Academic Appointments


  • Emeritus Faculty, Acad Council, SLAC General Program

Honors & Awards


  • Davisson-Germer Prize in Atomic and Surface Physics, American Physical Society (2011)

Projects


2021-22 Courses


All Publications


  • Stimulated resonant inelastic X-ray scattering in a solid COMMUNICATIONS PHYSICS Higley, D. J., Chen, Z., Beye, M., Hantschmann, M., Reid, A. H., Mehta, V., Hellwig, O., Dakovski, G. L., Mitra, A., Engel, R. Y., Maxwell, T., Ding, Y., Bonetti, S., Bucher, M., Carron, S., Chase, T., Jal, E., Kukreja, R., Liu, T., Foehlisch, A., Durr, H. A., Schlotter, W. F., Stohr, J. 2022; 5 (1)
  • Femtosecond X-ray induced changes of the electronic and magnetic response of solids from electron redistribution. Nature communications Higley, D. J., Reid, A. H., Chen, Z., Guyader, L. L., Hellwig, O., Lutman, A. A., Liu, T., Shafer, P., Chase, T., Dakovski, G. L., Mitra, A., Yuan, E., Schlappa, J., Durr, H. A., Schlotter, W. F., Stohr, J. 2019; 10 (1): 5289

    Abstract

    Resonant X-ray absorption, where an X-ray photon excites a core electron into an unoccupied valence state, is an essential process in many standard X-ray spectroscopies. With increasing X-ray intensity, the X-ray absorption strength is expected to become nonlinear. Here, we report the onset of such a nonlinearity in the resonant X-ray absorption of magnetic Co/Pd multilayers near the Co L[Formula: see text] edge. The nonlinearity is directly observed through the change of the absorption spectrum, which is modified in less than 40 fs within 2 eV of its threshold. This is interpreted as a redistribution of valence electrons near the Fermi level. For our magnetic sample this also involves mixing of majority and minority spins, due to sample demagnetization. Our findings reveal that nonlinear X-ray responses of materials may already occur at relatively low intensities, where the macroscopic sample is not destroyed, providing insight into ultrafast charge and spin dynamics.

    View details for DOI 10.1038/s41467-019-13272-5

    View details for PubMedID 31754109

  • Spin-current-mediated rapid magnon localisation and coalescence after ultrafast optical pumping of ferrimagnetic alloys NATURE COMMUNICATIONS Iacocca, E., Liu, T., Reid, A. H., Fu, Z., Ruta, S., Granitzka, P. W., Jai, E., Bonetti, S., Gray, A. X., Graves, C. E., Kukreja, R., Chen, Z., Higley, D. J., Chase, T., Le Guyader, L., Hirsch, K., Ohldag, H., Schlotter, W. F., Dakovski, G. L., Coslovich, G., Hoffmann, M. C., Carron, S., Tsukamoto, A., Kirilyuk, A., Kime, A., Rasing, T., Stohr, J., Evans, R. L., Ostler, T., Chantrell, R. W., Hoefer, M. A., Silva, T. J., Durr, H. A. 2019; 10: 1756

    Abstract

    Sub-picosecond magnetisation manipulation via femtosecond optical pumping has attracted wide attention ever since its original discovery in 1996. However, the spatial evolution of the magnetisation is not yet well understood, in part due to the difficulty in experimentally probing such rapid dynamics. Here, we find evidence of a universal rapid magnetic order recovery in ferrimagnets with perpendicular magnetic anisotropy via nonlinear magnon processes. We identify magnon localisation and coalescence processes, whereby localised magnetic textures nucleate and subsequently interact and grow in accordance with a power law formalism. A hydrodynamic representation of the numerical simulations indicates that the appearance of noncollinear magnetisation via optical pumping establishes exchange-mediated spin currents with an equivalent 100% spin polarised charge current density of 107 A cm-2. Such large spin currents precipitate rapid recovery of magnetic order after optical pumping. The magnon processes discussed here provide new insights for the stabilization of desired meta-stable states.

    View details for DOI 10.1038/s41467-019-09577-0

    View details for Web of Science ID 000464494100025

    View details for PubMedID 30988403

    View details for PubMedCentralID PMC6465265

  • Overcoming the diffraction limit by multi-photon interference: a tutorial ADVANCES IN OPTICS AND PHOTONICS Stohr, J. 2019; 11 (1): 215–313
  • Ultrafast Self-Induced X-Ray Transparency and Loss of Magnetic Diffraction PHYSICAL REVIEW LETTERS Chen, Z., Higley, D. J., Beye, M., Hantschmann, M., Mehta, Hellwig, O., Mitra, A., Bonetti, S., Bucher, M., Carron, S., Chase, T., Jal, E., Kukreja, R., Liu, T., Reid, A. H., Dakovski, G. L., Foehlisch, A., Schlotter, W. F., Duerr, H. A., Stoehr, J. 2018; 121 (13): 137403

    Abstract

    Using ultrafast ≃2.5  fs and ≃25  fs self-amplified spontaneous emission pulses of increasing intensity and a novel experimental scheme, we report the concurrent increase of stimulated emission in the forward direction and loss of out-of-beam diffraction contrast for a Co/Pd multilayer sample. The experimental results are quantitatively accounted for by a statistical description of the pulses in conjunction with the optical Bloch equations. The dependence of the stimulated sample response on the incident intensity, coherence time, and energy jitter of the employed pulses reveals the importance of increased control of x-ray free electron laser radiation.

    View details for DOI 10.1103/PhysRevLett.121.137403

    View details for Web of Science ID 000446294100002

    View details for PubMedID 30312105

  • Beyond a phenomenological description of magnetostriction (vol 9, 388, 2018) NATURE COMMUNICATIONS Reid, A. H., Shen, X., Maldonado, P., Chase, T., Jal, E., Granitzka, P. W., Carva, K., Li, R. K., Li, J., Wu, L., Vecchione, T., Liu, T., Chen, Z., Higley, D. J., Hartmann, N., Coffee, R., Wu, J., Dakowski, G. L., Schlotter, W. F., Ohldag, H., Takahashi, Y. K., Mehta, V., Hellwig, O., Fry, A., Zhu, Y., Cao, J., Fullerton, E. E., Stohr, J., Oppeneer, P. M., Wang, X. J., Durr, H. A. 2018; 9: 1035

    Abstract

    "The technical support from SLAC Accelerator Directorate, Technology Innovation Directorate, LCLS laser division and Test Facility Division is gratefully acknowledged. We thank S.P. Weathersby, R.K. Jobe, D. McCormick, A. Mitra, S. Carron and J. Corbett for their invaluable help and technical assistance. Research at SLAC was supported through the SIMES Institute which like the LCLS and SSRL user facilities is funded by the Office of Basic Energy Sciences of the U.S. Department of Energy under Contract No. DE-AC02-76SF00515. The UED work was performed at SLAC MeV-UED, which is supported in part by the DOE BES SUF Division Accelerator & Detector R&D program, the LCLS Facility, and SLAC under contract Nos. DE-AC02-05-CH11231 and DE-AC02-76SF00515. Use of the Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515."and"Work at BNL was supported by DOE BES Materials Science and Engineering Division under Contract No: DE-AC02-98CH10886. J.C. would like to acknowledge the support from National Science Foundation Grant No. 1207252. E.E.F. would like to acknowledge support from the U.S. Department of Energy (DOE), Office of Basic Energy Sciences (BES) under Award No. DE-SC0003678."This has been corrected in both the PDF and HTML versions of the Article.

    View details for PubMedID 29515124

  • Magnetic Switching in Granular FePt Layers Promoted by Near-Field Laser Enhancement NANO LETTERS Granitzka, P. W., Jal, E., Le Guyader, L., Savoini, M., Higley, D. J., Liu, T., Chen, Z., Chase, T., Ohldag, H., Dakovski, G. L., Schlotter, W. F., Carron, S., Hoffman, M. C., Gray, A. X., Shafer, P., Arenholz, E., Hellwig, O., Mehta, V., Takahashi, Y. K., Wang, J., Fullerton, E. E., Stoehr, J., Reid, A. H., Duerr, H. A. 2017; 17 (4): 2426-2432

    Abstract

    Light-matter interaction at the nanoscale in magnetic materials is a topic of intense research in view of potential applications in next-generation high-density magnetic recording. Laser-assisted switching provides a pathway for overcoming the material constraints of high-anisotropy and high-packing density media, though much about the dynamics of the switching process remains unexplored. We use ultrafast small-angle X-ray scattering at an X-ray free-electron laser to probe the magnetic switching dynamics of FePt nanoparticles embedded in a carbon matrix following excitation by an optical femtosecond laser pulse. We observe that the combination of laser excitation and applied static magnetic field, 1 order of magnitude smaller than the coercive field, can overcome the magnetic anisotropy barrier between "up" and "down" magnetization, enabling magnetization switching. This magnetic switching is found to be inhomogeneous throughout the material with some individual FePt nanoparticles neither switching nor demagnetizing. The origin of this behavior is identified as the near-field modification of the incident laser radiation around FePt nanoparticles. The fraction of not-switching nanoparticles is influenced by the heat flow between FePt and a heat-sink layer.

    View details for DOI 10.1021/acs.nanolett.7b00052

    View details for Web of Science ID 000399354500047

    View details for PubMedID 28272897

  • Two-Photon X-Ray Diffraction PHYSICAL REVIEW LETTERS Stohr, J. 2017; 118 (2)

    Abstract

    The interference pattern of a circular photon source has long been used to define the optical diffraction limit. Here we show the breakdown of conventional x-ray diffraction theory for the fundamental case of a "source," consisting of a back-illuminated thin film in a circular aperture. When the conventional spontaneous x-ray scattering by atoms in the film is replaced at high incident intensity by stimulated resonant scattering, the film becomes the source of cloned photon twins and the diffraction pattern becomes self-focussed beyond the diffraction limit. The case of cloned x-ray biphotons is compared to and distinguished from the much studied case of entangled optical biphotons.

    View details for DOI 10.1103/PhysRevLett.118.024801

    View details for Web of Science ID 000391926900007

    View details for PubMedID 28128585

  • Elimination of X-Ray Diffraction through Stimulated X-Ray Transmission PHYSICAL REVIEW LETTERS Wu, B., Wang, T., Graves, C. E., Zhu, D., Schlotter, W. F., Turner, J. J., Hellwig, O., Chen, Z., Duerr, H. A., Scherz, A., Stohr, J. 2016; 117 (2)

    Abstract

    X-ray diffractive imaging with laterally coherent x-ray free-electron laser (XFEL) pulses is increasingly utilized to obtain ultrafast snapshots of matter. Here we report the amazing disappearance of single-shot charge and magnetic diffraction patterns recorded with resonantly tuned, narrow bandwidth XFEL pulses. Our experimental results reveal the exquisite sensitivity of single-shot charge and magnetic diffraction patterns of a magnetic film to the onset of field-induced stimulated elastic x-ray forward scattering. The loss in diffraction contrast, measured over 3 orders of magnitude in intensity, is in remarkable quantitative agreement with a recent theory that is extended to include diffraction.

    View details for DOI 10.1103/PhysRevLett.117.027401

    View details for Web of Science ID 000379728400011

    View details for PubMedID 27447522

  • Femtosecond X-ray magnetic circular dichroism absorption spectroscopy at an X-ray free electron laser REVIEW OF SCIENTIFIC INSTRUMENTS Higley, D. J., Hirsch, K., Dakovski, G. L., Jal, E., Yuan, E., Liu, T., Lutman, A. A., MacArthur, J. P., Arenholz, E., Chen, Z., Coslovich, G., Denes, P., Granitzka, P. W., Hart, P., Hoffmann, M. C., Joseph, J., Le Guyader, L., Mitra, A., Moeller, S., Ohldag, H., Seaberg, M., Shafer, P., Stoehr, J., Tsukamoto, A., Nuhn, H., Reid, A. H., Duerr, H. A., Schlotter, W. F. 2016; 87 (3)

    Abstract

    X-ray magnetic circular dichroism spectroscopy using an X-ray free electron laser is demonstrated with spectra over the Fe L(3,2)-edges. The high brightness of the X-ray free electron laser combined with high accuracy detection of incident and transmitted X-rays enables ultrafast X-ray magnetic circular dichroism studies of unprecedented sensitivity. This new capability is applied to a study of all-optical magnetic switching dynamics of Fe and Gd magnetic sublattices in a GdFeCo thin film above its magnetization compensation temperature.

    View details for DOI 10.1063/1.4944410

    View details for Web of Science ID 000373713300011

    View details for PubMedID 27036761

  • Direct observation and imaging of a spin-wave soliton with p-like symmetry NATURE COMMUNICATIONS Bonetti, S., Kukreja, R., Chen, Z., Macia, F., Hernandez, J. M., Eklund, A., Backes, D., Frisch, J., Katine, J., Malm, G., Urazhdin, S., Kent, A. D., Stoehr, J., Ohldag, H., Duerr, H. A. 2015; 6: 8889

    Abstract

    Spin waves, the collective excitations of spins, can emerge as nonlinear solitons at the nanoscale when excited by an electrical current from a nanocontact. These solitons are expected to have essentially cylindrical symmetry (that is, s-like), but no direct experimental observation exists to confirm this picture. Using a high-sensitivity time-resolved magnetic X-ray microscopy with 50 ps temporal resolution and 35 nm spatial resolution, we are able to create a real-space spin-wave movie and observe the emergence of a localized soliton with a nodal line, that is, with p-like symmetry. Micromagnetic simulations explain the measurements and reveal that the symmetry of the soliton can be controlled by magnetic fields. Our results broaden the understanding of spin-wave dynamics at the nanoscale, with implications for the design of magnetic nanodevices.

    View details for DOI 10.1038/ncomms9889

    View details for Web of Science ID 000366296800003

    View details for PubMedID 26567699

    View details for PubMedCentralID PMC4660209

  • Nanoscale Confinement of All-Optical Magnetic Switching in TbFeCo - Competition with Nanoscale Heterogeneity NANO LETTERS Liu, T., Wang, T., Reid, A. H., Savoini, M., Wu, X., Koene, B., Granitzka, P., Graves, C. E., Higley, D. J., Chen, Z., Razinskas, G., Hantschmann, M., Scherz, A., Stoehr, J., Tsukarnote, A., Hecht, B., Kimel, A. V., Kirilyuk, A., Rasing, T., Duerr, H. A. 2015; 15 (10): 6862-6868

    Abstract

    Single femtosecond optical laser pulses, of sufficient intensity, are demonstrated to reverse magnetization in a process known as all-optical switching. Gold two-wire antennas are placed on the all-optical switching film TbFeCo. These structures are resonant with the optical field, and they create a field enhancement in the near-field which confines the area where optical switching can occur. The magnetic switching that occurs around and below the antenna is imaged using resonant X-ray holography and magnetic circular dichroism. The results not only show the feasibility of controllable switching with antenna assistance but also demonstrate the highly inhomogeneous nature of the switching process, which is attributed to the process depending on the material's heterogeneity.

    View details for DOI 10.1021/acs.nanolett.5b02743

    View details for Web of Science ID 000363003100087

  • Creation of X-Ray Transparency of Matter by Stimulated Elastic Forward Scattering PHYSICAL REVIEW LETTERS Stoer, J., Scherz, A. 2015; 115 (10)
  • Microwave soft x-ray microscopy for nanoscale magnetization dynamics in the 5-10 GHz frequency range REVIEW OF SCIENTIFIC INSTRUMENTS Bonetti, S., Kukreja, R., Chen, Z., Spoddig, D., Ollefs, K., Schoeppner, C., Meckenstock, R., Ney, A., Pinto, J., Houanche, R., Frisch, J., Stoehr, J., Duerr, H. A., Ohldag, H. 2015; 86 (9)

    Abstract

    We present a scanning transmission x-ray microscopy setup combined with a novel microwave synchronization scheme for studying high frequency magnetization dynamics at synchrotron light sources. The sensitivity necessary to detect small changes in the magnetization on short time scales and nanometer spatial dimensions is achieved by combining the excitation mechanism with single photon counting electronics that is locked to the synchrotron operation frequency. Our instrument is capable of creating direct images of dynamical phenomena in the 5-10 GHz range, with high spatial resolution. When used together with circularly polarized x-rays, the above capabilities can be combined to study magnetic phenomena at microwave frequencies, such as ferromagnetic resonance (FMR) and spin waves. We demonstrate the capabilities of our technique by presenting phase resolved images of a ∼6 GHz nanoscale spin wave generated by a spin torque oscillator, as well as the uniform ferromagnetic precession with ∼0.1° amplitude at ∼9 GHz in a micrometer-sized cobalt strip.

    View details for DOI 10.1063/1.4930007

    View details for Web of Science ID 000362573300023

    View details for PubMedID 26429444

  • X-ray Detection of Transient Magnetic Moments Induced by a Spin Current in Cu PHYSICAL REVIEW LETTERS Kukreja, R., Bonetti, S., Chen, Z., Backes, D., Acremann, Y., Katine, J. A., Kent, A. D., Duerr, H. A., Ohldag, H., Stoehr, J. 2015; 115 (9): 096601

    Abstract

    We have used a MHz lock-in x-ray spectromicroscopy technique to directly detect changes in magnetic moment of Cu due to spin injection from an adjacent Co layer. The elemental and chemical specificity of x rays allows us to distinguish two spin current induced effects. We detect the creation of transient magnetic moments of 3×10^{-5}μ_{B} on Cu atoms within the bulk of the 28 nm thick Cu film due to spin accumulation. The moment value is compared to predictions by Mott's two current model. We also observe that the hybridization induced existing magnetic moments at the Cu interface atoms are transiently increased by about 10% or 4×10^{-3}μ_{B} per atom. This reveals the dominance of spin-torque alignment over Joule heat induced disorder of the interfacial Cu moments during current flow.

    View details for DOI 10.1103/PhysRevLett.115.096601

    View details for Web of Science ID 000359947900005

    View details for PubMedID 26371670

  • Extracting magnetic cluster size and its distributions in advanced perpendicular recording media with shrinking grain size using small angle x-ray scattering APPLIED PHYSICS LETTERS Mehta, V., Wang, T., Ikeda, Y., Takano, K., Terris, B. D., Wu, B., Graves, C., Duerr, H. A., Scherz, A., Stoehr, J., Hellwig, O. 2015; 106 (20)

    View details for DOI 10.1063/1.4921403

    View details for Web of Science ID 000355009400025

  • Magnetic design evolution in perpendicular magnetic recording media as revealed by resonant small angle x-ray scattering APPLIED PHYSICS LETTERS Wang, T., Mehta, V., Ikeda, Y., Do, H., Takano, K., Florez, S., Terris, B. D., Wu, B., Graves, C., Shu, M., Rick, R., Scherz, A., Stoehr, J., Hellwig, O. 2013; 103 (11)

    View details for DOI 10.1063/1.4820921

    View details for Web of Science ID 000324495000043

  • Nanoscale spin reversal by non-local angular momentum transfer following ultrafast laser excitation in ferrimagnetic GdFeCo NATURE MATERIALS Graves, C. E., Reid, A. H., Wang, T., Wu, B., de Jong, S., Vahaplar, K., Radu, I., Bernstein, D. P., Messerschmidt, M., Mueller, L., Coffee, R., Bionta, M., Epp, S. W., Hartmann, R., Kimmel, N., Hauser, G., Hartmann, A., Holl, P., Gorke, H., Mentink, J. H., Tsukamoto, A., Fognini, A., Turner, J. J., Schlotter, W. F., Rolles, D., Soltau, H., Strueder, L., Acremann, Y., Kimel, A. V., Kirilyuk, A., Rasing, T., Stoehr, J., Scherz, A. O., Duerr, H. A. 2013; 12 (4): 293-298

    Abstract

    Ultrafast laser techniques have revealed extraordinary spin dynamics in magnetic materials that equilibrium descriptions of magnetism cannot explain. Particularly important for future applications is understanding non-equilibrium spin dynamics following laser excitation on the nanoscale, yet the limited spatial resolution of optical laser techniques has impeded such nanoscale studies. Here we present ultrafast diffraction experiments with an X-ray laser that probes the nanoscale spin dynamics following optical laser excitation in the ferrimagnetic alloy GdFeCo, which exhibits macroscopic all-optical switching. Our study reveals that GdFeCo displays nanoscale chemical and magnetic inhomogeneities that affect the spin dynamics. In particular, we observe Gd spin reversal in Gd-rich nanoregions within the first picosecond driven by the non-local transfer of angular momentum from larger adjacent Fe-rich nanoregions. These results suggest that a magnetic material's microstructure can be engineered to control transient laser-excited spins, potentially allowing faster (~ 1 ps) spin reversal than in present technologies.

    View details for DOI 10.1038/NMAT3597

    View details for Web of Science ID 000317164900015

  • Femtosecond Single-Shot Imaging of Nanoscale Ferromagnetic Order in Co/Pd Multilayers Using Resonant X-Ray Holography PHYSICAL REVIEW LETTERS Wang, T., Zhu, D., Wu, B., Graves, C., Schaffert, S., Rander, T., Mueller, L., Vodungbo, B., Baumier, C., Bernstein, D. P., Braeuer, B., Cros, V., de Jong, S., Delaunay, R., Fognini, A., Kukreja, R., Lee, S., Lopez-Flores, V., Mohanty, J., Pfau, B., Popescu, H., Sacchi, M., Sardinha, A. B., Sirotti, F., Zeitoun, P., Messerschmidt, M., Turner, J. J., Schlotter, W. F., Hellwig, O., Mattana, R., Jaouen, N., Fortuna, F., Acremann, Y., Gutt, C., Duerr, H. A., Beaurepaire, E., Boeglin, C., Eisebitt, S., Gruebel, G., Luening, J., Stoehr, J., Scherz, A. O. 2012; 108 (26)

    Abstract

    We present the first single-shot images of ferromagnetic, nanoscale spin order taken with femtosecond x-ray pulses. X-ray-induced electron and spin dynamics can be outrun with pulses shorter than 80 fs in the investigated fluence regime, and no permanent aftereffects in the samples are observed below a fluence of 25 mJ/cm(2). Employing resonant spatially muliplexed x-ray holography results in a low imaging threshold of 5 mJ/cm(2). Our results open new ways to combine ultrafast laser spectroscopy with sequential snapshot imaging on a single sample, generating a movie of excited state dynamics.

    View details for DOI 10.1103/PhysRevLett.108.267403

    View details for PubMedID 23005013

  • Nonuniform switching of the perpendicular magnetization in a spin-torque-driven magnetic nanopillar PHYSICAL REVIEW B Bernstein, D. P., Braeuer, B., Kukreja, R., Stoehr, J., Hauet, T., Cucchiara, J., Mangin, S., Katine, J. A., Tyliszczak, T., Chou, K. W., Acremann, Y. 2011; 83 (18)
  • High-Resolution X-Ray Lensless Imaging by Differential Holographic Encoding PHYSICAL REVIEW LETTERS Zhu, D., Guizar-Sicairos, M., Wu, B., Scherz, A., Acremann, Y., Tyliszczak, T., Fischer, P., Friedenberger, N., Ollefs, K., Farle, M., Fienup, J. R., Stoehr, J. 2010; 105 (4)

    Abstract

    We demonstrate in the soft x-ray regime a novel technique for high-resolution lensless imaging based on differential holographic encoding. We have achieved superior resolution over x-ray Fourier transform holography while maintaining the signal-to-noise ratio and algorithmic simplicity. We obtain a resolution of 16 nm by synthesizing images in the Fourier domain from a single diffraction pattern, which allows resolution improvement beyond the reference fabrication limit. Direct comparisons with iterative phase retrieval and images from state-of-the-art zone-plate microscopes are presented.

    View details for DOI 10.1103/PhysRevLett.105.043901

    View details for Web of Science ID 000280125300003

    View details for PubMedID 20867843

  • Holographic x-ray image reconstruction through the application of differential and integral operators OPTICS LETTERS Guizar-Sicairos, M., Zhu, D., Fienup, J. R., Wu, B., Scherz, A., Stoehr, J. 2010; 35 (7): 928–30

    Abstract

    We introduce a noniterative image-reconstruction technique for coherent diffractive imaging. Through the application of differential and integral operators, an extended reference can be used to recover the complex-valued transmissivity of an object, in closed form, from a measurement of its far-field (Fraunhofer) diffraction intensity. We demonstrate the feasibility of this approach, using a reference of a pair of crossed wires and slits, through numerical simulations and a soft x-ray coherent diffractive imaging experiment.

    View details for DOI 10.1364/OL.35.000928

    View details for Web of Science ID 000276309300012

    View details for PubMedID 20364172

  • Phase retrieval in x-ray lensless holography by reference beam tuning OPTICS LETTERS Zhu, D., Wu, B., Rick, R., Stoehr, J., Scherz, A. 2009; 34 (17): 2604-2606

    Abstract

    We show the ability to determine the relative phase between the object and a reference scatterer by tuning the overall intensity and phase of the reference wave. The proposed reference-guided phase retrieval algorithm uses the relative phase as a constraint to iteratively reconstruct the object and the reference simultaneously, and thus does not require precisely defined reference structures. The algorithm also features rapid and reliable convergence and overcomes the uniqueness problem. The method is demonstrated by a soft-x-ray coherent imaging experiment that utilizes a large micrometer-sized reference structure that can be turned on and off, yielding an object image with resolution close to the reconstruction pixel size of 21 nm.

    View details for Web of Science ID 000270114400022

    View details for PubMedID 19724505

  • Magnetization switching without charge or spin currents APPLIED PHYSICS LETTERS Stohr, J., Siegmann, H. C., Kashuba, A., Gamble, S. J. 2009; 94 (7)

    View details for DOI 10.1063/1.3081421

    View details for Web of Science ID 000263599200046

  • An amplifier concept for spintronics APPLIED PHYSICS LETTERS Acremann, Y., Yu, X. W., Tulapurkar, A. A., Scherz, A., Chembrolu, V., Katine, J. A., Carey, M. J., Siegmann, H. C., Stohr, J. 2008; 93 (10)

    View details for DOI 10.1063/1.2977964

    View details for Web of Science ID 000259797000066

  • Phase imaging of magnetic nanostructures using resonant soft x-ray holography PHYSICAL REVIEW B Scherz, A., Schlotter, W. F., Chen, K., Rick, R., Stohr, J., Luning, J., Mcnulty, I., Guenther, C., Radu, F., Eberhardt, W., Hellwig, O., Eisebitt, S. 2007; 76 (21)
  • Software defined photon counting system for time resolved x-ray experiments REVIEW OF SCIENTIFIC INSTRUMENTS Acremann, Y., Chembrolu, V., Strachan, J. P., Tyliszczak, T., Stohr, J. 2007; 78 (1)

    Abstract

    The time structure of synchrotron radiation allows time resolved experiments with sub-100 ps temporal resolution using a pump-probe approach. However, the relaxation time of the samples may require a lower repetition rate of the pump pulse compared to the full repetition rate of the x-ray pulses from the synchrotron. The use of only the x-ray pulse immediately following the pump pulse is not efficient and often requires special operation modes where only a few buckets of the storage ring are filled. We designed a novel software defined photon counting system that allows to implement a variety of pump-probe schemes at the full repetition rate. The high number of photon counters allows to detect the response of the sample at multiple time delays simultaneously, thus improving the efficiency of the experiment. The system has been successfully applied to time resolved scanning transmission x-ray microscopy. However, this technique is applicable more generally.

    View details for DOI 10.1063/1.2428274

    View details for Web of Science ID 000243892300039

    View details for PubMedID 17503937

  • Extended field of view soft x-ray Fourier transform holography: toward imaging ultrafast evolution in a single shot. Optics letters Schlotter, W. F., Lüning, J. n., Rick, R. n., Chen, K. n., Scherz, A. n., Eisebitt, S. n., Günther, C. M., Eberhardt, W. n., Hellwig, O. n., Stöhr, J. n. 2007; 32 (21): 3110–12

    Abstract

    Panoramic full-field imaging is demonstrated by applying spatial multiplexing to Fourier transform holography. Multiple object and reference waves extend the effective field of view for lensless imaging without compromising the spatial resolution. In this way, local regions of interest distributed throughout a sample can be simultaneously imaged with high spatial resolution. A method is proposed for capturing multiple ultrafast images of a sample with a single x-ray pulse.

    View details for PubMedID 17975613

  • Time-resolved imaging of spin transfer switching: Beyond the macrospin concept PHYSICAL REVIEW LETTERS Acremann, Y., Strachan, J. P., Chembrolu, V., Andrews, S. D., Tyliszczak, T., Katine, J. A., Carey, M. J., Clemens, B. M., Siegmann, H. C., Stohr, J. 2006; 96 (21)

    Abstract

    Time-resolved images of the magnetization switching process in a spin transfer structure, obtained by ultrafast x-ray microscopy, reveal the limitations of the macrospin model. Instead of a coherent magnetization reversal, we observe switching by lateral motion of a magnetic vortex across a nanoscale element. Our measurements reveal the fundamental roles played independently by the torques due to charge and spin currents in breaking the magnetic symmetry on picosecond time scales.

    View details for DOI 10.1103/PhysRevLett.96.217202

    View details for Web of Science ID 000238004000051

    View details for PubMedID 16803270

  • Parallel versus antiparallel interfacial coupling in exchange biased Co/FeF2 PHYSICAL REVIEW LETTERS Ohldag, H., Shi, H., Arenholz, E., Stohr, J., Lederman, D. 2006; 96 (2)

    Abstract

    By using the surface and element specificity of soft x-ray magnetic dichroism we provide direct experimental evidence for two different types of interfacial uncompensated Fe moments in exchange biased Co/FeF2 bilayers. Some moments are pinned and coupled antiparallel to the ferromagnet (FM). They give rise to a positive exchange bias and vanish above T(N) = 78 together with the antiferromagnet (AF) order. Other interfacial Fe moments are unpinned and coupled parallel to the FM. They persist up to 300 K and give rise to magnetic order at the AF surface even above T(N) .

    View details for DOI 10.1103/PhysRevLett.96.027203

    View details for Web of Science ID 000234758100081

    View details for PubMedID 16486624

  • Dissipation of spin angular momentum in magnetic switching PHYSICAL REVIEW LETTERS Stamm, C., Tudosa, I., Siegmann, H. C., Stohr, J., Dobin, A. Y., Woltersdorf, G., Heinrich, B., Vaterlaus, A. 2005; 94 (19)

    Abstract

    Applying one ultrashort magnetic field pulse, we observe up to 10 precessional switches of the magnetization direction in single crystalline Fe films of 10 and 15 atomic layers. We find that the rate at which angular momentum is dissipated in uniform large angle spin precession increases with time and film thickness, surpassing the intrinsic ferromagnetic resonance spin lattice relaxation of Fe by nearly an order of magnitude.

    View details for DOI 10.1103/PhysRevLett.94.197603

    View details for Web of Science ID 000229277000059

    View details for PubMedID 16090212

  • An x-ray photoemission electron microscope using an electron mirror aberration corrector for the study of complex materials 4th International Conference on LEEM/PEEM Feng, J., Forest, E., MacDowell, A. A., Marcus, M., Padmore, H., Raoux, S., Robin, D., Scholl, A., Schlueter, R., Schmid, P., Stohr, J., Wan, W., Wei, D. H., Wu, Y. IOP PUBLISHING LTD. 2005: S1339–S1350
  • Lensless imaging of magnetic nanostructures by X-ray spectro-holography NATURE Eisebitt, S., Luning, J., Schlotter, W. F., Lorgen, M., Hellwig, O., Eberhardt, W., Stohr, J. 2004; 432 (7019): 885-888

    Abstract

    Our knowledge of the structure of matter is largely based on X-ray diffraction studies of periodic structures and the successful transformation (inversion) of the diffraction patterns into real-space atomic maps. But the determination of non-periodic nanoscale structures by X-rays is much more difficult. Inversion of the measured diffuse X-ray intensity patterns suffers from the intrinsic loss of phase information, and direct imaging methods are limited in resolution by the available X-ray optics. Here we demonstrate a versatile technique for imaging nanostructures, based on the use of resonantly tuned soft X-rays for scattering contrast and the direct Fourier inversion of a holographically formed interference pattern. Our implementation places the sample behind a lithographically manufactured mask with a micrometre-sized sample aperture and a nanometre-sized hole that defines a reference beam. As an example, we have used the resonant X-ray magnetic circular dichroism effect to image the random magnetic domain structure in a Co/Pt multilayer film with a spatial resolution of 50 nm. Our technique, which is a form of Fourier transform holography, is transferable to a wide variety of specimens, appears scalable to diffraction-limited resolution, and is well suited for ultrafast single-shot imaging with coherent X-ray free-electron laser sources.

    View details for DOI 10.1038/nature03139

    View details for Web of Science ID 000225733500048

    View details for PubMedID 15602557

  • Domain-size-dependent exchange bias in Co/LaFeO3 APPLIED PHYSICS LETTERS Scholl, A., Nolting, F., Seo, J. W., Ohldag, H., Stohr, J., Raoux, S., Locquet, J. P., Fompeyrine, J. 2004; 85 (18): 4085-4087

    View details for DOI 10.1063/1.1813633

    View details for Web of Science ID 000224894900043

  • Creation of an antiferromagnetic exchange spring PHYSICAL REVIEW LETTERS Scholl, A., Liberati, M., Arenholz, E., Ohldag, H., Stohr, J. 2004; 92 (24)

    Abstract

    We present evidence for the creation of an exchange spring in an antiferromagnet due to exchange coupling to a ferromagnet. X-ray magnetic linear dichroism spectroscopy on single crystal Co/NiO(001) shows that a partial domain wall is wound up at the surface of the antiferromagnet when the adjacent ferromagnet is rotated by a magnetic field. We determine the interface exchange stiffness and the antiferromagnetic domain wall energy from the field dependence of the direction of the antiferromagnetic axis, the antiferromagnetic pendant to a ferromagnetic hysteresis loop. The existence of a planar antiferromagnetic domain wall, proven by our measurement, is a key assumption of most exchange bias models.

    View details for DOI 10.1103/PhysRevLett.92.247201

    View details for Web of Science ID 000222112900057

    View details for PubMedID 15245128

  • Future possibilities of the Linac Coherent Light Source JOURNAL OF SYNCHROTRON RADIATION Cornacchia, M., ARTHUR, J., Bane, K., Bolton, P., Carr, R., Decker, F. J., Emma, P., Galayda, J., Hastings, J., Hodgson, K., Huang, Z., LINDAU, I., Nuhn, H. D., Paterson, J. M., Pellegrini, C., Reiche, S., Schlarb, H., Stohr, J., Stupakov, G., Walz, D., Winick, H. 2004; 11: 227-238

    Abstract

    A study of the potential for the development of the Linac Coherent Light Source (LCLS) beyond the specifications of the baseline design is presented. These future developments include delivery of X-ray pulses in the 1 fs regime, extension of the spectral range, increase of the FEL power, exploitation of the spontaneous emission, and a more flexible time structure. As this potential is exploited, the LCLS can maintain its role as a world-leading instrument for many years beyond its commissioning in 2008 and initial operation as the world's first X-ray free-electron laser.

    View details for DOI 10.1107/S090904950400370X

    View details for Web of Science ID 000220974600001

    View details for PubMedID 15103109

  • Scalable approach for lensless imaging at x-ray wavelengths APPLIED PHYSICS LETTERS Eisebitt, S., Lorgen, M., Eberhardt, W., Luning, J., Andrews, S., Stohr, J. 2004; 84 (17): 3373-3375

    View details for DOI 10.1063/1.1728320

    View details for Web of Science ID 000220958100051

  • The ultimate speed of magnetic switching in granular recording media NATURE Tudosa, I., Stamm, C., Kashuba, A. B., King, F., Siegmann, H. C., Stohr, J., Ju, G., Lu, B., Weller, D. 2004; 428 (6985): 831-833

    Abstract

    In magnetic memory devices, logical bits are recorded by selectively setting the magnetization vector of individual magnetic domains either 'up' or 'down'. In such devices, the fastest and most efficient recording method involves precessional switching: when a magnetic field B(p) is applied as a write pulse over a period tau, the magnetization vector precesses about the field until B(p)tau reaches the threshold value at which switching occurs. Increasing the amplitude of the write pulse B(p) might therefore substantially shorten the required switching time tau and allow for faster magnetic recording. Here we use very short pulses of a very high magnetic field to show that under these extreme conditions, precessional switching in magnetic media supporting high bit densities no longer takes place at well-defined field strengths; instead, switching occurs randomly within a wide range of magnetic fields. We attribute this behaviour to a momentary collapse of the ferromagnetic order of the spins under the load of the short and high-field pulse, thus establishing an ultimate limit to the speed of deterministic switching and magnetic recording.

    View details for DOI 10.1038/nature02438

    View details for Web of Science ID 000220952300033

    View details for PubMedID 15103370

  • Vortex core-driven magnetization dynamics SCIENCE Choe, S. B., Acremann, Y., Scholl, A., Bauer, A., Doran, A., Stohr, J., Padmore, H. A. 2004; 304 (5669): 420-422

    Abstract

    Time-resolved x-ray imaging shows that the magnetization dynamics of a micron-sized pattern containing a ferromagnetic vortex is determined by its handedness, or chirality. The out-of-plane magnetization in the nanometer-scale vortex core induces a three-dimensional handedness in the planar magnetic structure, leading to a precessional motion of the core parallel to a subnanosecond field pulse. The core velocity was an order of magnitude higher than expected from the static susceptibility. These results demonstrate that handedness, already well known to be important in biological systems, plays an important role in the dynamics of microscopic magnets.

    View details for Web of Science ID 000220845400042

    View details for PubMedID 15087545

  • Polarization effects in coherent scattering from magnetic specimen: Implications for x-ray holography, lensless imaging, and correlation spectroscopy PHYSICAL REVIEW B Eisebitt, S., Lorgen, M., Eberhardt, W., Luning, J., Stohr, J., Rettner, C. T., Hellwig, O., Fullerton, E. E., Denbeaux, G. 2003; 68 (10)
  • Correlation between exchange bias and pinned interfacial spins PHYSICAL REVIEW LETTERS Ohldag, H., Scholl, A., Nolting, F., Arenholz, E., Maat, S., Young, A. T., Carey, M., Stohr, J. 2003; 91 (1)

    Abstract

    Using x-ray magnetic circular dichroism, we have detected the very interfacial spins that are responsible for the horizontal loop shift in three different exchange bias sandwiches, chosen because of their potential for device applications. The "pinned" uncompensated interfacial spins constitute only a fraction of a monolayer and do not rotate in an external magnetic field since they are tightly locked to the antiferromagnetic lattice. A simple extension of the Meiklejohn and Bean model is proposed to account quantitatively for the exchange bias fields in the three studied systems from the experimentally determined number of pinned moments and their sizes.

    View details for DOI 10.1103/PhysRevLett.91.017203

    View details for Web of Science ID 000183915400050

    View details for PubMedID 12906569

  • Determination of the antiferromagnetic spin axis in epitaxial LaFeO3 films by x-ray magnetic linear dichroism spectroscopy PHYSICAL REVIEW B Luning, J., Nolting, F., Scholl, A., Ohldag, H., Seo, J. W., Fompeyrine, J., Locquet, J. P., Stohr, J. 2003; 67 (21)
  • X-ray photoemission electron microscopy, a tool for the investigation of complex magnetic structures (invited) 12th National Synchrotron Radiation Instrumentation Conference Scholl, A., Ohldag, H., Nolting, F., Stohr, J., Padmore, H. A. AMER INST PHYSICS. 2002: 1362–66

    View details for DOI 10.1063/1.1445485

    View details for Web of Science ID 000174182800003

  • Spectroscopic identification and direct imaging of interfacial magnetic spins PHYSICAL REVIEW LETTERS Ohldag, H., Regan, T. J., Stohr, J., Scholl, A., Nolting, F., Luning, J., Stamm, C., Anders, S., White, R. L. 2001; 87 (24)

    Abstract

    Using x-ray absorption spectromicroscopy we have imaged the uncompensated spins induced at the surface of antiferromagnetic (AFM) NiO(100) by deposition of ferromagnetic (FM) Co. These spins align parallel to the AFM spins in NiO(100) and align the FM spins in Co. The uncompensated interfacial spins arise from an ultrathin CoNiOx layer that is formed upon Co deposition through reduction of the NiO surface. The interfacial Ni spins are discussed in terms of the "uncompensated spins" at AFM/FM interfaces long held responsible for coercivity increases and exchange bias. We find a direct correlation between their number and the size of the coercivity.

    View details for DOI 10.1103/PhysRevLett.87.247201

    View details for Web of Science ID 000172642100052

    View details for PubMedID 11736537

  • Importance of structural order for the low surface energy of perfluoroalkyl substituted polymethacrylates JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA Luning, J., Yoon, D. Y., Stohr, J. 2001; 121 (1-3): 265-279
  • Chemical effects at metal/oxide interfaces studied by x-ray-absorption spectroscopy PHYSICAL REVIEW B Regan, T. J., Ohldag, H., Stamm, C., Nolting, F., Luning, J., Stohr, J., White, R. L. 2001; 64 (21)
  • Liquid crystal alignment on carbonaceous surfaces with orientational order SCIENCE Stohr, J., Samant, M. G., Luning, J., Callegari, A. C., Chaudhari, P., Doyle, J. P., Lacey, J. A., Lien, S. A., Purushothaman, S., Speidell, J. L. 2001; 292 (5525): 2299-2302

    Abstract

    We used near-edge x-ray absorption fine structure (NEXAFS) spectroscopy to link the orientational bond order at three carbonaceous surfaces-rubbed polyimide, ion beam-irradiated polyimide, and ion beam-irradiated diamondlike carbon films-with the direction of liquid crystal (LC) alignment on these surfaces. We show that, in general, LC alignment can be created on any carbonaceous substrate by inducing orientational order at its surface. Our results form the scientific basis for LC alignment layers consisting of amorphous carbon films in which orientational order near the surface is induced by a directional low-energy ion beam.

    View details for Web of Science ID 000169455900048

    View details for PubMedID 11423654

  • Exploring the microscopic origin of exchange bias with photoelectron emission microscopy (invited) 8th Joint MMM/Intermag Conference Scholl, A., Nolting, F., Stohr, J., Regan, T., Luning, J., Seo, J. W., Locquet, J. P., Fompeyrine, J., Anders, S., Ohldag, H., Padmore, H. A. AMER INST PHYSICS. 2001: 7266–68
  • Spin reorientation at the antiferromagnetic NiO(001) surface in response to an adjacent ferromagnet PHYSICAL REVIEW LETTERS Ohldag, H., Scholl, A., Nolting, F., Anders, S., Hillebrecht, F. U., Stohr, J. 2001; 86 (13): 2878-2881

    Abstract

    Polarization dependent x-ray photoemission electron microscopy was used to investigate the spin structure near the surface of an antiferromagnetic NiO(001) single crystal in response to the deposition of a thin ferromagnetic Co film. For the cleaved NiO surface we observe only a subset of bulklike antiferromagnetic domains which is attributed to minimization of dipolar energies. Upon Co deposition a spin reorientation near the NiO interface occurs, with the antiferromagnetic spins rotating in plane, parallel to the spins of the Co layer. Our results demonstrate that the spin configuration in an antiferromagnet near its interface with a ferromagnet may significantly deviate from that in the bulk antiferromagnet.

    View details for Web of Science ID 000167693000045

    View details for PubMedID 11290062

  • Studies of the magnetic structure at the ferromagnet-antiferromagnet interface 11th International Conference on X-ray Absorption Fine Structure (XAFS XI) Scholl, A., Nolting, F., Stohr, J., Luning, J., Seo, J. W., Locquet, J. P., Fompeyrine, J., Anders, S., Ohldag, H., Padmore, H. A. WILEY-BLACKWELL. 2001: 101–104

    Abstract

    Antiferromagnetic layers are a scientifically challenging component in magnetoelectronic devices, such as magnetic sensors in hard-disk heads, or magnetic random-access memory (RAM) elements. In this paper, it is shown that photoelectron emission microscopy (PEEM) is capable of determining the magnetic structure at the interface of ferromagnets and antiferromagnets with high spatial resolution (down to 20 nm). Dichroism effects at the L edges of the magnetic 3d transition metals, using circularly or linearly polarized soft X-rays from a synchrotron source, give rise to a magnetic image contrast. Images, acquired with the PEEM2 experiment at the Advanced Light Source, show magnetic contrast for antiferromagnetic LaFeO3, microscopically resolving the magnetic domain structure in an antiferromagnetically ordered thin film for the first time. Magnetic coupling between LaFeO3 and an adjacent Co layer results in a complete correlation of their magnetic domain structures. From field-dependent measurements, a unidirectional anisotropy resulting in a local exchange bias of up to 30 Oe in single domains could be deduced. The elemental specificity and the quantitative magnetic sensitivity render PEEM a perfect tool to study magnetic coupling effects in multilayered thin-film samples.

    View details for Web of Science ID 000167298100012

    View details for PubMedID 11512704

  • Correlation of surface and bulk order in low surface energy polymers MACROMOLECULES Luning, J., Stohr, J., Song, K. Y., Hawker, C. J., Iodice, P., Nguyen, C. V., Yoon, D. Y. 2001; 34 (5): 1128-1130

    View details for DOI 10.1021/ma0001584

    View details for Web of Science ID 000167136000002

  • X-ray spectro-microscopy of complex materials and surfaces IBM JOURNAL OF RESEARCH AND DEVELOPMENT Stohr, J., Anders, S. 2000; 44 (4): 535-551
  • Images of the antiferromaguetic structure of a NiO(100) surface by means of X-ray magnetic linear dichroism spectromicroscopy PHYSICAL REVIEW LETTERS Stohr, J., Scholl, A., Regan, T. J., Anders, S., Luning, J., Scheinfein, M. R., Padmore, H. A., White, R. L. 1999; 83 (9): 1862-1865
  • Electron-yield saturation effects in L-edge x-ray magnetic circular dichroism spectra of Fe, Co, and Ni PHYSICAL REVIEW B Nakajima, R., Stohr, J., Idzerda, Y. U. 1999; 59 (9): 6421-6429
  • Magnetic properties of transition metal multilayers studied with X-ray magnetic circular dichroism spectroscopy IBM JOURNAL OF RESEARCH AND DEVELOPMENT Stohr, J., Nakajima, R. 1998; 42 (1): 73-88
  • X-ray photoemission electron microscopy for the study of semiconductor materials International Conference on Characterization and Metrology for ULSI Technology Anders, S., Stammler, T., Padmore, H. A., Terminello, L. J., Jankowski, A. F., Stohr, J., Diaz, J., Cossy-Favre, A., Singh, S. AIP PRESS. 1998: 873–877
  • X-ray magnetic circular dichroism spectroscopy of transition metal multilayers 9th International Conference on X-Ray Absorption Fine Structure Stohr, J., Nakajima, R. EDP SCIENCES S A. 1997: 47–57
  • X-ray magnetic circular dichroism study of the induced spin polarization of Cu in Co/Cu and Fe/Cu multilayers ZEITSCHRIFT FUR PHYSIK B-CONDENSED MATTER Held, G. A., Samant, M. G., Stohr, J., Parkin, S. S., Hermsmeier, B. D., VANSCHILFGAARDE, M., Nakajima, R. 1996; 100 (3): 335-341
  • MICROSCOPIC ORIGIN OF MAGNETIC-ANISOTROPY IN AU/CO/AU PROBED WITH X-RAY MAGNETIC CIRCULAR-DICHROISM PHYSICAL REVIEW LETTERS Weller, D., Stohr, J., Nakajima, R., Carl, A., Samant, M. G., Chappert, C., Megy, R., Beauvillain, P., Veillet, P., Held, G. A. 1995; 75 (20): 3752-3755
  • THE EFFECT OF SUBSURFACE OXYGEN ON THE ORIENTATION OF MOLECULAR-OXYGEN ON AG(110) SURFACE SCIENCE PAWELACREW, J., Madix, R. J., Stohr, J. 1995; 339 (1-2): 23-28
  • INDUCED SPIN POLARIZATION IN CU SPACER LAYERS IN CO/CU MULTILAYERS PHYSICAL REVIEW LETTERS Samant, M. G., Stohr, J., Parkin, S. S., Held, G. A., Hermsmeier, B. D., HERMAN, F., VANSCHILFGAARDE, M., Duda, L. C., Mancini, D. C., Wassdahl, N., Nakajima, R. 1994; 72 (7): 1112-1115
  • THE ORIENTATION AND ELECTRONIC-STRUCTURE OF 1,3-BUTADIENE ADSORBED AND CONDENSED ON AG(110) - A NEXAFS STUDY SURFACE SCIENCE COULMAN, D., Solomon, J. L., Madix, R. J., Stohr, J. 1991; 257 (1-3): 97-102
  • CHEMISORPTION-INDUCED CHANGES IN THE X-RAY-ABSORPTION FINE-STRUCTURE OF ADSORBED SPECIES PHYSICAL REVIEW LETTERS Stevens, P. A., UPTON, T. H., Stohr, J., Madix, R. J. 1991; 67 (12): 1653-1656
  • ORIENTATION AND ABSOLUTE COVERAGE OF BENZENE, ANILINE, AND PHENOL ON AG(110) DETERMINED BY NEXAFS AND XPS SURFACE SCIENCE Solomon, J. L., Madix, R. J., Stohr, J. 1991; 255 (1-2): 12-30
  • NEXAFS AND EELS STUDY OF THE ORIENTATION OF SULFUR-DIOXIDE ON AG(110) JOURNAL OF PHYSICAL CHEMISTRY Solomon, J. L., Madix, R. J., Wurth, W., Stohr, J. 1991; 95 (9): 3687-3691
  • ORIENTATION AND ABSOLUTE COVERAGE OF FURAN AND 2,5-DIHYDROFURAN ON AG(110) DETERMINED BY NEAR EDGE X-RAY ABSORPTION FINE-STRUCTURE AND X-RAY PHOTOELECTRON-SPECTROSCOPY JOURNAL OF CHEMICAL PHYSICS Solomon, J. L., Madix, R. J., Stohr, J. 1991; 94 (5): 4012-4023
  • ORIENTATION OF ETHYLENE AND PROPYLENE ON AG(110) FROM NEAR EDGE X-RAY ADSORPTION FINE-STRUCTURE JOURNAL OF CHEMICAL PHYSICS Solomon, J. L., Madix, R. J., Stohr, J. 1990; 93 (11): 8379-8382
  • A CRITICAL-INTERPRETATION OF THE NEAR-EDGE X-RAY ABSORPTION FINE-STRUCTURE OF CHEMISORBED BENZENE SURFACE SCIENCE Liu, A. C., Stohr, J., Friend, C. M., Madix, R. J. 1990; 235 (2-3): 107-115
  • NEXAFS STUDY OF HCOO/AG(110) - EVIDENCE FOR DYNAMIC BENDING SURFACE SCIENCE Stevens, P. A., Madix, R. J., Stohr, J. 1990; 230 (1-3): 1-12
  • THE BONDING OF ACETONITRILE AND CH2CN ON AG(110) DETERMINED BY NEAR EDGE X-RAY ABSORPTION FINE-STRUCTURE - EVIDENCE FOR PI-DONOR BONDING AND AZIMUTHAL ORDERING JOURNAL OF CHEMICAL PHYSICS Stevens, P. A., Madix, R. J., Stohr, J. 1989; 91 (7): 4338-4345
  • PI-BONDED INTERMEDIATES IN ALCOHOL OXIDATION - ORIENTATIONS OF ALLYLOXY AND PROPARGYLOXY ON AG(110) BY NEAR EDGE X-RAY ABSORPTION FINE-STRUCTURE JOURNAL OF CHEMICAL PHYSICS Solomon, J. L., Madix, R. J., Stohr, J. 1988; 89 (8): 5316-5322
  • EXTENDED X-RAY-ABSORPTION FINE-STRUCTURE STUDIES OF DIAMOND AND GRAPHITE PHYSICAL REVIEW B Comelli, G., Stohr, J., Jark, W., Pate, B. B. 1988; 37 (9): 4383-4389
  • NEXAFS STUDIES OF COMPLEX ALCOHOLS AND CARBOXYLIC-ACIDS ON THE SI(111)(7X7) SURFACE SURFACE SCIENCE OUTKA, D. A., Stohr, J., Madix, R. J., Rotermund, H. H., HERMSMEIER, B., Solomon, J. 1987; 185 (1-2): 53-74
  • NEAR-EDGE STRUCTURE OF OXYGEN IN INORGANIC OXIDES: EFFECT OF LOCAL GEOMETRY AND CATION TYPE JOURNAL DE PHYSIQUE Brown, G. E., WAYCHUNAS, G. A., Stohr, J., Sette, F. 1986; 47 (C-8): 163-167
  • EVIDENCE FOR A NOVEL CHEMISORPTION BOND - FORMATE (HCO2) ON CU (100) PHYSICAL REVIEW LETTERS Stohr, J., OUTKA, D. A., Madix, R. J., DOBLER, U. 1985; 54 (12): 1256-1259
  • CORE HOLE SCREENING AND LIFETIMES IN ADSORBATES ON METALLIC SURFACES SOLID STATE COMMUNICATIONS Eberhardt, W., Stohr, J., OUTKA, D., Madix, R. J. 1985; 54 (6): 493-496
  • AUGER AND PHOTOELECTRON CONTRIBUTIONS TO THE ELECTRON-YIELD SURFACE EXTENDED X-RAY-ABSORPTION FINE-STRUCTURE SIGNAL PHYSICAL REVIEW B Stohr, J., Noguera, C., Kendelewicz, T. 1984; 30 (10): 5571-5579
  • A NEW WIGGLER BEAM LINE FOR SSRL NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH Hoyer, E., Bahr, C., Chan, T., Chin, J., Elioff, T., Halbach, K., Harnett, G., Humphries, D., HUNT, D., Kim, K. J., Lauritzen, T., Lindle, D., Shirley, D., TAFELSKI, R., Thompson, A., Cramer, S., Eisenberger, P., Hewitt, R., Stohr, J., Boyce, R., Brown, G., GOLDE, A., Gould, R., Hower, N., LINDAU, I., Winick, H., Yang, J., Harris, J., Scott, B. 1983; 208 (1-3): 117-125
  • STRUCTURE OF THE AG ON SI(111) 7X7 INTERFACE BY MEANS OF SURFACE EXAFS SURFACE SCIENCE Stohr, J., Jaeger, R., Rossi, G., Kendelewicz, T., LINDAU, I. 1983; 134 (3): 813-835
  • BONDING AND BOND LENGTHS OF CHEMISORBED MOLECULES FROM NEAR-EDGE X-RAY-ABSORPTION FINE-STRUCTURE STUDIES PHYSICAL REVIEW LETTERS Stohr, J., Gland, J. L., Eberhardt, W., OUTKA, D., Madix, R. J., Sette, F., KOESTNER, R. J., DOEBLER, U. 1983; 51 (26): 2414-2417
  • X-RAY-INDUCED ELECTRON-STIMULATED DESORPTION VERSUS PHOTON STIMULATED DESORPTION - NH3 ON NI(110) SURFACE SCIENCE Jaeger, R., Stohr, J., Kendelewicz, T. 1983; 134 (2): 547-565
  • K-SHELL EXCITATION OF D2O AND H2O ICE - PHOTOION AND PHOTOELECTRON YIELDS PHYSICAL REVIEW B Rosenberg, R. A., LAROE, P. R., REHN, V., Stohr, J., Jaeger, R., Parks, C. C. 1983; 28 (6): 3026-3030
  • PERFORMANCE AND APPLICATION OF A DOUBLE CRYSTAL MONOCHROMATOR IN THE ENERGY REGION 800 LESS-THAN-OR-EQUAL-TO HV LESS-THAN-OR-EQUAL-TO 4500 EV NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH Hussain, Z., Umbach, E., Shirley, D. A., Stohr, J., Feldhaus, J. 1982; 195 (1-2): 115-131
  • STRUCTURE OF P(2X2) AND C(2X2) OXYGEN ON NI(100) - A SURFACE EXTENDED-X-RAY ABSORPTION FINE-STRUCTURE STUDY PHYSICAL REVIEW LETTERS Stohr, J., Jaeger, R., Kendelewicz, T. 1982; 49 (2): 142-146
  • EVIDENCE FOR MULTI-ELECTRON EXCITATIONS IN PHOTON STIMULATED ION DESORPTION - CO AND NO ON NI(100) SURFACE SCIENCE Jaeger, R., Treichler, R., Stohr, J. 1982; 117 (1-3): 533-548
  • ORIENTATION OF CHEMISORBED MOLECULES FROM SURFACE-ABSORPTION FINE-STRUCTURE MEASUREMENTS - CO AND NO ON NI(100) PHYSICAL REVIEW LETTERS Stohr, J., Baberschke, K., Jaeger, R., Treichler, R., Brennan, S. 1981; 47 (5): 381-384
  • PHOTON-STIMULATED DESORPTION DUE TO MULTIELECTRON EXCITATIONS IN CHEMISORBED MOLECULES - CO ON NI(100) PHYSICAL REVIEW LETTERS Jaeger, R., Stohr, J., Treichler, R., Baberschke, K. 1981; 47 (18): 1300-1304
  • STRUCTURAL MODELS FOR THE INTERACTION OF OXYGEN WITH AL(111) AND AL IMPLIED BY PHOTOEMISSION AND SURFACE EXAFS SURFACE SCIENCE Norman, D., Brennan, S., Jaeger, R., Stohr, J. 1981; 105 (2-3): L297-L306
  • PHOTON-STIMULATED DESORPTION FOLLOWING DEEP CORE-LEVEL EXCITATION - O ON MO(100) PHYSICAL REVIEW B Jaeger, R., Stohr, J., Feldhaus, J., Brennan, S. 1981; 23 (5): 2102-2110
  • EXTENDED ABSORPTION FINE-STRUCTURE STUDIES ABOVE THE CARBON, NITROGEN, OXYGEN, AND FLUORINE-K ABSORPTION EDGES APPLIED OPTICS Stohr, J., Jaeger, R., Feldhaus, J., Brennan, S., Norman, D., Apai, G. 1980; 19 (23): 3911-3919

    Abstract

    Absorption measurements above the K edges of the low-Z atoms, C, N, O, and F, are discussed, which utilize 250-1000-eV synchrotron radiation. The paper emphasizes experimental procedures of soft x-ray absorption and extended absorption fine structure (EXAFS) measurements as well as applications and future prospects of such studies. In particular, we discuss such applications as surface EXAFS, surface absorption fine structure, and ion yield EXAFS measurements.

    View details for Web of Science ID A1980KS97200008

    View details for PubMedID 20234715

  • CARBON K-EDGE FINE-STRUCTURE IN GRAPHITE FOILS AND IN THIN-FILM CONTAMINANTS ON METAL-SURFACES PHYSICAL REVIEW B DENLEY, D., Perfetti, P., Williams, R. S., Shirley, D. A., Stohr, J. 1980; 21 (6): 2267-2273
  • CORE-LEVEL BINDING-ENERGY SHIFTS DUE TO RECONSTRUCTION ON THE SI(111) 2X1 SURFACE PHYSICAL REVIEW LETTERS Brennan, S., Stohr, J., Jaeger, R., Rowe, J. E. 1980; 45 (17): 1414-1418
  • SURFACE EXTENDED-X-RAY-ABSORPTION-FINE-STRUCTURE STUDY OF OXYGEN INTERACTION WITH AL(111) SURFACES PHYSICAL REVIEW B Stohr, J., Johansson, L. I., Brennan, S., Hecht, M., Miller, J. N. 1980; 22 (8): 4052-4065
  • SURFACE EXTENDED-X-RAY-ABSORPTION FINE-STRUCTURE BY MEANS OF PHOTON-STIMULATED ION DESORPTION - O ON MO(100) PHYSICAL REVIEW LETTERS Jaeger, R., Feldhaus, J., Haase, J., Stohr, J., Hussain, Z., Menzel, D., Norman, D. 1980; 45 (23): 1870-1873
  • OXYGEN INTERACTION WITH AL(111) - A SURFACE EXTENDED X-RAY ABSORPTION FINE-STRUCTURE STUDY APPLIED SURFACE SCIENCE Johansson, L. I., Stohr, J., Brennan, S. 1980; 6 (3-4): 419-429
  • SOFT-X-RAY ABSORPTION-SPECTROSCOPY - ELECTRONIC AND MORPHOLOGICAL STRUCTURE OF POLY(VINYLIDENE FLUORIDE) JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Williams, R. S., DENLEY, D., Shirley, D. A., Stohr, J. 1980; 102 (18): 5717-5723
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  • SURFACE EXAFS INVESTIGATION OF OXYGEN-CHEMISORPTION ON GAAS(110) JOURNAL OF VACUUM SCIENCE & TECHNOLOGY Stohr, J., BAUER, R. S., MCMENAMIN, J. C., Johansson, L. I., Brennan, S. 1979; 16 (5): 1195-1199
  • EXTENDED X-RAY-ABSORPTION FINE-STRUCTURE OF SMALL CU AND NI CLUSTERS - BINDING-ENERGY AND BOND-LENGTH CHANGES WITH CLUSTER SIZE PHYSICAL REVIEW LETTERS Apai, G., Hamilton, J. F., Stohr, J., Thompson, A. 1979; 43 (2): 165-169
  • EXAFS STUDIES OF THE BONDING GEOMETRY OF OXYGEN ON SI(111) USING ELECTRON YIELD DETECTION JOURNAL OF VACUUM SCIENCE & TECHNOLOGY Stohr, J., Johansson, L. I., LINDAU, I., Pianetta, P. 1979; 16 (5): 1221-1224
  • EXTENDED-X-RAY-ABSORPTION-FINE-STRUCTURE STUDIES OF LOW-Z ATOMS IN SOLIDS AND ON SURFACES - STUDIES OF SI3N4, SIO2, AND OXYGEN ON SI(111) PHYSICAL REVIEW B Stohr, J., Johansson, L., LINDAU, I., Pianetta, P. 1979; 20 (2): 664-680
  • BONDING OF OXYGEN ON A1(111) - SURFACE EXTENDED X-RAY ABSORPTION FINE-STRUCTURE STUDY PHYSICAL REVIEW LETTERS Johansson, L. I., Stohr, J. 1979; 43 (25): 1882-1885
  • 2ND UHV BEAM LINE AT SSRL FOR STUDIES IN SPECTRAL RANGE 4-4000 EV NUCLEAR INSTRUMENTS & METHODS Stohr, J., REHN, V., LINDAU, I., BACHRACH, R. Z. 1978; 152 (1): 43-51
  • SURFACE EXTENDED X-RAY ABSORPTION FINE-STRUCTURE IN THE SOFT-X-RAY REGION - STUDY OF AN OXIDIZED AL SURFACE PHYSICAL REVIEW B Stohr, J., DENLEY, D., Perfetti, P. 1978; 18 (8): 4132-4135
  • SURFACE EXAFS STUDIES USING ELECTRON YIELD SPECTROSCOPY - OXYGEN ON NI (100) JAPANESE JOURNAL OF APPLIED PHYSICS Stohr, J. 1978; 17: 217-220