlation functional and implicit and explicit solvent interactions on a series of Ru(II) and Ru(III) complexes in their ground and electronic excited states. The TDDFT simulations reproduce all of the experimentally observed features in Ru L3-edge XA spectra within the experimental resolution (0.4 eV). Our simulations identify ligand-specific charge transfer features in complicated Ru L3-edge spectra of [Ru(CN)6](4-) and Ru(II) polypyridyl complexes illustrating the advantage of using TDDFT in complex systems. We conclude that the B3LYP functional most accurately predicts the transition energies of charge transfer features in these systems. We use our TDDFT approach to simulate experimental Ru L3-edge XA spectra of transition metal mixed-valence dimers of the form [(NC)5M(II)-CN-Ru(III)(NH3)5](-) (where M = Fe or Ru) dissolved in water. Our study determines the spectral signatures of electron delocalization in Ru L3-edge XA spectra. We find that the inclusion of explicit solvent molecules is necessary for reproducing the spectral features and the experimentally determined valencies in these mixed-valence complexes. This study validates the use of TDDFT for simulating Ru 2p excitations using popular quantum chemistry codes and providing a powerful interpretive tool for equilibrium and ultrafast Ru L3-edge XA spectroscopy.

  View details for DOI 10.1021/jp401020j

  View details for Web of Science ID 000319896900013

  View details for PubMedID 23635307

• Real-Time Manifestation of Strongly Coupled Spin and Charge Order Parameters in Stripe-Ordered La1.75Sr0.25NiO4 Nickelate Crystals Using Time-Resolved Resonant X-Ray Diffraction PHYSICAL REVIEW LETTERS Chuang, Y. D., Lee, W. S., Kung, Y. F., Sorini, A. P., Moritz, B., Moore, R. G., Patthey, L., Trigo, M., Lu, D. H., Kirchmann, P. S., Yi, M., Krupin, O., Langner, M., Zhu, Y., Zhou, S. Y., Reis, D. A., Huse, N., ROBINSON, J. S., Kaindl, R. A., Schoenlein, R. W., Johnson, S. L., Foerst, M., Doering, D., Denes, P., Schlotter, W. F., Turner, J. J., Sasagawa, T., Hussain, Z., Shen, Z. X., Devereaux, T. P. 2013; 110 (12)

  Abstract

  We investigate the order parameter dynamics of the stripe-ordered nickelate, La_{1.75}Sr_{0.25}NiO_{4}, using time-resolved resonant x-ray diffraction. In spite of distinct spin and charge energy scales, the two order parameters' amplitude dynamics are found to be linked together due to strong coupling. Additionally, the vector nature of the spin sector introduces a longer reorientation time scale which is absent in the charge sector. These findings demonstrate that the correlation linking the symmetry-broken states does not unbind during the nonequilibrium process, and the time scales are not necessarily associated with the characteristic energy scales of individual degrees of freedom.

  View details for DOI 10.1103/PhysRevLett.110.127404

  View details for Web of Science ID 000316411100019

• Ultrast Mid-infrared Spectroscopy of the Charge- and Spin-Ordered Nickelate La1.75Sr0.25NiO4 18th International Conference on Ultrafast Phenomena Coslovich, G., Huber, B., Lee, W., Chuang, Y., Zhu, Y., Sasagawa, T., Hussain, Z., Bechtel, H. A., Martin, M. C., Schoenlein, R. W., Shen, Z., Kaindl, R. A. E D P SCIENCES. 2013

  View details for DOI 10.1051/epjconf/20134103016

  View details for Web of Science ID 000320558600073

• Elucidating Charge Delocalization in the High-Spin State of aqueous Fe-II Spin-Crossover Compounds via Time-Resolved Spectroscopy in the X-ray Water Window Huse, N., Van Kuiken, B. E., Cho, H., Strader, M. L., Kim, T., Khalil, M., Schoenlein, R. W., Chergui, M., Taylor, A., Cundiff, S., DeVivieRiedle, R., Yamagouchi, K. E D P SCIENCES. 2013

  View details for DOI 10.1051/epjconf/20134105037

  View details for Web of Science ID 000320558600157

• Time-Resolved X-Ray Photoelectron Spectroscopy Techniques For Real-Time Studies Of Interfacial Charge Transfer Dynamics 22nd International Conference on the Application of Accelerators in Research and Industry (CAARI) Shavorskiy, A., Cordones, A., Vura-Weis, J., Siefermann, K., Slaughter, D., Sturm, F., Weise, F., Bluhm, H., Strader, M., Cho, H., Lin, M., Bacellar, C., Khurmi, C., Hertlein, M., Guo, J., Tyliszczak, T., Prendergast, D., Coslovich, G., Robinson, J., Kaindl, R. A., Schoenlein, R. W., Belkacem, A., Weber, T., Neumark, D. M., Leone, S. R., Nordlund, D., Ogasawara, H., Nilsson, A. R., Krupin, O., Turner, J. J., Schlotter, W. F., Holmes, M. R., Heimann, P. A., Messerschmidt, M., Minitti, M. P., Beye, M., Gul, S., Zhang, J. Z., Huse, N., Gessner, O. AMER INST PHYSICS. 2013: 475–479

  View details for DOI 10.1063/1.4802374

  View details for Web of Science ID 000319997900095

• Tracking Charge Localization via Transient Electron-Phonon Coupling in a Stripe-ordered Nickelate Coslovich, G., Huber, B., Lee, W., Chuang, Y., Zhu, Y., Sasagawa, T., Hussain, Z., Bechtel, H. A., Martin, M. C., Shen, Z., Schoenlein, R. W., Kaindl, R. A., IEEE IEEE. 2013

  View details for Web of Science ID 000355262505316

• Ultrafast Mid-infrared Spectroscopy of the Charge- and Spin-ordered Nickelates Conference on Ultrafast Phenomena and Nanophotonics XVII Coslovich, G., Huber, B., Lee, W., Chuang, Y., Zhu, Y., Sasagawa, T., Hussain, Z., Bechtel, H. A., Martin, M. C., Schoenlein, R. W., Shen, Z., Kaindl, R. A. SPIE-INT SOC OPTICAL ENGINEERING. 2013

  View details for DOI 10.1117/12.2005366

  View details for Web of Science ID 000322829300006

• Observation of Coherent Helimagnons and Gilbert Damping in an Itinerant Magnet PHYSICAL REVIEW LETTERS Koralek, J. D., Meier, D., Hinton, J. P., Bauer, A., Parameswaran, S. A., Vishwanath, A., Ramesh, R., Schoenlein, R. W., Pfleiderer, C., Orenstein, J. 2012; 109 (24): 247204

  Abstract

  We study the magnetic excitations of itinerant helimagnets by applying time-resolved optical spectroscopy to Fe(0.8)Co(0.2)Si. Optically excited oscillations of the magnetization in the helical state are found to disperse to lower frequency as the applied magnetic field is increased; the fingerprint of collective modes unique to helimagnets, known as helimagnons. The use of time-resolved spectroscopy allows us to address the fundamental magnetic relaxation processes by directly measuring the Gilbert damping, revealing the versatility of spin dynamics in chiral magnets.

  View details for DOI 10.1103/PhysRevLett.109.247204

  View details for Web of Science ID 000312299500010

  View details for PubMedID 23368372

• Probing the Electronic Structure of a Photoexcited Solar Cell Dye with Transient X-ray Absorption Spectroscopy JOURNAL OF PHYSICAL CHEMISTRY LETTERS Van Kuiken, B. E., Huse, N., Cho, H., Strader, M. L., Lynch, M. S., Schoenlein, R. W., Khalil, M. 2012; 3 (12): 1695–1700

  Abstract

  This study uses transient X-ray absorption (XA) spectroscopy and time-dependent density functional theory (TD-DFT) to directly visualize the charge density around the metal atom and the surrounding ligands following an ultrafast metal-to-ligand charge-transfer (MLCT) process in the widely used Ru(II) solar cell dye, Ru(dcbpy)2(NCS)2 (termed N3). We measure the Ru L-edge XA spectra of the singlet ground ((1)A1) and the transient triplet ((3)MLCT) excited state of N3(4-) and perform TD-DFT calculations of 2p core-level excitations, which identify a unique spectral signature of the electron density on the NCS ligands. We find that the Ru 2p, Ru eg, and NCS π* orbitals are stabilized by 2.0, 1.0, and 0.6 eV, respectively, in the transient (3)MLCT state of the dye. These results highlight the role of the NCS ligands in governing the oxidation state of the Ru center.

  View details for DOI 10.1021/jz300671e

  View details for Web of Science ID 000305662200021

  View details for PubMedID 26285730

• Phase fluctuations and the absence of topological defects in a photo-excited charge-ordered nickelate NATURE COMMUNICATIONS Lee, W. S., Chuang, Y. D., Moore, R. G., Zhu, Y., Patthey, L., Trigo, M., Lu, D. H., Kirchmann, P. S., Krupin, O., Yi, M., Langner, M., Huse, N., ROBINSON, J. S., Chen, Y., Zhou, S. Y., Coslovich, G., Huber, B., Reis, D. A., Kaindl, R. A., Schoenlein, R. W., Doering, D., Denes, P., Schlotter, W. F., Turner, J. J., Johnson, S. L., Foerst, M., Sasagawa, T., Kung, Y. F., Sorini, A. P., Kemper, A. F., Moritz, B., Devereaux, T. P., Lee, D., Shen, Z. X., Hussain, Z. 2012; 3

  Abstract

  The dynamics of an order parameter's amplitude and phase determines the collective behaviour of novel states emerging in complex materials. Time- and momentum-resolved pump-probe spectroscopy, by virtue of measuring material properties at atomic and electronic time scales out of equilibrium, can decouple entangled degrees of freedom by visualizing their corresponding dynamics in the time domain. Here we combine time-resolved femotosecond optical and resonant X-ray diffraction measurements on charge ordered La(1.75)Sr(0.25)NiO(4) to reveal unforeseen photoinduced phase fluctuations of the charge order parameter. Such fluctuations preserve long-range order without creating topological defects, distinct from thermal phase fluctuations near the critical temperature in equilibrium. Importantly, relaxation of the phase fluctuations is found to be an order of magnitude slower than that of the order parameter's amplitude fluctuations, and thus limits charge order recovery. This new aspect of phase fluctuations provides a more holistic view of the phase's importance in ordering phenomena of quantum matter.

  View details for DOI 10.1038/ncomms1837

  View details for Web of Science ID 000304611400033

  View details for PubMedID 22588300

• Ligand-field symmetry effects in Fe(II) polypyridyl compounds probed by transient X-ray absorption spectroscopy FARADAY DISCUSSIONS Cho, H., Strader, M. L., Hong, K., Jamula, L., Gullikson, E. M., Kim, T., de Groot, F. F., McCusker, J. K., Schoenlein, R. W., Huse, N. 2012; 157: 463–74

  Abstract

  Ultrafast excited-state evolution in polypyridyl Fe(II) complexes is of fundamental interest for understanding the origins of the sub-ps spin-state changes that occur upon photoexcitation of this class of compounds as well as for the potential impact such ultrafast dynamics have on incorporation of these compounds in solar energy conversion schemes or switchable optical storage technologies. We have demonstrated that ground-state and, more importantly, ultrafast time-resolved X-ray absorption methods can offer unique insights into the interplay between electronic and geometric structure that underpins the photo-induced dynamics of this class of compounds. The present contribution examines in greater detail how the symmetry of the ligand field surrounding the metal ion can be probed using these X-ray techniques. In particular, we show that steady-state K-edge spectroscopy of the nearest-neighbour nitrogen atoms reveals the characteristic chemical environment of the respective ligands and suggests an interesting target for future charge-transfer femtosecond and attosecond spectroscopy in the X-ray water window.

  View details for DOI 10.1039/c2fd20040f

  View details for Web of Science ID 000309137600026

  View details for PubMedID 23230783

• Ultrafast Dynamics of the Mid-infrared Pseudogap in Stripe-phase La1.75Sr0.25NiO4 Coslovich, G., Huber, B., Lee, W., Chuang, Y., Zhu, Y., Sasagawa, T., Hussain, Z., Bechtel, H. A., Martin, M. C., Schoenlein, R. W., Shen, Z., Kaindl, R. A., IEEE IEEE. 2012

  View details for Web of Science ID 000310362403090

• Advances in Ultrafast Control and Probing of Correlated-Electron Materials IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS Wall, S., Rini, M., Dhesi, S. S., Schoenlein, R. W., Cavalleri, A. 2012; 18 (1): 81–91

  View details for DOI 10.1109/JSTQE.2011.2105465

  View details for Web of Science ID 000299933700010

• Ferromagnetic Enhancement of CE-Type Spin Ordering in (Pr, Ca)MnO3 PHYSICAL REVIEW LETTERS Zhou, S. Y., Zhu, Y., Langner, M. C., Chuang, Y., Yu, P., Yang, W. L., Gonzalez, A., Tahir, N., Rini, M., Chu, Y., Ramesh, R., Lee, D., Tomioka, Y., Tokura, Y., Hussain, Z., Schoenlein, R. W. 2011; 106 (18): 186404

  Abstract

  We present resonant soft x-ray scattering results from small bandwidth manganites (Pr,Ca)MnO(3), which show that the CE-type spin ordering (SO) at the phase boundary is stabilized only below the canted antiferromagnetic transition temperature and enhanced by ferromagnetism in the macroscopically insulating state (FM-I). Our results reveal the fragility of the CE-type ordering that underpins the colossal magnetoresistance effect in this system, as well as an unexpected cooperative interplay between FM-I and CE-type SO which is in contrast to the competitive interplay between the ferromagnetic metallic state and CE-type ordering.

  View details for DOI 10.1103/PhysRevLett.106.186404

  View details for Web of Science ID 000290229100003

  View details for PubMedID 21635110

• Femtosecond Soft X-ray Spectroscopy of Solvated Transition-Metal Complexes: Deciphering the Interplay of Electronic and Structural Dynamics JOURNAL OF PHYSICAL CHEMISTRY LETTERS Huse, N., Cho, H., Hong, K., Jamula, L., de Groot, F. F., Kim, T., McCusker, J. K., Schoenlein, R. W. 2011; 2 (8): 880–84

  Abstract

  We present the first implementation of femtosecond soft X-ray spectroscopy as an ultrafast direct probe of the excited-state valence orbitals in solution-phase molecules. This method is applied to photoinduced spin crossover of [Fe(tren(py)3)](2+), where the ultrafast spin-state conversion of the metal ion, initiated by metal-to-ligand charge-transfer excitation, is directly measured using the intrinsic spin-state selectivity of the soft X-ray L-edge transitions. Our results provide important experimental data concerning the mechanism of ultrafast spin-state conversion and subsequent electronic and structural dynamics, highlighting the potential of this technique to study ultrafast phenomena in the solution phase.

  View details for DOI 10.1021/jz200168m

  View details for Web of Science ID 000289824800007

  View details for PubMedID 26295622

• Photo-Induced Spin-State Conversion in Solvated Transition Metal Complexes Probed via Time-Resolved Soft X-ray Spectroscopy JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Huse, N., Kim, T., Jamula, L., McCusker, J. K., de Groot, F. F., Schoenlein, R. W. 2010; 132 (19): 6809–16

  Abstract

  Solution-phase photoinduced low-spin to high-spin conversion in the Fe(II) polypyridyl complex [Fe(tren(py)(3))](2+) (where tren(py)(3) is tris(2-pyridylmethyliminoethyl)amine) has been studied via picosecond soft X-ray spectroscopy. Following (1)A(1) --> (1)MLCT (metal-to-ligand charge transfer) excitation at 560 nm, changes in the iron L(2)- and L(3)-edges were observed concomitant with formation of the transient high-spin (5)T(2) state. Charge-transfer multiplet calculations coupled with data acquired on low-spin and high-spin model complexes revealed a reduction in ligand field splitting of approximately 1 eV in the high-spin state relative to the singlet ground state. A significant reduction in orbital overlap between the central Fe-3d and the ligand N-2p orbitals was directly observed, consistent with the expected ca. 0.2 A increase in Fe-N bond length upon formation of the high-spin state. The overall occupancy of the Fe-3d orbitals remains constant upon spin crossover, suggesting that the reduction in sigma-donation is compensated by significant attenuation of pi-back-bonding in the metal-ligand interactions. These results demonstrate the feasibility and unique potential of time-resolved soft X-ray absorption spectroscopy to study ultrafast reactions in the liquid phase by directly probing the valence orbitals of first-row metals as well as lighter elements during the course of photochemical transformations.

  View details for DOI 10.1021/ja101381a

  View details for Web of Science ID 000277721500041

  View details for PubMedID 20426414

• Ultrafast conversions between hydrogen bonded structures in liquid water observed by femtosecond x-ray spectroscopy JOURNAL OF CHEMICAL PHYSICS Wen, H., Huse, N., Schoenlein, R. W., Lindenberg, A. M. 2009; 131 (23)

  Abstract

  We present the first femtosecond soft x-ray spectroscopy in liquids, enabling the observation of changes in hydrogen bond structures in water via core-hole excitation. The oxygen K-edge of vibrationally excited water is probed with femtosecond soft x-ray pulses, exploiting the relation between different water structures and distinct x-ray spectral features. After excitation of the intramolecular OH stretching vibration, characteristic x-ray absorption changes monitor the conversion of strongly hydrogen-bonded water structures to more disordered structures with weaker hydrogen-bonding described by a single subpicosecond time constant. The latter describes the thermalization time of vibrational excitations and defines the characteristic maximum rate with which nonequilibrium populations of more strongly hydrogen-bonded water structures convert to less-bonded ones. On short time scales, the relaxation of vibrational excitations leads to a transient high-pressure state and a transient absorption spectrum different from that of statically heated water.

  View details for DOI 10.1063/1.3273204

  View details for Web of Science ID 000273036300029

  View details for PubMedID 20025333

• Transient electronic structure of the photoinduced phase of Pr0.7Ca0.3MnO3 probed with soft x-ray pulses PHYSICAL REVIEW B Rini, M., Zhu, Y., Wall, S., Tobey, R. I., Ehrke, H., Garl, T., Freeland, J. W., Tomioka, Y., Tokura, Y., Cavalleri, A., Schoenlein, R. W. 2009; 80 (15)

  View details for DOI 10.1103/PhysRevB.80.155113

  View details for Web of Science ID 000271352000046

• Probing the hydrogen-bond network of water via time-resolved soft X-ray spectroscopy PHYSICAL CHEMISTRY CHEMICAL PHYSICS Huse, N., Wen, H., Nordlund, D., Szilagyi, E., Daranciang, D., Miller, T. A., Nilsson, A., Schoenlein, R. W., Lindenberg, A. M. 2009; 11 (20): 3951-3957

  Abstract

  We report time-resolved studies of hydrogen bonding in liquid H(2)O, in response to direct excitation of the O-H stretch mode at 3 mum, probed via soft X-ray absorption spectroscopy at the oxygen K-edge. This approach employs a newly developed nanofluidic cell for transient soft X-ray spectroscopy in the liquid phase. Distinct changes in the near-edge spectral region (XANES) are observed, and are indicative of a transient temperature rise of 10 K following transient laser excitation and rapid thermalization of vibrational energy. The rapid heating occurs at constant volume and the associated increase in internal pressure, estimated to be 8 MPa, is manifested by distinct spectral changes that differ from those induced by temperature alone. We conclude that the near-edge spectral shape of the oxygen K-edge is a sensitive probe of internal pressure, opening new possibilities for testing the validity of water models and providing new insight into the nature of hydrogen bonding in water.

  View details for DOI 10.1039/b822210j

  View details for Web of Science ID 000266065400018

  View details for PubMedID 19440624

• Time-resolved Studies of Phase Transition Dynamics in Strongly Correlated Manganites Rini, M., Tobey, R., Dean, N., Wall, S., Ehrke, H., Zhu, Y., Tomioka, Y., Tokura, Y., Schoenlein, R. W., Cavalleri, A., Tanaka, K., Ogawa, T., Hashimoto, H., Koshihara, S. IOP PUBLISHING LTD. 2009

  View details for DOI 10.1088/1742-6596/148/1/012013

  View details for Web of Science ID 000269997600013

• Probing Reaction Dynamics of Transition-Metal Complexes in Solution via Time-Resolved X-ray Spectroscopy Huse, N., Khalil, M., Kim, T., Smeigh, A. L., Jamula, L., McCusker, J. K., Schoenlein, R. W., Tanaka, K., Ogawa, T., Hashimoto, H., Koshihara, S. IOP PUBLISHING LTD. 2009

  View details for DOI 10.1088/1742-6596/148/1/012043

  View details for Web of Science ID 000269997600043

• Optical switching in VO2 films by below-gap excitation APPLIED PHYSICS LETTERS Rini, M., Hao, Z., Schoenlein, R. W., Giannetti, C., Parmigiani, F., Fourmaux, S., Kieffer, J. C., Fujimori, A., Onoda, M., Wall, S., Cavalleri, A. 2008; 92 (18)

  View details for DOI 10.1063/1.2921784

  View details for Web of Science ID 000256485700019

• Ultrafast Phase-Transition Induced by Selective Vibrational Excitation in a Magnetoresistive Manganite Rini, M., Tobey, R., Wall, S., Dean, N., Itatani, J., Tomioka, Y., Tokura, Y., Schoenlein, R. W., Cavalleri, A., IEEE IEEE. 2008: 3321-+

  View details for Web of Science ID 000260498401654

• Control of the electronic phase of a manganite by mode-selective vibrational excitation NATURE Rini, M., Tobey, R., Dean, N., Itatani, J., Tomioka, Y., Tokura, Y., Schoenlein, R. W., Cavalleri, A. 2007; 449 (7158): 72-74

  Abstract

  Controlling a phase of matter by coherently manipulating specific vibrational modes has long been an attractive (yet elusive) goal for ultrafast science. Solids with strongly correlated electrons, in which even subtle crystallographic distortions can result in colossal changes of the electronic and magnetic properties, could be directed between competing phases by such selective vibrational excitation. In this way, the dynamics of the electronic ground state of the system become accessible, and new insight into the underlying physics might be gained. Here we report the ultrafast switching of the electronic phase of a magnetoresistive manganite via direct excitation of a phonon mode at 71 meV (17 THz). A prompt, five-order-of-magnitude drop in resistivity is observed, associated with a non-equilibrium transition from the stable insulating phase to a metastable metallic phase. In contrast with light-induced and current-driven phase transitions, the vibrationally driven bandgap collapse observed here is not related to hot-carrier injection and is uniquely attributed to a large-amplitude Mn-O distortion. This corresponds to a perturbation of the perovskite-structure tolerance factor, which in turn controls the electronic bandwidth via inter-site orbital overlap. Phase control by coherent manipulation of selected metal-oxygen phonons should find extensive application in other complex solids--notably in copper oxide superconductors, in which the role of Cu-O vibrations on the electronic properties is currently controversial.

  View details for DOI 10.1038/nature06119

  View details for Web of Science ID 000249233500037

  View details for PubMedID 17805291

• Coherent orbital waves in the photo-induced insulator-metal dynamics of a magnetoresistive manganite NATURE MATERIALS Polli, D., Rini, M., Wall, S., Schoenlein, R. W., Tomioka, Y., Tokura, Y., Cerullo, G., Cavalleri, A. 2007; 6 (9): 643-647

  Abstract

  Photo-excitation can drive strongly correlated electron insulators into competing conducting phases, resulting in giant and ultrafast changes of their electronic and magnetic properties. The underlying non-equilibrium dynamics involve many degrees of freedom at once, whereby sufficiently short optical pulses can trigger the corresponding collective modes of the solid along temporally coherent pathways. The characteristic frequencies of these modes range between the few GHz of acoustic vibrations to the tens or even hundreds of THz for purely electronic excitations. Virtually all experiments so far have used 100 fs or longer pulses, detecting only comparatively slow lattice dynamics. Here, we use sub-10-fs optical pulses to study the photo-induced insulator-metal transition in the magnetoresistive manganite Pr(0.7)Ca(0.3)MnO(3). At room temperature, we find that the time-dependent pathway towards the metallic phase is accompanied by coherent 31 THz oscillations of the optical reflectivity, significantly faster than all lattice vibrations. These high-frequency oscillations are suggestive of coherent orbital waves, crystal-field excitations triggered here by impulsive stimulated Raman scattering. Orbital waves are likely to be initially localized to the small polarons of this room-temperature manganite, coupling to other degrees of freedom at longer times, as photo-domains coalesce into a metallic phase.

  View details for DOI 10.1038/nmat1979

  View details for Web of Science ID 000249236200015

  View details for PubMedID 17694062

• Successful completion of the femtosecond slicing upgrade at the ALS Steier, C., Heimann, P., Marks, S., Robin, D., Schoenlein, R., Wan, W., Wittmer, W., IEEE IEEE. 2007: 3393-3395

  View details for Web of Science ID 000255096304067

• A high-average power femtosecond laser for synchrotron light source applications Wilcox, R. B., Schoenlein, R. W., Hoffman, H. J., Shori, R. K., Hodgson, N. SPIE-INT SOC OPTICAL ENGINEERING. 2007

  View details for DOI 10.1117/12.708685

  View details for Web of Science ID 000246023600027

• Laser seeding of the storage-ring microbunching instability for high-power coherent terahertz radiation PHYSICAL REVIEW LETTERS Byrd, J. M., Hao, Z., Martin, M. C., Robin, D. S., Sannibale, F., Schoenlein, R. W., Zholents, A. A., Zolotorev, M. S. 2006; 97 (7): 074802

  Abstract

  We report the first observation of laser seeding of the storage-ring microbunching instability. Above a threshold bunch current, the interaction of the beam and its radiation results in a coherent instability, observed as a series of stochastic bursts of coherent synchrotron radiation (CSR) at terahertz frequencies initiated by fluctuations in the beam density. We have observed that this effect can be seeded by imprinting an initial density modulation on the beam by means of laser "slicing." In such a situation, most of the bursts of CSR become synchronous with the pulses of the modulating laser and their average intensity scales exponentially with the current per bunch. We present detailed experimental observations of the seeding effect and a model of the phenomenon. This seeding mechanism also creates potential applications as a high-power source of CSR at terahertz frequencies.

  View details for DOI 10.1103/PhysRevLett.97.074802

  View details for Web of Science ID 000239842100024

  View details for PubMedID 17026236

• Tracking the motion of charges in a terahertz light field by femtosecond X-ray diffraction NATURE Cavalleri, A., Wall, S., Simpson, C., Statz, E., Ward, D. W., Nelson, K. A., Rini, M., Schoenlein, R. W. 2006; 442 (7103): 664-666

  Abstract

  In condensed matter, light propagation near resonances is described in terms of polaritons, electro-mechanical excitations in which the time-dependent electric field is coupled to the oscillation of charged masses. This description underpins our understanding of the macroscopic optical properties of solids, liquids and plasmas, as well as of their dispersion with frequency. In ferroelectric materials, terahertz radiation propagates by driving infrared-active lattice vibrations, resulting in phonon-polariton waves. Electro-optic sampling with femtosecond optical pulses can measure the time-dependent electrical polarization, providing a phase-sensitive analogue to optical Raman scattering. Here we use femtosecond time-resolved X-ray diffraction, a phase-sensitive analogue to inelastic X-ray scattering, to measure the corresponding displacements of ions in ferroelectric lithium tantalate, LiTaO(3). Amplitude and phase of all degrees of freedom in a light field are thus directly measured in the time domain. Notably, extension of other X-ray techniques to the femtosecond timescale (for example, magnetic or anomalous scattering) would allow for studies in complex systems, where electric fields couple to multiple degrees of freedom.

  View details for DOI 10.1038/nature05041

  View details for Web of Science ID 000239630200040

  View details for PubMedID 16900195

• Picosecond X-ray absorption spectroscopy of a photoinduced iron(II) spin crossover reaction in solution JOURNAL OF PHYSICAL CHEMISTRY A Khalil, M., Marcus, M. A., Smeigh, A. L., McCusker, J. K., Chong, H. H., Schoenlein, R. W. 2006; 110 (1): 38-44

  Abstract

  In this study, we perform steady-state and time-resolved X-ray absorption spectroscopy (XAS) on the iron K-edge of [Fe(tren(py)3)](PF6)2 dissolved in acetonitrile solution. Static XAS measurements on the low-spin parent compound and its high-spin analogue, [Fe(tren(6-Me-py)3)](PF6)2, reveal distinct spectroscopic signatures for the two spin states in the X-ray absorption near-edge structure (XANES) and in the X-ray absorption fine structure (EXAFS). For the time-resolved studies, 100 fs, 400 nm pump pulses initiate a charge-transfer transition in the low-spin complex. The subsequent electronic and geometric changes associated with the formation of the high-spin excited state are probed with 70 ps, 7.1 keV, tunable X-ray pulses derived from the Advanced Light Source (ALS). Modeling of the transient XAS data reveals that the average iron-nitrogen (Fe-N) bond is lengthened by 0.21+/-0.03 A in the high-spin excited state relative to the ground state within 70 ps. This structural modification causes a change in the metal-ligand interactions as reflected by the altered density of states of the unoccupied metal orbitals. Our results constitute the first direct measurements of the dynamic atomic and electronic structural rearrangements occurring during a photoinduced FeII spin crossover reaction in solution via picosecond X-ray absorption spectroscopy.

  View details for DOI 10.1021/jp055002q

  View details for Web of Science ID 000234520300007

  View details for PubMedID 16392837

• Ultra-broadband femtosecond measurements of the photo-induced phase transition in VO2: From the mid-IR to the hard x-rays JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Cavalleri, A., Rini, M., Schoenlein, R. W. 2006; 75 (1)

  View details for DOI 10.1143/JPSJ.75.011004

  View details for Web of Science ID 000236105300005

• Band-selective measurements of electron dynamics in VO2 using femtosecond near-edge x-ray absorption PHYSICAL REVIEW LETTERS Cavalleri, A., Rini, M., Chong, H. H., Fourmaux, S., Glover, T. E., Heimann, P. A., Kieffer, J. C., Schoenlein, R. W. 2005; 95 (6): 067405

  Abstract

  We report on the first demonstration of femtosecond x-ray absorption spectroscopy, made uniquely possible by the use of broadly tunable bending-magnet radiation from "laser-sliced" electron bunches within a synchrotron storage ring. We measure the femtosecond electronic rearrangements that occur during the photoinduced insulator-metal phase transition in VO2. Symmetry- and element-specific x-ray absorption from V2p and O1s core levels (near 500 eV) separately measures the filling dynamics of differently hybridized V3d-O2p electronic bands near the Fermi level.

  View details for DOI 10.1103/PhysRevLett.95.067405

  View details for Web of Science ID 000231017700066

  View details for PubMedID 16090991

• Photoinduced phase transition in VO2 nanocrystals: ultrafast control of surface-plasmon resonance OPTICS LETTERS Rini, M., Cavalleri, A., Schoenlein, R. W., Lopez, R., Feldman, L. C., Haglund, R. F., Boatner, L. A., Haynes, T. E. 2005; 30 (5): 558-560

  Abstract

  We study the ultrafast insulator-to-metal transition in nanoparticles of VO2, obtained by ion implantation and self-assembly in silica. The nonmagnetic, strongly correlated compound VO2 undergoes a reversible phase transition, which can be photoinduced on an ultrafast time scale. In the nanoparticles, prompt formation of the metallic state results in the appearance of surface-plasmon resonance. We achieve large, ultrafast enhancement of optical absorption in the near-infrared spectral region that encompasses the wavelength range for optical-fiber communications. One can further tailor the response of the nanoparticles by controlling their shape.

  View details for DOI 10.1364/OL.30.000558

  View details for Web of Science ID 000227371800036

  View details for PubMedID 15789735

• Tailored terahertz pulses from a laser-modulated electron beam Martin, M. C., Byrd, J., Hao, Z., Robin, D., Sannibale, F., Schoenlein, R. W., Zholents, A., Zolotorev, M., IEEE IEEE. 2005: 489-490

  View details for Web of Science ID 000237170000247

• Evidence for a structurally-driven insulator-to-metal transition in VO2: A view from the ultrafast timescale PHYSICAL REVIEW B Cavalleri, A., Dekorsy, T., Chong, H. H., Kieffer, J. C., Schoenlein, R. W. 2004; 70 (16)

  View details for DOI 10.1103/PhysRevB.70.161102

  View details for Web of Science ID 000224856000002

• Picosecond soft x-ray absorption measurement of the photoinduced insulator-to-metal transition in VO2 PHYSICAL REVIEW B Cavalleri, A., Chong, H. H., Fourmaux, S., Glover, T. E., Heimann, P. A., Kieffer, J. C., Mun, B. S., Padmore, H. A., Schoenlein, R. W. 2004; 69 (15)

  View details for DOI 10.1103/PhysRevB.69.153106

  View details for Web of Science ID 000221426800006

• A setup for ultrafast time-resolved x-ray absorption spectroscopy REVIEW OF SCIENTIFIC INSTRUMENTS Saes, M., Bressler, C., van Mourik, F., Gawelda, W., Kaiser, M., Chergui, M., Bressler, C., Grolimund, D., Abela, R., Glover, T. E., Heimann, P. A., Schoenlein, R. W., Johnson, S. L., Lindenberg, A. M., Falcone, R. W. 2004; 75 (1): 24-30

  View details for DOI 10.1063/1.1633003

  View details for Web of Science ID 000187536500003

• Femtosecond X-rays and structural dynamics in condensed matter ULTRAFAST DYNAMICAL PROCESSES IN SEMICONDUCTORS Cavalleri, A., Schoenlein, R. W. 2004; 92: 309-337

  View details for Web of Science ID 000189448300007

• LUX - A recirculating Linac-based ultrafast x-ray source Corlett, J. N., Barletta, W. A., DeSantis, S., Doolittle, L., Fawley, W. M., Green, M. A., Heimann, P., Leone, Lidia, S., Li, D., Parmigiani, F., Ratti, A., Robinson, K., Schoenlein, R., Staples, J., Wan, W., Wells, R., Wilcox, R., Wolski, A., Zholents, A., Warwick, T., Arthur, J., Padmore, H. A., Stohr, J. AMER INST PHYSICS. 2004: 121-124

  View details for Web of Science ID 000222089000029

• ALS Beamline 6.0 for ultrafast X-ray absorption spectroscopy Heimann, P. A., Padmore, H. A., Schoenlein, R. W., Warwick, T., Arthur, J., Padmore, H. A., Stohr, J. AMER INST PHYSICS. 2004: 1407-1410

  View details for Web of Science ID 000222089000345

• Generation of femtosecond synchrotron pulses: Performance and characterization Schoenlein, R. W., Cavalleri, A., Chong, H. H., Glover, T. E., Heimann, P. A., Zholents, A. A., Zolotorev, M. S., Warwick, T., Arthur, J., Padmore, H. A., Stohr, J. AMER INST PHYSICS. 2004: 1403-1406

  View details for Web of Science ID 000222089000344

• LUX: A design study for a linac-/laser-based ultrafast x-ray source Corlett, J. N., Barletta, W. A., DeSantis, S., Doolittle, L., Fawley, W. M., Heimann, P., Leone, S., Lidia, S., Li, D., Penn, G., Ratti, A., Reinsch, M., Schoenlein, R., Staples, J., Stover, G., Virostek, S., Wan, W., Wells, R., Wilcox, R., Wolski, A., Wurtele, J., Zholents, A., Biedron, S. G., Eberhardt, W., Ishikawa, T., Tatchyn, R. O. SPIE-INT SOC OPTICAL ENGINEERING. 2004: 1-12

  View details for DOI 10.1117/12.555946

  View details for Web of Science ID 000225599300001

• Metal-insulator transitions in an expanding metallic fluid: Particle formation kinetics PHYSICAL REVIEW LETTERS Glover, T. E., Ackerman, G. D., Belkacem, A., Heimann, P. A., Hussain, Z., Lee, R. W., Padmore, H. A., Ray, C., Schoenlein, R. W., Steele, W. F., Young, D. A. 2003; 90 (23): 236102

  Abstract

  Core-level photoemission spectroscopy provides a local probe of expansion dynamics and associated transient chemical properties as a highly pressurized, metallic fluid expands into vacuum following impulsive heating of a semiconductor by an intense, ultrashort laser pulse. Transient photoemission peak shifts reveal that metal-insulator transitions occur rapidly following laser heating. These experiments probe constituents species and solidification kinetics occurring in the early moments of material ejection and provide insight into how particles arise in the current laser ablation regime.

  View details for DOI 10.1103/PhysRevLett.90.236102

  View details for Web of Science ID 000183483500035

  View details for PubMedID 12857274

• Core-level photoemission spectroscopy: Kinetics of cluster formation during femtosecond laser ablation. Glover, E., Ackerman, G., Schoenlein, R. AMER CHEMICAL SOC. 2003: U438

  View details for Web of Science ID 000187918002210

• Development of a longitudinal density monitor for storage rings Zolotorev, M., Beche, J. F., Byrd, J., Datte, P., De Santis, S., Denes, P., Placidi, M., Ratti, A., Riot, Schoenlein, R., Turner, W., Chew, J., Lucas, P., Webber, S. IEEE. 2003: 2530-2532

  View details for Web of Science ID 000189498600800

• A recirculating linac-based facility for ultrafast x-ray science Corlett, J. N., Barletta, W. A., DeSantis, S., Doolittle, L., Fawley, W. M., Green, M. A., Heimann, P., Leone, S., Lidia, S., Li, D., Ratti, A., Robinson, K., Schoenlein, R., Staples, J., Wan, W., Wells, R., Wolski, A., Zholents, A., Parmigiani, F., Placidi, M., Pirkl, W., Rimmer, R. A., Wang, S., Chew, J., Lucas, P., Webber, S. IEEE. 2003: 186-188

  View details for DOI 10.1109/PAC.2003.1288874

  View details for Web of Science ID 000189498600049

• Techniques for synchronization of x-ray pulses to the pump laser in an ultrafast x-ray facility Corlett, J. N., Doolittle, L., Schoenlein, R., Staples, J., Wilcox, R., Zholents, A., Chew, J., Lucas, P., Webber, S. IEEE. 2003: 2408-2410

  View details for Web of Science ID 000189498600759

• Observation of a nearly isotropic, high-energy Coulomb explosion group in the fragmentation of D-2 by short laser pulses PHYSICAL REVIEW A Staudte, A., Cocke, C. L., Prior, A. H., Belkacem, A., Ray, C., Chong, H. W., Glover, T. E., Schoenlein, R. W., Saalmann, U. 2002; 65 (2)

  View details for DOI 10.1103/PhysRevA.65.020703

  View details for Web of Science ID 000173879500003

• Femtosecond X-rays from relativistic electrons: new tools for probing structural dynamics COMPTES RENDUS DE L ACADEMIE DES SCIENCES SERIE IV PHYSIQUE ASTROPHYSIQUE Schoenlein, R. W., Chong, H. H., Glover, T. E., Heimann, P. A., Leemans, W. P., Padmore, H. A., Shank, C. V., Zholents, A. A., Zolotorev, M. S., Corlett, J. S. 2001; 2 (10): 1373-1388

  View details for DOI 10.1016/S1296-2147(01)01277-X

  View details for Web of Science ID 000173968800002

• Ultrafast X-ray diffraction of laser-irradiated crystals 7th International Conference on Synchrotron Radiation Instrumentation (SRI 2000) Heimann, P. A., Lindenberg, A. M., Kang, I., JOHNSON, S., Missalla, T., Chang, Z., Falcone, R. W., Schoenlein, R. W., Glover, T. E., Padmore, H. A. ELSEVIER SCIENCE BV. 2001: 986–989

  View details for Web of Science ID 000171012800037

• Measurement of synchrotron pulse durations using surface photovoltage transients Glover, T. E., Ackermann, G. D., Belkacem, A., Feinberg, B., Heimann, P. A., Hussain, Z., Padmore, H. A., Ray, C., Schoenlein, R. W., Steele, W. F. ELSEVIER SCIENCE BV. 2001: 1438-1440

  View details for DOI 10.1016/S0168-9002(01)00679-9

  View details for Web of Science ID 000171012800145

• High-order harmonic pulse broadening in an ionizing medium PHYSICAL REVIEW A Glover, T. E., Chin, A. H., Schoenlein, R. W. 2001; 63 (2)

  View details for Web of Science ID 000166867900072

• Generation and application of femtosecond X-rays from a synchrotron Schoenlein, R. W., Chong, H. H., Glover, T. E., Heimann, P. A., Shank, C. V., Zholents, A. A., Zolotorev, M. S., IEEE, IEEE IEEE. 2001: 527-528

  View details for Web of Science ID 000175700800264

• Generation of femtosecond X-ray pulses via laser-electron beam interaction APPLIED PHYSICS B-LASERS AND OPTICS Schoenlein, R. W., Chattopadhyay, S., Chong, H. H., Glover, T. E., Heimann, P. A., Leemans, W. P., Shank, C. V., Zholents, A., Zolotorev, M. 2000; 71 (1): 1-10

  View details for Web of Science ID 000165642700001

• Femtosecond X-ray generation through relativistic electron beam-laser interaction COMPTES RENDUS DE L ACADEMIE DES SCIENCES SERIE IV PHYSIQUE ASTROPHYSIQUE Leemans, W., Chattopadhyay, S., Esarey, E., Zholents, A., Zolotorev, M., Chin, A., Schoenlein, R., Shank, C. V. 2000; 1 (3): 279-296

  View details for DOI 10.1016/S1296-2147(00)00149-9

  View details for Web of Science ID 000165215500002

• Generation of femtosecond pulses of synchrotron radiation SCIENCE Schoenlein, R. W., Chattopadhyay, S., Chong, H. H., Glover, T. E., Heimann, P. A., Shank, C. V., Zholents, A. A., Zolotorev, M. S. 2000; 287 (5461): 2237-2240

  Abstract

  Femtosecond synchrotron pulses were generated directly from an electron storage ring. An ultrashort laser pulse was used to modulate the energy of electrons within a 100-femtosecond slice of the stored 30-picosecond electron bunch. The energy-modulated electrons were spatially separated from the long bunch and used to generate approximately 300-femtosecond synchrotron pulses at a bend-magnet beamline, with a spectral range from infrared to x-ray wavelengths. The same technique can be used to generate approximately 100-femtosecond x-ray pulses of substantially higher flux and brightness with an undulator. Such synchrotron-based femtosecond x-ray sources offer the possibility of applying x-ray techniques on an ultrafast time scale to investigate structural dynamics in condensed matter.

  View details for DOI 10.1126/science.287.5461.2237

  View details for Web of Science ID 000086049100043

  View details for PubMedID 10731140

• Time-resolved x-ray photoabsorption and diffraction on timescales from ns to fs 18th International Conference on X-ray and Inner-Shell Processes Heimann, P. A., Missalla, T., Lindenberg, A., Kang, I., JOHNSON, S., Chang, Z., Kapteyn, H. C., Lee, R. W., Falcone, R. W., Schoenlein, R. W., Glover, T. E., Zholents, A. A., Zolotorev, M. S., Padmore, H. A. AMER INST PHYSICS. 2000: 664–668

  View details for Web of Science ID 000086079900052

• Ultrafast structural dynamics in InSb probed by time-resolved X-ray diffraction Chin, A. H., Schoenlein, R. W., Glover, T. E., Balling, P., Leemans, W. P., Shank, C. V., Elsaesser, T., Fujimoto, J. G., Wiersma, D. A., Zinth, W. SPRINGER-VERLAG BERLIN. 1998: 401-403

  View details for Web of Science ID 000082968300120

• Laser based sub-picosecond electron bunch characterization using 90 degrees Thomson scattering Leemans, W. P., Volfbeyn, P., Zolotorev, M., Kim, K. J., Chattopadhyay, S., Schoenlein, R. W., Chin, A. H., Glover, T. E., Balling, P., Shank, C. V., Comyn, M., Craddock, M. K., Reiser, M., Thomson, J. IEEE. 1998: 1984-1986

  View details for Web of Science ID 000079582800638

• Interaction of relativistic electrons with ultrashort laser pulses: Generation of femtosecond X-rays and microprobing of electron beams IEEE JOURNAL OF QUANTUM ELECTRONICS Leemans, W. P., Schoenlein, R. W., Volfbeyn, P., Chin, A. H., Glover, T. E., Balling, P., Zolotorev, M., Kim, K. J., Chattopadhyay, S., Shank, C. V. 1997; 33 (11): 1925-1934

  View details for DOI 10.1109/3.641307

  View details for Web of Science ID A1997YC83800004

• X-ray based subpicosecond electron bunch characterization using 90 degrees Thomson scattering PHYSICAL REVIEW LETTERS Leemans, W. P., Schoenlein, R. W., Volfbeyn, P., Chin, A. H., Glover, T. E., Balling, P., Zolotorev, M., Kim, K. J., Chattopadhyay, S., Shank, C. V. 1996; 77 (20): 4182-4185

  View details for DOI 10.1103/PhysRevLett.77.4182

  View details for Web of Science ID A1996VR55600019

• Femtosecond spectroscopy of a 13-demethylrhodopsin visual pigment analogue: The role of nonbonded interactions in the isomerization process JOURNAL OF PHYSICAL CHEMISTRY Wang, Q., Kochendoerfer, G. G., Schoenlein, R. W., Verdegem, P. J., Lugtenburg, J., Mathies, R. A., Shank, C. V. 1996; 100 (43): 17388-17394

  View details for DOI 10.1021/jp961150s

  View details for Web of Science ID A1996VP26100045

• Femtosecond x-ray pulses at 0.4 angstrom generated by 90 degrees Thomson scattering: A tool for probing the structural dynamics of materials SCIENCE Schoenlein, R. W., Leemans, W. P., Chin, A. H., Volfbeyn, P., Glover, T. E., Balling, P., Zolotorev, M., Kim, K. J., Chattopadhyay, S., Shank, C. V. 1996; 274 (5285): 236-238

  View details for DOI 10.1126/science.274.5285.236

  View details for Web of Science ID A1996VM67100040

• Observation of laser assisted photoelectric effect and femtosecond high order harmonic radiation PHYSICAL REVIEW LETTERS Glover, T. E., Schoenlein, R. W., Chin, A. H., Shank, C. V. 1996; 76 (14): 2468-2471

  View details for DOI 10.1103/PhysRevLett.76.2468

  View details for Web of Science ID A1996UC77700016

• RHODOPSIN PHOTOCHEMISTRY IS VIBRATIONALLY COHERENT MATHIES, R. A., WANG, Q., PETEANU, L. A., SCHOENLEIN, R. W., KOCHENDOERFER, G., SHANK, C. V. AMER CHEMICAL SOC. 1995: 42-PHYS

  View details for Web of Science ID A1995RP25900962

• THE 1ST STEP IN VISION DRIVEN BY A NONBONDED STERIC INTERACTION WANG, Q., KOCHENDOERFER, G. G., VERDEGEM, P. J., LUGTENBURG, J., MATHIES, R. A., SCHOENLEIN, R. W., SHANK, C. V. AMER CHEMICAL SOC. 1995: 67-PHYS

  View details for Web of Science ID A1995QP23300823

• Femtosecond X-ray generation through 90 degrees Thomson scattering: Status of the LBL experiment LEEMANS, W., SCHOENLEIN, R., CHIN, A., GLOVER, E., CONDE, M., CHATTOPADHYAY, S., KIM, K. J., SHANK, C. V., Schoessow, P. AIP PRESS. 1995: 209-223

  View details for Web of Science ID A1995BE17F00015

• VIBRATIONALLY COHERENT PHOTOCHEMISTRY IN THE FEMTOSECOND PRIMARY EVENT OF VISION SCIENCE WANG, Q., SCHOENLEIN, R. W., PETEANU, L. A., MATHIES, R. A., SHANK, C. V. 1994; 266 (5184): 422-424

  Abstract

  Femtosecond pump-probe experiments reveal the impulsive production of photoproduct in the primary event in vision. The retinal chromophore of rhodopsin was excited with a 35-femtosecond pulse at 500 nanometers, and transient changes in absorption were measured with 10-femtosecond probe pulses. At probe wavelengths within the photo-product absorption band, oscillatory features with a period of 550 femtoseconds (60 wavenumbers) were observed whose phase and amplitude demonstrate that they are the result of nonstationary vibrational motion in the ground state of the photoproduct. The observation of coherent vibrational motion of the photoproduct supports the idea that the primary step in vision is a vibrationally coherent process and that the high quantum yield of the cis-->trans isomerization in rhodopsin is a consequence of the extreme speed of the excited-state torsional motion.

  View details for DOI 10.1126/science.7939680

  View details for Web of Science ID A1994PN27200030

  View details for PubMedID 7939680

• FEMTOSECOND VIBRATIONALLY COHERENT PHOTOCHEMISTRY IN RHODOPSIN SHANK, C. V., QUING, W., SCHOENLEIN, R. W., PETEANU, L. A., ROSENTHAL, S. J., MATHIES, R. W. AMER CHEMICAL SOC. 1994: 14-PHYS

  View details for Web of Science ID A1994PA26900627

• QUANTUM-SIZE DEPENDENCE OF FEMTOSECOND ELECTRONIC DEPHASING AND VIBRATIONAL DYNAMICS IN CDSE NANOCRYSTALS PHYSICAL REVIEW B MITTLEMAN, D. M., SCHOENLEIN, R. W., SHIANG, J. J., COLVIN, V. L., ALIVISATOS, A. P., SHANK, C. V. 1994; 49 (20): 14435-14447

  View details for DOI 10.1103/PhysRevB.49.14435

  View details for Web of Science ID A1994NR42300039

  View details for PubMedID 10010526

• THE 1ST STEP IN VISION OCCURS IN FEMTOSECONDS - COMPLETE BLUE AND RED SPECTRAL STUDIES PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA PETEANU, L. A., SCHOENLEIN, R. W., WANG, Q., MATHIES, R. A., SHANK, C. V. 1993; 90 (24): 11762-11766

  Abstract

  Femtosecond transient absorption measurements of the cis-trans isomerization of the visual pigment rhodopsin clarify the interpretation of the dynamics of the first step in vision. We present femtosecond time-resolved spectra as well as kinetic measurements at specific wavelengths between 490 and 670 nm using 10-fs probe pulses centered at 500 and 620 nm following a 35-fs pump pulse at 500 nm. The expanded spectral window beyond that available (500-570 nm) in our previous study [Schoenlein, R. W., Peteanu, L. A., Mathies, R. A. & Shank, C. V. (1991) Science 254, 412-415] provides the full differential absorption spectrum of the photoproduct as a function of delay time after photolysis. The high time-resolution data presented here contradict an alternative interpretation of the rhodopsin photochemistry offered by Callender and co-workers [Yan, M., Manor, D., Weng, G., Chao, H., Rothberg, L., Jedju, T. M., Alfano, R. R. & Callender, R. H. (1991) Proc. Natl. Acad. Sci. USA 88, 9809-9812]. Our results confirm that the red-shifted (lambda max approximately 570 nm) photo-product of the isomerization reaction is fully formed within 200 fs. Subsequent changes in the differential spectra between 200 fs and 6 ps are attributed to a combination of dynamic ground-state processes such as intramolecular vibrational energy redistribution, vibrational cooling, and conformational relaxation.

  View details for DOI 10.1073/pnas.90.24.11762

  View details for Web of Science ID A1993MM51500067

  View details for PubMedID 8265623

  View details for PubMedCentralID PMC48064

• FEMTOSECOND DYNAMICS OF CIS-TRANS ISOMERIZATION IN A VISUAL PIGMENT ANALOG - ISORHODOPSIN JOURNAL OF PHYSICAL CHEMISTRY SCHOENLEIN, R. W., PETEANU, L. A., WANG, Q., MATHIES, R. A., SHANK, C. V. 1993; 97 (46): 12087-12092

  View details for DOI 10.1021/j100148a040

  View details for Web of Science ID A1993MH56300040

• INVESTIGATION OF FEMTOSECOND ELECTRONIC DEPHASING IN CDSE NANOCRYSTALS USING QUANTUM-BEAT-SUPPRESSED PHOTON-ECHOES PHYSICAL REVIEW LETTERS SCHOENLEIN, R. W., MITTLEMAN, D. M., SHIANG, J. J., ALIVISATOS, A. P., SHANK, C. V. 1993; 70 (7): 1014-1017

  View details for DOI 10.1103/PhysRevLett.70.1014

  View details for Web of Science ID A1993KM16600036

• FEMTOSECOND DYNAMICS OF THE CIS-TRANS-ISOMERIZATION IN RHODOPSIN - TE 1ST STEP IN VISION WANG, Q., SCHOENLEIN, R. W., PETEANU, L. A., MATHIES, R. A., SHANK, C. V. BIOPHYSICAL SOCIETY. 1993: A127

  View details for Web of Science ID A1993KP51700723

• ULTRAFAST DYNAMICS OF PHOTOEXCITED C(60) DEXHEIMER, S. L., MITTLEMAN, D. M., SCHOENLEIN, R. W., VAREKA, W. A., XIANG, X. D., ZETTL, A., SHANK, C. V., Gosnell, T. R., Taylor, A. J., Nelson, K. A., Downer, M. C. SPIE - INT SOC OPTICAL ENGINEERING. 1993: 328-332

  View details for DOI 10.1117/12.147065

  View details for Web of Science ID A1993BY83B00034

• GENERATION OF 312-NM, FEMTOSECOND PULSES USING A POLED COPOLYMER FILM IEEE JOURNAL OF QUANTUM ELECTRONICS YANKELEVICH, D. R., DIENES, A., KNOESEN, A., SCHOENLEIN, R. W., SHANK, C. V. 1992; 28 (10): 2398-2403

  View details for DOI 10.1109/3.159546

  View details for Web of Science ID A1992JQ97500045

• K-SPACE CARRIER DYNAMICS IN GAAS APPLIED PHYSICS LETTERS PORTELLA, M. T., BIGOT, J. Y., SCHOENLEIN, R. W., CUNNINGHAM, J. E., SHANK, C. V. 1992; 60 (17): 2123-2125

  View details for DOI 10.1063/1.107083

  View details for Web of Science ID A1992HQ50000028

• FEMTOSECOND PHOTOISOMERIZATION OF RHODOPSIN AS THE PRIMARY EVENT IN VISION SCHOENLEIN, R. W., SHANK, C. V., PETEANU, L. A., MATHIES, R. A., LAUBEREAU, A., SEILMEIER, A. IOP PUBLISHING LTD. 1992: 583-588

  View details for Web of Science ID A1992BW54B00131

• THE 1ST STEP IN VISION - FEMTOSECOND ISOMERIZATION OF RHODOPSIN SCIENCE SCHOENLEIN, R. W., PETEANU, L. A., MATHIES, R. A., SHANK, C. V. 1991; 254 (5030): 412-415

  Abstract

  The kinetics of the primary event in vision have been resolved with the use of femtosecond optical measurement techniques. The 11-cis retinal prosthetic group of rhodopsin is excited with a 35-femtosecond pump pulse at 500 nanometers, and the transient changes in absorption are measured between 450 and 580 nanometers with a 10-femtosecond probe pulse. Within 200 femtoseconds, an increased absorption is observed between 540 and 580 nanometers, indicating the formation of photoproduct on this time scale. These measurements demonstrate that the first step in vision, the 11-cis----11-trans torsional isomerization of the rhodopsin chromophore, is essentially complete in only 200 femtoseconds.

  View details for DOI 10.1126/science.1925597

  View details for Web of Science ID A1991GK72900043

  View details for PubMedID 1925597

• 2-DIMENSIONAL CARRIER-CARRIER SCREENING IN A QUANTUM-WELL PHYSICAL REVIEW LETTERS BIGOT, J. Y., PORTELLA, M. T., SCHOENLEIN, R. W., CUNNINGHAM, J. E., SHANK, C. V. 1991; 67 (5): 636-639

  View details for DOI 10.1103/PhysRevLett.67.636

  View details for Web of Science ID A1991FY50500029

• NON-MARKOVIAN DEPHASING OF MOLECULES IN SOLUTION MEASURED WITH 3-PULSE FEMTOSECOND PHOTON-ECHOES PHYSICAL REVIEW LETTERS BIGOT, J. Y., PORTELLA, M. T., SCHOENLEIN, R. W., BARDEEN, C. J., MIGUS, A., SHANK, C. V. 1991; 66 (9): 1138-1141

  View details for DOI 10.1103/PhysRevLett.66.1138

  View details for Web of Science ID A1991FA34900009

• GENERATION OF BLUE-GREEN 10 FS PULSES USING AN EXCIMER PUMPED DYE AMPLIFIER APPLIED PHYSICS LETTERS SCHOENLEIN, R. W., BIGOT, J. Y., PORTELLA, M. T., SHANK, C. V. 1991; 58 (8): 801-803

  View details for DOI 10.1063/1.104494

  View details for Web of Science ID A1991EZ14200006

• FEMTOSECOND RELAXATION DYNAMICS OF IMAGE-POTENTIAL STATES PHYSICAL REVIEW B SCHOENLEIN, R. W., FUJIMOTO, J. G., EESLEY, G. L., CAPEHART, T. W. 1991; 43 (6): 4688-4698

  View details for DOI 10.1103/PhysRevB.43.4688

  View details for Web of Science ID A1991EY62300015

  View details for PubMedID 9997837

• RESONANT INTERVALLEY SCATTERING IN GAAS PHYSICAL REVIEW LETTERS BIGOT, J. Y., PORTELLA, M. T., SCHOENLEIN, R. W., CUNNINGHAM, J. E., SHANK, C. V. 1990; 65 (27): 3429-3432

  View details for DOI 10.1103/PhysRevLett.65.3429

  View details for Web of Science ID A1990EQ33800018

• FEMTOSECOND EXCITED-STATE DYNAMICS OF POLYDIACETYLENE APPLIED PHYSICS LETTERS HUXLEY, J. M., MATALONI, P., SCHOENLEIN, R. W., FUJIMOTO, J. G., IPPEN, E. P., CARTER, G. M. 1990; 56 (16): 1600-1602

  View details for DOI 10.1063/1.103140

  View details for Web of Science ID A1990DA48400030

• FEMTOSECOND DYNAMICS OF THE N = 2 IMAGE-POTENTIAL STATE ON AG(100) PHYSICAL REVIEW B SCHOENLEIN, R. W., FUJIMOTO, J. G., EESLEY, G. L., CAPEHART, T. W. 1990; 41 (8): 5436-5439

  View details for DOI 10.1103/PhysRevB.41.5436

  View details for Web of Science ID A1990CU94400075

  View details for PubMedID 9994417

• AMPLIFICATION OF FEMTOSECOND PULSES IN TI-AL2O3 USING AN INJECTION-SEEDED LASER OPTICS LETTERS LAGASSE, M. J., SCHOENLEIN, R. W., FUJIMOTO, J. G., SCHULZ, P. A. 1989; 14 (24): 1347-1349

  Abstract

  A 440-fsec, 0.1-pJ pulse from a dye laser is injected into a high-repetition-rate Ti:Al(2)O(3) laser pumped by a copper-vapor laser to study the amplification and pulse broadening of femtosecond pulses in Ti:Al(2)O(3). Gains of 2 x 10(7) are achieved with output pulse durations of 1.1 psec. After recompression with a grating pair to compensate dispersion broadening, pulses as short as 275 fsec are obtained.

  View details for DOI 10.1364/OL.14.001347

  View details for Web of Science ID A1989CE68900003

  View details for PubMedID 19759678

• FEMTOSECOND STUDIES OF INTERVALLEY SCATTERING IN GAAS AND ALXGA1-XAS BAILEY, D. W., STANTON, C. J., HESS, K., LAGASSE, M. J., SCHOENLEIN, R. W., FUJIMOTO, J. G. PERGAMON-ELSEVIER SCIENCE LTD. 1989: 1491-1495

  View details for DOI 10.1016/0038-1101(89)90262-1

  View details for Web of Science ID A1989CN60400074

• CORNEAL ABLATION BY NANOSECOND, PICOSECOND, AND FEMTOSECOND LASERS AT 532 AND 625 NM ARCHIVES OF OPHTHALMOLOGY STERN, D., SCHOENLEIN, R. W., PULIAFITO, C. A., DOBI, E. T., BIRNGRUBER, R., FUJIMOTO, J. G. 1989; 107 (4): 587-592

  Abstract

  We produced corneal excisions with nanosecond (ns)-, picosecond-, and femtosecond (fs)-pulsed lasers at visible wavelengths. The threshold energy for ablation was proportional to the square root of the pulse duration and varied from 2.5 microjoules (microJ) at 100 fs to 500 microJ at 8 ns. Excisions made with picosecond and femtosecond lasers was ultrastructurally superior to those made with nanosecond lasers and, at pulse energies near threshold, showed almost as little tissue damage as excisions made with excimer lasers at 193 nm. We conclude that ultrashort-pulsed lasers at visible and near-infrared wavelengths are a possible alternative to excimer lasers for corneal surgery and might have advantages over conventional ophthalmic neodymium-YAG lasers for some intraocular applications.

  View details for DOI 10.1001/archopht.1989.01070010601038

  View details for Web of Science ID A1989U097800031

  View details for PubMedID 2705929

• FEMTOSECOND STUDIES OF IMAGE-POTENTIAL DYNAMICS IN METALS PHYSICAL REVIEW LETTERS SCHOENLEIN, R. W., FUJIMOTO, J. G., EESLEY, G. L., CAPEHART, T. W. 1988; 61 (22): 2596-2599

  View details for DOI 10.1103/PhysRevLett.61.2596

  View details for Web of Science ID A1988R004400023

• FEMTOSECOND HOT CARRIER ENERGY REDISTRIBUTION IN GAAS AND ALGAAS SOLID-STATE ELECTRONICS SCHOENLEIN, R. W., LIN, W. Z., BRORSON, S. D., IPPEN, E. P., FUJIMOTO, J. G. 1988; 31 (3-4): 443-446

  View details for DOI 10.1016/0038-1101(88)90314-0

  View details for Web of Science ID A1988M469100031

• FEMTOSECOND ABSORPTION SATURATION STUDIES OF HOT CARRIERS IN GAAS AND ALGAAS IEEE JOURNAL OF QUANTUM ELECTRONICS LIN, W. Z., SCHOENLEIN, R. W., FUJIMOTO, J. G., IPPEN, E. P. 1988; 24 (2): 267-275

  View details for DOI 10.1109/3.123

  View details for Web of Science ID A1988M671200019

• FEMTOSECOND HOT-CARRIER ENERGY RELAXATION IN GAAS APPLIED PHYSICS LETTERS SCHOENLEIN, R. W., LIN, W. Z., IPPEN, E. P., FUJIMOTO, J. G. 1987; 51 (18): 1442-1444

  View details for DOI 10.1063/1.98651

  View details for Web of Science ID A1987K600300019

• FEMTOSECOND LASER TISSUE INTERACTIONS - RETINAL INJURY STUDIES IEEE JOURNAL OF QUANTUM ELECTRONICS BIRNGRUBER, R., PULIAFITO, C. A., GAWANDE, A., LIN, W. Z., SCHOENLEIN, R. W., FUJIMOTO, J. G. 1987; 23 (10): 1836-1844

  View details for DOI 10.1109/JQE.1987.1073235

  View details for Web of Science ID A1987K351000021

• FEMTOSECOND STUDIES OF NONEQUILIBRIUM ELECTRONIC PROCESSES IN METALS PHYSICAL REVIEW LETTERS SCHOENLEIN, R. W., LIN, W. Z., FUJIMOTO, J. G., EESLEY, G. L. 1987; 58 (16): 1680-1683

  View details for DOI 10.1103/PhysRevLett.58.1680

  View details for Web of Science ID A1987G882400024