Matthias Kling
Director, PULSE Institute, Professor of Photon Science and, by courtesy, of Applied Physics
Photon Science Directorate
Bio
Matthias Kling is an expert in ultrafast science, serving as Professor of Photon Science and Applied Physics (by courtesy) at Stanford University and Director of the Stanford PULSE Institute at SLAC National Accelerator Laboratory. With a background spanning physics, laser physics, and physical chemistry, he earned degrees from the Universities of Göttingen and Jena before completing postdoctoral research at UC Berkeley and AMOLF in Amsterdam. From 2007 to 2021, he led a research group within the Laboratory of Attosecond Physics at the Max Planck Institute of Quantum Optics and held faculty positions at Kansas State University and the University of Munich. Matthias joined SLAC and Stanford in 2021. He has been serving as Director of the Science and R&D Division at the Linac Coherent Light Source (LCLS) until 2026, when he became the third Director of the Stanford PULSE Institute. Matthias' research interests include ultrafast x-ray science, petahertz electronics, nanophotonics, and laser physics.
Academic Appointments
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Professor, Photon Science Directorate
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Member, Bio-X
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Principal Investigator, Stanford PULSE Institute
Administrative Appointments
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Director, Stanford PULSE Institute (2026 - Present)
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Professor of Photon Science & Applied Physics (by courtesy), Stanford University (2021 - Present)
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Director, Science and R&D Division, LCLS, SLAC (2021 - 2026)
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Max Planck Fellow, Max Planck Institute of Quantum Optics, Germany (2019 - 2023)
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Professor of Physics, LMU Munich, Germany (2013 - 2021)
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Assistant Professor of Physics, Kansas-State University (2009 - 2013)
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Max Planck Group Leader, Max Planck Institute of Quantum Optics, Germany (2007 - 2013)
Honors & Awards
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Oppenheimer Fellow, DOE National Laboratories (2025)
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OPTICA Fellow, OPTICA (2024)
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APS Fellow, American Physical Society (2019)
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Max Planck Fellow, Max Planck Society (2019)
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ERC Starting Grant, European Research Council (2013)
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Early Career Award, Department of Energy (2012)
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Heisenberg Fellow, German Research Foundation (2012)
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Nernst-Haber Bodenstein Prize, German Bunsen Society (2012)
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Roentgen Prize, Giessen University (2011)
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Emmy-Noether Fellow, German Research Foundation (2007)
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Marie-Curie Fellow, European Research Council (2004)
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Feodor-Lynen Fellow, Alexander von Humboldt foundation (2003)
Professional Education
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Ph.D., University of Goettingen, Germany, Physical Chemistry (2002)
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Certificate, Jena University, Germany, Laser Physics (2000)
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Diploma, University of Goettingen, Germany, Physics (1998)
Current Research and Scholarly Interests
The fastest timescale of electron motion within nanostructures is attoseconds (1 attosecond = 10-18 seconds). We have pioneered the field attosecond nanophotonics and are currently conducting research to extend the state-of-the-art to multi-dimensional spectroscopies, x-ray emission and scattering using intense attosecond XFEL pulses. We aim to explore the dynamics of many-electron effects, including correlation-driven and collective effects. A particularly important open question is the transition from many-body quantum physics to classical dynamics. This will largely impact applications of nanosystems in optoelectronic devices used in ultrafast electronics and computing. As an example, ultrafast plasmonic circuitry can overcome current limitations in resistive electronics and might open an avenue towards quantum computing at ambient temperature.
We also address the question, how aerosolized particles can enable and catalyze light-induced chemical processes. Reaction nanoscopy is a powerful method that is developed in our group for analyzing the surface chemistry on aerosols with nanometer spatial and femtosecond temporal resolution. We aim to advance this technique to solve fundamental questions in astro- and atmospheric chemistry. Among these are the mechanisms of chemical transformations under extreme conditions, where such particles are exposed to high-intensity or high-energy radiation.
We aim to develop, expand, and exploit field-resolved spectroscopies towards higher frequencies in the THz and PHz domains. Opening up these frequency ranges will enable sensitivity to a manyfold of vibrational and electronic transitions in organic electronics and 2D-materials. Field-resolved spectroscopy is a powerful technique that permits addressing the sub-cycle response of a solid to a lightfield. Exploring and controlling many-body excitations and scattering dynamics opens a path for optimized energy conversion in optoelectronic devices. The sub-cycle control of a device builds the basis for lightwave electronics, which may push the speed of computing to its ultimate limit.
We engage in the development of high-average and high-peak power ultrashort light sources. These include optical-parametric chirped pulse amplifiers (OPCPAs) driven by high-power fiber, thin-disk and Innoslab amplifiers. We focus on ultrashort few-cycle pulse generation in the visible and mid-infared spectral region with stable and controllable electric field waveforms. The R&D efforts also include nonlinear tools for pulse characterization. Such capabilities are instrumental in addition to the facility-based light sources in our research on ultrafast nanophotonics, lightwave electronics, and ultrafast x-ray science.
2025-26 Courses
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Independent Studies (6)
- Curricular Practical Training
PHYSICS 291 (Sum) - Directed Studies in Applied Physics
APPPHYS 290 (Aut, Win, Spr, Sum) - Master's Research
CME 291 (Spr) - Research
PHYSICS 490 (Aut, Win, Spr, Sum) - Research and Special Advanced Work
CHEM 200 (Win, Spr, Sum) - Research in Chemistry
CHEM 301 (Win)
- Curricular Practical Training
- Prior Year Courses
Stanford Advisees
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Doctoral Dissertation Reader (AC)
Aaron Ghrist -
Postdoctoral Faculty Sponsor
Jonah Adelman, Chance Ornelas-Skarin -
Doctoral Dissertation Advisor (AC)
Harrison Pasquinilli, Samuel Sahel-Schackis, Selene She, Kazuki Tayama, Shao Ci Wu -
Doctoral (Program)
Sean O'Tool
All Publications
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Trihydrogen Formation on Gold Nanoparticles in Strong Laser Fields.
Nano letters
2026
Abstract
The trihydrogen cation (H3+) plays a central role in proton-transfer chemistry, astrochemical pathways, and hydrogen plasma environments, acting as a key indicator of ultrafast proton rearrangement. Although H3+ formation has been studied extensively in the gas phase, its surface-mediated generation and its sensitivity to nanoparticle morphology remain largely unexplored. Gold nanoparticles (AuNPs), which can localize surface charge and sustain strong electric fields, offer an ideal platform to probe such nonequilibrium reaction pathways. Using reaction nanoscopy, we spatially map H3+ production on AuNPs exposed to intense femtosecond laser fields. By comparing spherical and faceted nanoparticles, we demonstrate how morphology modulates the charge density and governs the reaction efficiency. We find that sharp features on faceted particles concentrate charge more effectively, promoting molecular fragmentation and enabling proton rearrangement and migration that enhance H3+ yields. This work opens new directions for exploiting strong-field interactions at metal interfaces to drive nanoscale reactivity and photocatalysis.
View details for DOI 10.1021/acs.nanolett.5c03438
View details for PubMedID 41592788
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Imaging Valence Electron Rearrangement in a Chemical Reaction Using Hard X-Ray Scattering.
Physical review letters
2025; 135 (8): 083001
Abstract
We have observed the signatures of valence electron rearrangement in photoexcited ammonia using ultrafast hard x-ray scattering. Time-resolved x-ray scattering is a powerful tool for imaging structural dynamics in molecules because of the strong scattering from the core electrons localized near each nucleus. Such core-electron contributions generally dominate the differential scattering signal, masking any signatures of rearrangement in the chemically important valence electrons. Ammonia represents an exception to the typically high core-to-valence electron ratio. We measured 9.8 keV x-ray scattering from gas-phase deuterated ammonia following photoexcitation via a 200 nm pump pulse to the 3s Rydberg state. We observed changes in the recorded scattering patterns due to the initial photoexcitation and subsequent deuterium dissociation. Ab initio calculations confirm that the observed signal is sensitive to the rearrangement of the single photoexcited valence electron as well as the interplay between adiabatic and nonadiabatic dissociation channels. The use of ultrafast hard x-ray scattering to image the structural rearrangement of single valence electrons constitutes an important advance in tracking valence electronic structure in photoexcited atoms and molecules.
View details for DOI 10.1103/53h3-vykl
View details for PubMedID 40929341
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Imaging Valence Electron Rearrangement in a Chemical Reaction Using Hard X-Ray Scattering
PHYSICAL REVIEW LETTERS
2025; 135 (8)
View details for DOI 10.1103/53h3-vykl
View details for Web of Science ID 001556197000003
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Characterizing few-cycle UV resonant dispersive waves through direct field sampling
OPTICS LETTERS
2025; 50 (16): 4962-4965
Abstract
We demonstrate compression of few-cycle ultraviolet (UV) resonant dispersive waves (RDWs) generated in a cascaded hollow capillary fiber setup using a Yb laser system. Temporal characterization is performed using both tunneling ionization with a perturbation for the time-domain observation of an electric field (TIPTOE) and self-diffraction frequency-resolved optical gating (SD-FROG), which show good agreement. Through careful dispersion management, we compress the RDW pulse to 6.9 fs at a ∼390-nm central wavelength. This is the first, to our knowledge, measurement of an RDW using the TIPTOE method and demonstrates the viability of this technique to reliably characterize few-cycle UV pulses with μJ pulse energies.
View details for DOI 10.1364/OL.566906
View details for Web of Science ID 001651959800002
View details for PubMedID 40815715
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Multi-millijoule hollow-core fiber compression of short-wave infrared pulses to a single cycle
OPTICS EXPRESS
2025; 33 (13): 28071-28080
View details for DOI 10.1364/OE.564364
View details for Web of Science ID 001530307300005
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Light field-controlled PHz currents in intrinsic metals.
Science advances
2025; 11 (26): eadv5406
Abstract
Oriented electric currents in metals are routinely driven by applying an external electric potential. Although the response of electrons to the external electric fields occurs within attoseconds, conventional electronics do not use this speed potential. Ultrashort laser pulses with controlled shapes of electric fields that switch direction at petahertz frequencies open perspectives for driving currents in metals. Light field-driven currents were demonstrated in various media including dielectrics, semiconductors, and topological insulators. Now, our research question is whether we can drive and control orders of magnitude more charge carriers in metals enabling ultrafast switching with practically low-energy, picojoule-level pulses. Here, we demonstrate the interaction of light with nanometer-thick metallic layers, which leads to a generation of light field-controlled electric currents. We show that the implantation of metallic layers into a dielectric matrix leads to up to 40 times increase of the sensitivity in contrast to a bare dielectric, decreasing the intensity threshold for lightwave electronics.
View details for DOI 10.1126/sciadv.adv5406
View details for PubMedID 40561038
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Attosecond inner-shell lasing at ångström wavelengths.
Nature
2025
Abstract
Since the invention of the laser, nonlinear effects such as filamentation1, Rabi cycling2,3 and collective emission4 have been explored in the optical regime, leading to a wide range of scientific and industrial applications5-8. X-ray free-electron lasers (XFELs) have extended many optical techniques to X-rays for their advantages of ångström-scale spatial resolution and elemental specificity9. An example is XFEL-driven inner-shell Kα1 (2p3/2 → 1s1/2) X-ray lasing in elements ranging from neon to copper, which has been used for nonlinear spectroscopy and development of new X-ray laser sources10-16. Here we show that strong lasing effects similar to those in the optical regime can occur at 1.5-2.1 Å wavelengths during high-intensity (>1019 W cm-2) XFEL-driven Kα1 lasing of copper and manganese. Depending on the temporal XFEL pump pulse substructure, the resulting X-ray pulses (about 106-108 photons) can exhibit strong spatial inhomogeneities and spectral splitting, inhomogeneities and broadening. Three-dimensional Maxwell-Bloch calculations17 show that the observed spatial inhomogeneities result from X-ray filamentation and that the broad spectral features are driven by sub-femtosecond Rabi cycling. Our simulations indicate that these X-ray pulses can have pulse lengths of less than 100 attoseconds and coherence properties that provide opportunities for quantum X-ray optics applications.
View details for DOI 10.1038/s41586-025-09105-9
View details for PubMedID 40500439
View details for PubMedCentralID 6007888
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Stable high-energy proton acceleration with water-leaf targets driven by intense laser pulses
PHYSICAL REVIEW RESEARCH
2025; 7 (2)
View details for DOI 10.1103/PhysRevResearch.7.023190
View details for Web of Science ID 001501421000010
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Imaging the photochemistry of cyclobutanone using ultrafast electron diffraction: Experimental results.
The Journal of chemical physics
2025; 162 (18)
Abstract
We investigated the ultrafast structural dynamics of cyclobutanone following photoexcitation at λ = 200 nm using gas-phase megaelectronvolt ultrafast electron diffraction. Our investigation complements the simulation studies of the same process within this special issue. It provides information about both electronic state population and structural dynamics through well-separable inelastic and elastic electron scattering signatures. We observe the depopulation of the photoexcited S2 state of cyclobutanone with n3s Rydberg character through its inelastic electron scattering signature with a time constant of (0.29 ± 0.2) ps toward the S1 state. The S1 state population undergoes ring-opening via a Norrish Type-I reaction, likely while passing through a conical intersection with S0. The corresponding structural changes can be tracked by elastic electron scattering signatures. These changes appear with a delay of (0.14 ± 0.05) ps with respect to the initial photoexcitation, which is less than the S2 depopulation time constant. This behavior provides evidence for the ballistic nature of the ring-opening once the S1 state is reached. The resulting biradical species react further within (1.2 ± 0.2) ps via two rival fragmentation channels yielding ketene and ethylene, or propene and carbon monoxide. Our study showcases the value of both gas-phase ultrafast diffraction studies as an experimental benchmark for nonadiabatic dynamics simulation methods and the limits in the interpretation of such experimental data without comparison with such simulations.
View details for DOI 10.1063/5.0266559
View details for PubMedID 40353440
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Burn parameters affect PAH emissions at conditions relevant for prescribed fires
ATMOSPHERIC POLLUTION RESEARCH
2025; 16 (5)
View details for DOI 10.1016/j.apr.2025.102438
View details for Web of Science ID 001428691500001
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Attosecond XUV laser triggers smallest, shortest dance of electrons ever recorded
LASER FOCUS WORLD
2025; 61 (4): 14-17
View details for Web of Science ID 001513076300005
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Generation of fast photoelectrons in strong-field emission from metal nanoparticles
NANOPHOTONICS
2025
View details for DOI 10.1515/nanoph-2024-0719
View details for Web of Science ID 001458864100001
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Generation of fast photoelectrons in strong-field emission from metal nanoparticles.
Nanophotonics (Berlin, Germany)
2025; 14 (9): 1355-1364
Abstract
We investigated the generation and control of fast photoelectrons (PEs) by exposing plasmonic nanoparticles (NPs) to short infrared (IR) laser pulses with peak intensities between 1012 and 3 × 1013 W/cm2. Our measured and numerically simulated PE momentum distributions demonstrate the extent to which PE yields and cutoff energies are controlled by the NP size, material, and laser peak intensity. For strong-field photoemission from spherical silver, gold, and platinum NPs with diameters between 10 and 100 nm our results confirm and surpass extremely high PEs cutoff energies, up to several hundred times the incident laser-pulse ponderomotive energy, found recently for gold nanospheres [Saydanzad et al., Nanophotonics 12, 1931 (2023)]. As reported previously for dielectric NPs [Rupp et al., J. Mod. Opt. 64, 995 (2017)], at higher intensities the cutoff energies we deduce from measured and simulated PE spectra tend to converge to a metal-independent limit. We expect these characteristics of light-induced electron emission from prototypical plasmonic metallic nanospheres to promote the understanding of the electronic dynamics in more complex plasmonic nanostructures and the design of nanoscale light-controlled plasmonic electron sources for photoelectronic devices of applied interest.
View details for DOI 10.1515/nanoph-2024-0719
View details for PubMedID 40309428
View details for PubMedCentralID PMC12038575
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Ionization effects in single-shot carrier-envelope phase detection with gas-gap devices
APPLIED PHYSICS LETTERS
2025; 126 (13)
View details for DOI 10.1063/5.0246794
View details for Web of Science ID 001461487000001
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Correlation-driven attosecond photoemission delay in the plasmonic excitation of C60 fullerene.
Science advances
2025; 11 (7): eads0494
Abstract
Extreme light confinement in plasmonic nanosystems enables novel applications in photonics, sensor technology, energy harvesting, biology, and quantum information processing. Fullerenes represent an extreme case for nanoplasmonics: They are subnanometer carbon-based molecules showing high-energy and ultrabroad plasmon resonances; however, the fundamental mechanisms driving the plasmonic response and the corresponding collective electron dynamics are still elusive. Here, we uncover the dominant role of electron correlations in the dynamics of the giant plasmon resonance (GPR) of the subnanometer system C60 by using attosecond photoemission chronoscopy. We find a characteristic photoemission delay of up to about 300 attoseconds that is purely induced by coherent large-scale electron correlations in the plasmonic potential. These results provide insights into the nature of the plasmon resonances in subnanometer systems and open perspectives for advancing nanoplasmonic applications.
View details for DOI 10.1126/sciadv.ads0494
View details for PubMedID 39937918
View details for PubMedCentralID PMC11818021
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Probing Electronic Coherence between Core-Level Vacancies at Different Atomic Sites
PHYSICAL REVIEW X
2025; 15: 011008
View details for DOI 10.1103/PhysRevX.15.011008
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Roadmap on basic research needs for laser technology
JOURNAL OF OPTICS
2025; 27 (1)
View details for DOI 10.1088/2040-8986/ad8458
View details for Web of Science ID 001377000300001
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Petahertz electronics
NATURE REVIEWS PHYSICS
2024
View details for DOI 10.1038/s42254-024-00764-7
View details for Web of Science ID 001325763200001
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Catalysis in Extreme Field Environments: A Case Study of Strongly Ionized SiO2Nanoparticle Surfaces.
Journal of the American Chemical Society
2024
Abstract
High electric fields can significantly alter catalytic environments and the resultant chemical processes. Such fields arise naturally in biological systems but can also be artificially induced through localized nanoscale excitations. Recently, strong field excitation of dielectric nanoparticles has emerged as an avenue for studying catalysis in highly ionized environments, producing extreme electric fields. While the dynamics of laser-driven surface ion emission has been extensively explored, understanding the molecular dynamics leading to fragmentation has remained elusive. Here, we employ a multiscale approach performing nonadiabatic quantum molecular dynamics (NAQMD) simulations on hydrogenated silica surfaces in both bare and wetted environments under field conditions mimicking those of an ionized nanoparticle. Our findings indicate that hole localization drives fragmentation dynamics, leading to surface silanol dissociation within 50 fs and charge transfer-induced water splitting in wetted environments within 150 fs. Further insight into such ultrafast mechanisms is critical for the advancement of catalysis on the surface of charged nanosystems.
View details for DOI 10.1021/jacs.4c08550
View details for PubMedID 39327984
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Tracking surface charge dynamics on single nanoparticles.
Science advances
2024; 10 (32): eadp1890
Abstract
Surface charges play a fundamental role in physics and chemistry, in particular in shaping the catalytic properties of nanomaterials. However, tracking nanoscale surface charge dynamics remains challenging due to the involved length and time scales. Here, we demonstrate time-resolved access to the nanoscale charge dynamics on dielectric nanoparticles using reaction nanoscopy. We present a four-dimensional visualization of the spatiotemporal evolution of the charge density on individual SiO2 nanoparticles under strong-field irradiation with femtosecond-nanometer resolution. The initially localized surface charges exhibit a biexponential redistribution over time. Our findings reveal the influence of surface charges on surface molecular bonding through quantum dynamical simulations. We performed semi-classical simulations to uncover the roles of diffusion and charge loss in the surface charge redistribution process. Understanding nanoscale surface charge dynamics and its influence on chemical bonding on a single-nanoparticle level unlocks an increased ability to address global needs in renewable energy and advanced health care.
View details for DOI 10.1126/sciadv.adp1890
View details for PubMedID 39110806
View details for PubMedCentralID PMC11305382
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Attosecond delays in X-ray molecular ionization.
Nature
2024; 632 (8026): 762-767
Abstract
The photoelectric effect is not truly instantaneous but exhibits attosecond delays that can reveal complex molecular dynamics1-7. Sub-femtosecond-duration light pulses provide the requisite tools to resolve the dynamics of photoionization8-12. Accordingly, the past decade has produced a large volume of work on photoionization delays following single-photon absorption of an extreme ultraviolet photon. However, the measurement of time-resolved core-level photoionization remained out of reach. The required X-ray photon energies needed for core-level photoionization were not available with attosecond tabletop sources. Here we report measurements of the X-ray photoemission delay of core-level electrons, with unexpectedly large delays, ranging up to 700 as in NO near the oxygen K-shell threshold. These measurements exploit attosecond soft X-ray pulses from a free-electron laser to scan across the entire region near the K-shell threshold. Furthermore, we find that the delay spectrum is richly modulated, suggesting several contributions, including transient trapping of the photoelectron owing to shape resonances, collisions with the Auger-Meitner electron that is emitted in the rapid non-radiative relaxation of the molecule and multi-electron scattering effects. The results demonstrate how X-ray attosecond experiments, supported by comprehensive theoretical modelling, can unravel the complex correlated dynamics of core-level photoionization.
View details for DOI 10.1038/s41586-024-07771-9
View details for PubMedID 39169246
View details for PubMedCentralID 7399650
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Waveform retrieval for ultrafast applications based on convolutional neural networks
APL MACHINE LEARNING
2024; 2 (2)
View details for DOI 10.1063/5.0173933
View details for Web of Science ID 001492056600010
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Terawatt-scale attosecond X-ray pulses from a cascaded superradiant free-electron laser
NATURE PHOTONICS
2024
View details for DOI 10.1038/s41566-024-01427-w
View details for Web of Science ID 001220935700001
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Light-wave-controlled Haldane model in monolayer hexagonal boron nitride.
Nature
2024
Abstract
In recent years, the stacking and twisting of atom-thin structures with matching crystal symmetry has provided a unique way to create new superlattice structures in which new properties emerge1,2. In parallel, control over the temporal characteristics of strong light fields has allowed researchers to manipulate coherent electron transport in such atom-thin structures on sublaser-cycle timescales3,4. Here we demonstrate a tailored light-wave-driven analogue to twisted layer stacking. Tailoring the spatial symmetry of the light waveform to that of the lattice of a hexagonal boron nitride monolayer and then twisting this waveform result in optical control of time-reversal symmetry breaking5 and the realization of the topological Haldane model6 in a laser-dressed two-dimensional insulating crystal. Further, the parameters of the effective Haldane-type Hamiltonian can be controlled by rotating the light waveform, thus enabling ultrafast switching between band structure configurations and allowing unprecedented control over the magnitude, location and curvature of the bandgap. This results in an asymmetric population between complementary quantum valleys that leads to a measurable valley Hall current7, which can be detected by optical harmonic polarimetry. The universality and robustness of our scheme paves the way to valley-selective bandgap engineering on the fly and unlocks the possibility of creating few-femtosecond switches with quantum degrees of freedom.
View details for DOI 10.1038/s41586-024-07244-z
View details for PubMedID 38622268
View details for PubMedCentralID 6205603
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Experimental demonstration of attosecond pump-probe spectroscopy with an X-ray free-electron laser
NATURE PHOTONICS
2024
View details for DOI 10.1038/s41566-024-01419-w
View details for Web of Science ID 001200371400001
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Far-Field Petahertz Sampling of Plasmonic Fields.
Nano letters
2024
Abstract
The response of metal nanostructures to optical excitation leads to localized surface plasmon (LSP) generation with nanoscale field confinement driving applications in, for example, quantum optics and nanophotonics. Field sampling in the terahertz domain has had a tremendous impact on the ability to trace such collective excitations. Here, we extend such capabilities and introduce direct sampling of LSPs in a more relevant petahertz domain. The method allows to measure the LSP field in arbitrary nanostructures with subcycle precision. We demonstrate the technique for colloidal nanoparticles and compare the results to finite-difference time-domain calculations, which show that the build-up and dephasing of the plasmonic excitation can be resolved. Furthermore, we observe a reshaping of the spectral phase of the few-cycle pulse, and we demonstrate ad-hoc pulse shaping by tailoring the plasmonic sample. The methodology can be extended to single nanosystems and applied in exploring subcycle, attosecond phenomena.
View details for DOI 10.1021/acs.nanolett.4c00658
View details for PubMedID 38530705
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Sensitivity Enhancement in Photoconductive Light Field Sampling
ADVANCED OPTICAL MATERIALS
2024
View details for DOI 10.1002/adom.202302490
View details for Web of Science ID 001179163100001
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Propagation effects in polarization-gated attosecond soft-X-ray pulse generation.
Optics express
2024; 32 (2): 1151-1160
Abstract
Accurate estimation of the duration of soft-x-ray pulses from high-harmonic generation (HHG) remains challenging given their higher photon energies and broad spectral bandwidth. The carrier-envelope-phase (CEP) dependence of generated soft-x-ray spectra is indicative of attosecond pulse generation, but advanced simulations are needed to infer the pulse duration from such data. Here, we employ macroscopic propagation simulations to reproduce experimental polarization-gated CEP-dependent soft-x-ray spectra. The simulations indicate chirped pulses, which we theoretically find to be compressible in hydrogen plasmas, suggesting this as a viable compression scheme for broadband soft-x-rays from HHG.
View details for DOI 10.1364/OE.504636
View details for PubMedID 38297673
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From Ultrafast Light-Induced Currents to Spatially-Resolved Field Sampling
edited by Chini, M., Argenti, L., Fang, L.
SPRINGER INTERNATIONAL PUBLISHING AG. 2024: 177-186
View details for DOI 10.1007/978-3-031-47938-0_17
View details for Web of Science ID 001260658600017
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49 W carrier-envelope-phase-stable few-cycle 2.1 & mu;m OPCPA at 10 kHz
OPTICS EXPRESS
2023; 31 (15): 24821-24834
Abstract
We demonstrate a mid-infrared optical parametric chirped pulse amplifier (OPCPA), delivering 2.1 µm center wavelength pulses with 20 fs duration and 4.9 mJ energy at 10 kHz repetition rate. This self-seeded system is based on a kW-class Yb:YAG thin-disk amplifier driving a CEP stable short-wavelength-infrared (SWIR) generation and three consecutive OPCPA stages. Our SWIR source achieves an average power of 49 W, while still maintaining excellent phase and average power stability with sub-100 mrad carrier-envelope-phase-noise and 0.8% average power fluctuations. These parameters enable the OPCPA setup to drive attosecond pump probe spectroscopy experiments with photon energies in the water window.
View details for DOI 10.1364/OE.493326
View details for Web of Science ID 001044920400002
View details for PubMedID 37475300
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Resonance Effect in Brunel Harmonic Generation in Thin Film Organic Semiconductors
ADVANCED OPTICAL MATERIALS
2023
View details for DOI 10.1002/adom.202203070
View details for Web of Science ID 000991603700001
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Enhanced cutoff energies for direct and rescattered strong-field photoelectron emission of plasmonic nanoparticles.
Nanophotonics (Berlin, Germany)
2023; 12 (10): 1931-1942
Abstract
The efficient generation, accurate detection, and detailed physical tracking of energetic electrons are of applied interest for high harmonics generation, electron-impact spectroscopy, and femtosecond time-resolved scanning tunneling microscopy. We here investigate the generation of photoelectrons (PEs) by exposing plasmonic nanostructures to intense laser pulses in the infrared (IR) spectral regime and analyze the sensitivity of PE spectra to competing elementary interactions for direct and rescattered photoemission pathways. Specifically, we measured and numerically simulated emitted PE momentum distributions from prototypical spherical gold nanoparticles (NPs) with diameters between 5 and 70 nm generated by short laser pulses with peak intensities of 8.0 × 1012 and 1.2 × 1013 W/cm2, demonstrating the shaping of PE spectra by the Coulomb repulsion between PEs, accumulating residual charges on the NP, and induced plasmonic electric fields. Compared to well-understood rescattering PE cutoff energies for strong-field photoemission from gaseous atomic targets (10× the ponderomotive energy), our measured and simulated PE spectra reveal a dramatic cutoff-energy increase of two orders of magnitude with a significantly higher contribution from direct photoemission. Our findings indicate that direct PEs reach up to 93 % of the rescattered electron cutoff energy, in contrast to 20 % for gaseous atoms, suggesting a novel scheme for the development of compact tunable tabletop electron sources.
View details for DOI 10.1515/nanoph-2023-0120
View details for PubMedID 39635144
View details for PubMedCentralID PMC11501197
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Reaction nanoscopy of ion emission from sub-wavelength propanediol droplets.
Nanophotonics (Berlin, Germany)
2023; 12 (10): 1823-1831
Abstract
Droplets provide unique opportunities for the investigation of laser-induced surface chemistry. Chemical reactions on the surface of charged droplets are ubiquitous in nature and can provide critical insight into more efficient processes for industrial chemical production. Here, we demonstrate the application of the reaction nanoscopy technique to strong-field ionized nanodroplets of propanediol (PDO). The technique's sensitivity to the near-field around the droplet allows for the in-situ characterization of the average droplet size and charge. The use of ultrashort laser pulses enables control of the amount of surface charge by the laser intensity. Moreover, we demonstrate the surface chemical sensitivity of reaction nanoscopy by comparing droplets of the isomers 1,2-PDO and 1,3-PDO in their ion emission and fragmentation channels. Referencing the ion yields to gas-phase data, we find an enhanced production of methyl cations from droplets of the 1,2-PDO isomer. Density functional theory simulations support that this enhancement is due to the alignment of 1,2-PDO molecules on the surface. The results pave the way towards spatio-temporal observations of charge dynamics and surface reactions on droplets.
View details for DOI 10.1515/nanoph-2022-0714
View details for PubMedID 39635141
View details for PubMedCentralID PMC11501279
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Enhanced cutoff energies for direct and rescattered strong-field photoelectron emission of plasmonic nanoparticles
NANOPHOTONICS
2023
View details for DOI 10.1515/nanoph-2023-0120
View details for Web of Science ID 000969260000001
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Reaction nanoscopy of ion emission from sub-wavelength propanediol droplets
NANOPHOTONICS
2023
View details for DOI 10.1515/nanoph-2022-0714
View details for Web of Science ID 000964452600001
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Linear and Nonlinear Optical Properties of Iridium Nanoparticles Grown via Atomic Layer Deposition
COATINGS
2023; 13 (4)
View details for DOI 10.3390/coatings13040787
View details for Web of Science ID 000977104500001
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Light-Induced Subnanometric Modulation of a Single-Molecule Electron Source.
Physical review letters
2023; 130 (10): 106204
Abstract
Single-molecule electron sources of fullerenes driven via constant electric fields, approximately 1nm in size, produce peculiar emission patterns, such as a cross or a two-leaf pattern. By illuminating the electron sources with femtosecond light pulses, we discovered that largely modulated emission patterns appeared from single molecules. Our simulations revealed that emission patterns, which have been an intractable question for over seven decades, represent single-molecule molecular orbitals. Furthermore, the observed modulations originated from variations of single-molecule molecular orbitals, practically achieving the subnanometric optical modulation of an electron source.
View details for DOI 10.1103/PhysRevLett.130.106204
View details for PubMedID 36962055
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Ion microscopy with evolutionary-algorithm-based autofocusing
ENGINEERING RESEARCH EXPRESS
2023; 5 (1)
View details for DOI 10.1088/2631-8695/acb419
View details for Web of Science ID 000971730900001
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Broadband Photoconductive Sampling in Gallium Phosphide
ADVANCED OPTICAL MATERIALS
2023
View details for DOI 10.1002/adom.202202994
View details for Web of Science ID 000939665800001
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Ultrafast quantum dynamics driven by the strong space-charge field of a relativistic electron beam
OPTICA
2023; 10 (1): 1-10
View details for DOI 10.1364/OPTICA.471773
View details for Web of Science ID 000927471100001
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Strong-field physics with nanospheres
ADVANCES IN PHYSICS-X
2022; 7 (1)
View details for DOI 10.1080/23746149.2021.2010595
View details for Web of Science ID 000784409000001
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Relaxation dynamics in excited helium nanodroplets probed with high resolution, time-resolved photoelectron spectroscopy
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
2022: 28844-28852
Abstract
Superfluid helium nanodroplets are often considered as transparent and chemically inert nanometer-sized cryo-matrices for high-resolution or time-resolved spectroscopy of embedded molecules and clusters. On the other hand, when the helium nanodroplets are resonantly excited with XUV radiation, a multitude of ultrafast processes are initiated, such as relaxation into metastable states, formation of nanoscopic bubbles or excimers, and autoionization channels generating low-energy free electrons. Here, we discuss the full spectrum of ultrafast relaxation processes observed when helium nanodroplets are electronically excited. In particular, we perform an in-depth study of the relaxation dynamics occurring in the lowest 1s2s and 1s2p droplet bands using high resolution, time-resolved photoelectron spectroscopy. The simplified excitation scheme and improved resolution allow us to identify the relaxation into metastable triplet and excimer states even when exciting below the droplets' autoionization threshold, unobserved in previous studies.
View details for DOI 10.1039/d2cp03335f
View details for Web of Science ID 000890034400001
View details for PubMedID 36422471
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Strong-Field Control of Plasmonic Properties in Core-Shell Nanoparticles
ACS PHOTONICS
2022
View details for DOI 10.1021/acsphotonics.2c00663
View details for Web of Science ID 000878995500001
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Complementary dispersive mirror pair produced in one coating run based on desired non-uniformity
OPTICS EXPRESS
2022; 30 (18): 32074-32083
View details for DOI 10.1364/OE.467664
View details for Web of Science ID 000850229100045
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Spatiotemporal sampling of near-petahertz vortex fields
OPTICA
2022; 9 (7): 755-761
View details for DOI 10.1364/OPTICA.459612
View details for Web of Science ID 000822022700013
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Imaging elliptically polarized infrared near-fields on nanoparticles by strong-field dissociation of functional surface groups
EUROPEAN PHYSICAL JOURNAL D
2022; 76 (6)
View details for DOI 10.1140/epjd/s10053-022-00430-6
View details for Web of Science ID 000817283600001
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All-optical nanoscopic spatial control of molecular reaction yields on nanoparticles
OPTICA
2022; 9 (5): 551-560
View details for DOI 10.1364/OPTICA.453915
View details for Web of Science ID 000799613700015
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Fifth-order nonlinear optical response of Alq(3) thin films
RESULTS IN PHYSICS
2022; 37
View details for DOI 10.1016/j.rinp.2022.105513
View details for Web of Science ID 000798985800008
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Few-femtosecond resolved imaging of laser-driven nanoplasma expansion
NEW JOURNAL OF PHYSICS
2022; 24 (4)
View details for DOI 10.1088/1367-2630/ac5e86
View details for Web of Science ID 000783683900001
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Electro-optic characterization of synthesized infrared-visible light fields
NATURE COMMUNICATIONS
2022; 13 (1): 1111
Abstract
The measurement and control of light field oscillations enable the study of ultrafast phenomena on sub-cycle time scales. Electro-optic sampling (EOS) is a powerful field characterization approach, in terms of both sensitivity and dynamic range, but it has not reached beyond infrared frequencies. Here, we show the synthesis of a sub-cycle infrared-visible pulse and subsequent complete electric field characterization using EOS. The sampled bandwidth spans from 700 nm to 2700 nm (428 to 110 THz). Tailored electric-field waveforms are generated with a two-channel field synthesizer in the infrared-visible range, with a full-width at half-maximum duration as short as 3.8 fs at a central wavelength of 1.7 µm (176 THz). EOS detection of the complete bandwidth of these waveforms extends it into the visible spectral range. To demonstrate the power of our approach, we use the sub-cycle transients to inject carriers in a thin quartz sample for nonlinear photoconductive field sampling with sub-femtosecond resolution.
View details for DOI 10.1038/s41467-022-28699-6
View details for Web of Science ID 000763605200010
View details for PubMedID 35236857
View details for PubMedCentralID PMC8891359
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The emergence of macroscopic currents in photoconductive sampling of optical fields.
Nature communications
2022; 13 (1): 962
Abstract
Photoconductive field sampling enables petahertz-domain optoelectronic applications that advance our understanding of light-matter interaction. Despite the growing importance of ultrafast photoconductive measurements, a rigorous model for connecting the microscopic electron dynamics to the macroscopic external signal is lacking. This has caused conflicting interpretations about the origin of macroscopic currents. Here, we present systematic experimental studies on the signal formation in gas-phase photoconductive sampling. Our theoretical model, based on the Ramo-Shockley-theorem, overcomes the previously introduced artificial separation into dipole and current contributions. Extensive numerical particle-in-cell-type simulations permit a quantitative comparison with experimental results and help to identify the roles of electron-neutral scattering and mean-field charge interactions. The results show that the heuristic models utilized so far are valid only in a limited range and are affected by macroscopic effects. Our approach can aid in the design of more sensitive and more efficient photoconductive devices.
View details for DOI 10.1038/s41467-022-28412-7
View details for PubMedID 35181662
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Attosecond coherent electron motion in Auger-Meitner decay.
Science (New York, N.Y.)
1800: eabj2096
Abstract
[Figure: see text].
View details for DOI 10.1126/science.abj2096
View details for PubMedID 34990213
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Efficient nonlinear compression of a thin-disk oscillator to 8.5 fs at 55 W average power
OPTICS LETTERS
2021; 46 (21): 5304-5307
Abstract
We demonstrate an efficient hybrid-scheme for nonlinear pulse compression of high-power thin-disk oscillator pulses to the sub-10 fs regime. The output of a home-built, 16 MHz, 84 W, 220 fs Yb:YAG thin-disk oscillator at 1030 nm is first compressed to 17 fs in two nonlinear multipass cells. In a third stage, based on multiple thin sapphire plates, further compression to 8.5 fs with 55 W output power and an overall optical efficiency of 65% is achieved. Ultrabroadband mid-infrared pulses covering the spectral range 2.4-8µm were generated from these compressed pulses by intra-pulse difference frequency generation.
View details for DOI 10.1364/OL.440303
View details for Web of Science ID 000713723300004
View details for PubMedID 34724461
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Onset of charge interaction in strong-field photoemission from nanometric needle tips
NANOPHOTONICS
2021; 10 (14): 3769-3775
View details for DOI 10.1515/nanoph-2021-0276
View details for Web of Science ID 000712886600020
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Petahertz-scale nonlinear photoconductive sampling in air
OPTICA
2021; 8 (5): 586-590
View details for DOI 10.1364/OPTICA.411434
View details for Web of Science ID 000654252200002
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Saturating multiple ionization in intense mid-infrared laser fields
NEW JOURNAL OF PHYSICS
2021; 23 (5)
View details for DOI 10.1088/1367-2630/abf583
View details for Web of Science ID 000655602600001
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Observation of the quantum shift of a backward rescattering caustic by carrier-envelope phase mapping
PHYSICAL REVIEW A
2021; 103 (4)
View details for DOI 10.1103/PhysRevA.103.043121
View details for Web of Science ID 000646168300006
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Single-shot dispersion sampling for optical pulse reconstruction
OPTICS EXPRESS
2021; 29 (8): 11845-11853
Abstract
We present a novel approach to single-shot characterization of the spectral phase of broadband laser pulses. Our method is inexpensive, insensitive to alignment and combines the simplicity and robustness of the dispersion scan technique, that does not require spatio-temporal pulse overlap, with the advantages of single-shot pulse characterization methods such as single-shot frequency-resolved optical gating at a real-time reconstruction rate of several Hz.
View details for DOI 10.1364/OE.420602
View details for Web of Science ID 000640033600041
View details for PubMedID 33984957
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Mark Stockman: Evangelist for Plasmonics
ACS PHOTONICS
2021; 8 (3): 683-698
View details for DOI 10.1021/acsphotonics.1c00299
View details for Web of Science ID 000630366900001
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Femtosecond Laser Induced Resonant Tunneling in an Individual Quantum Dot Attached to a Nanotip
ACS PHOTONICS
2021; 8 (2): 505-511
View details for DOI 10.1021/acsphotonics.0c01490
View details for Web of Science ID 000621063700017
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Ionization-Induced Subcycle Metallization of Nanoparticles in Few-Cycle Pulses
ACS PHOTONICS
2020; 7 (11): 3207-3215
View details for DOI 10.1021/acsphotonics.0c01282
View details for Web of Science ID 000592916800030
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Femtosecond streaking in ambient air
OPTICA
2020; 7 (10): 1372-1376
View details for DOI 10.1364/OPTICA.398846
View details for Web of Science ID 000581027000021
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Near-Field Induced Reaction Yields from Nanoparticle Clusters
ACS PHOTONICS
2020; 7 (7): 1885-1892
View details for DOI 10.1021/acsphotonics.0c00823
View details for Web of Science ID 000551497000036
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Suppression of individual peaks in two-colour high harmonic generation
JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS
2020; 53 (13)
View details for DOI 10.1088/1361-6455/ab859c
View details for Web of Science ID 000541824100001
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Photoelectron spectroscopy of large water clusters ionized by an XUV comb
JOURNAL OF PHYSICS-PHOTONICS
2020; 2 (3)
View details for DOI 10.1088/2515-7647/ab92b1
View details for Web of Science ID 000572940700001
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High-contrast, intense single-cycle pulses from an all thin-solid-plate setup
OPTICS LETTERS
2020; 45 (2): 367-370
View details for DOI 10.1364/OL.382592
View details for Web of Science ID 000510865100028
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Tunable isolated attosecond X-ray pulses with gigawatt peak power from a free-electron laser
NATURE PHOTONICS
2020; 14 (1): 30-+
View details for DOI 10.1038/s41566-019-0549-5
View details for Web of Science ID 000504727600007
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Carrier-envelope-phase-controlled molecular dissociation by ultrashort chirped laser pulses
PHYSICAL REVIEW A
2019; 100 (6)
View details for DOI 10.1103/PhysRevA.100.063409
View details for Web of Science ID 000501341900009
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Attosecond transient absorption spooktroscopy: a ghost imaging approach to ultrafast absorption spectroscopy.
Physical chemistry chemical physics : PCCP
2019
Abstract
The recent demonstration of isolated attosecond pulses from an X-ray free-electron laser (XFEL) opens the possibility for probing ultrafast electron dynamics at X-ray wavelengths. An established experimental method for probing ultrafast dynamics is X-ray transient absorption spectroscopy, where the X-ray absorption spectrum is measured by scanning the central photon energy and recording the resultant photoproducts. The spectral bandwidth inherent to attosecond pulses is wide compared to the resonant features typically probed, which generally precludes the application of this technique in the attosecond regime. In this paper we propose and demonstrate a new technique to conduct transient absorption spectroscopy with broad bandwidth attosecond pulses with the aid of ghost imaging, recovering sub-bandwidth resolution in photoproduct-based absorption measurements.
View details for DOI 10.1039/c9cp03951a
View details for PubMedID 31793561
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Interplay of pulse duration, peak intensity, and particle size in laser-driven electron emission from silica nanospheres
OPTICS EXPRESS
2019; 27 (19): 27124-27135
Abstract
We present the results of a systematic study of photoelectron emission from isolated dielectric nanoparticles (SiO2) irradiated by intense 25 fs, 780 nm linearly polarized laser pulses as a function of particle size (20 nm to 750 nm in diameter) and laser intensity. We also introduce an experimental technique to reduce the effects of focal volume averaging. The highest photoelectron energies show a strong size dependence, increasing by a factor of six over the range of particles sizes studied at a fixed intensity. For smaller particle sizes (up to 200 nm), our findings agree well with earlier results obtained with few-cycle, ∼4 fs pulses. For large nanoparticles, which exhibit stronger near-field localization due to field-propagation effects, we observe the emission of much more energetic electrons, reaching energies up to ∼200 times the ponderomotive energy. This strong deviation in maximum photoelectron energy is attributed to the increase in ionization and charge interaction for many-cycle pulses at similar intensities.
View details for DOI 10.1364/OE.27.027124
View details for Web of Science ID 000486373100069
View details for PubMedID 31674579
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All-optical spatio-temporal control of electron emission from SiO<sub>2</sub> nanospheres with femtosecond two-color laser fields
NEW JOURNAL OF PHYSICS
2019; 21
View details for DOI 10.1088/1367-2630/ab26c1
View details for Web of Science ID 000476861000004
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Sub-cycle dynamics in relativistic nanoplasma acceleration
SCIENTIFIC REPORTS
2019; 9: 7321
Abstract
The interaction of light with nanometer-sized solids provides the means of focusing optical radiation to sub-wavelength spatial scales with associated electric field enhancements offering new opportunities for multifaceted applications. We utilize collective effects in nanoplasmas with sub-two-cycle light pulses of extreme intensity to extend the waveform-dependent electron acceleration regime into the relativistic realm, by using 106 times higher intensity than previous works to date. Through irradiation of nanometric tungsten needles, we obtain multi-MeV energy electron bunches, whose energy and direction can be steered by the combined effect of the induced near-field and the laser field. We identified a two-step mechanism for the electron acceleration: (i) ejection within a sub-half-optical-cycle into the near-field from the target at >TVm-1 acceleration fields, and (ii) subsequent acceleration in vacuum by the intense laser field. Our observations raise the prospect of isolating and controlling relativistic attosecond electron bunches, and pave the way for next generation electron and photon sources.
View details for DOI 10.1038/s41598-019-43635-3
View details for Web of Science ID 000467709100063
View details for PubMedID 31086214
View details for PubMedCentralID PMC6513988
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Generation and Characterization of Attosecond Pulses from an X-ray Free-electron Laser
IEEE. 2019
View details for Web of Science ID 000482226301273
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Phase- and intensity-resolved measurements of above threshold ionization by few-cycle pulses
JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS
2018; 51 (13)
View details for DOI 10.1088/1361-6455/aac584
View details for Web of Science ID 000434975400003
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Roadmap on plasmonics
JOURNAL OF OPTICS
2018; 20 (4)
View details for DOI 10.1088/2040-8986/aaa114
View details for Web of Science ID 000447428100001
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Attosecond streaking metrology with isolated nanotargets
JOURNAL OF OPTICS
2018; 20 (2)
View details for DOI 10.1088/2040-8986/aa9b08
View details for Web of Science ID 000419338900002
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Single-shot carrier-envelope-phase tagging using an <i>f</i>-2<i>f</i> interferometer and a phase meter: a comparison
JOURNAL OF OPTICS
2017; 19 (12)
View details for DOI 10.1088/2040-8986/aa9865
View details for Web of Science ID 000425217800001
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Signatures and mechanisms of plasmon-enhanced electron emission from clusters in few-cycle laser fields
JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS
2017; 50 (22)
View details for DOI 10.1088/1361-6455/aa900c
View details for Web of Science ID 000414025000001
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Optical Control of Young's Type Double-slit Interferometer for Laser-induced Electron Emission from a Nano-tip
SCIENTIFIC REPORTS
2017; 7: 12661
Abstract
Interference experiments with electrons in a vacuum can illuminate both the quantum and the nanoscale nature of the underlying physics. An interference experiment requires two coherent waves, which can be generated by splitting a single coherent wave using a double slit. If the slit-edge separation is larger than the coherence width at the slit, no interference appears. Here we employed variations in surface barrier at the apex of a tungsten nano-tip as slits and achieved an optically controlled double slit, where the separation and opening-and-closing of the two slits can be controlled by respectively adjusting the intensity and polarization of ultrashort laser pulses. Using this technique, we have demonstrated interference between two electron waves emitted from the tip apex, where interference has never been observed prior to this technique because of the large slit-edge separation. Our findings pave the way towards simple time-resolved electron holography on e.g. molecular adsorbates employing just a nano-tip and a screen.
View details for DOI 10.1038/s41598-017-12832-3
View details for Web of Science ID 000412161000015
View details for PubMedID 28978914
View details for PubMedCentralID PMC5627254
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Non-sequential double ionization with near-single cycle laser pulses
SCIENTIFIC REPORTS
2017; 7: 7488
Abstract
A three-dimensional semiclassical model is used to study double ionization of Ar when driven by a near-infrared and near-single-cycle laser pulse for intensities ranging from 0.85 × 1014 W/cm2 to 5 × 1014 W/cm2. Asymmetry parameters, distributions of the sum of the two electron momentum components along the direction of the polarization of the laser field and correlated electron momenta are computed as a function of the intensity and of the carrier envelope phase. A very good agreement is found with recently obtained results in kinematically complete experiments employing near-single-cycle laser pulses. Moreover, the contribution of the direct and delayed pathways of double ionization is investigated for the above observables. Finally, an experimentally obtained anti-correlation momentum pattern at higher intensities is reproduced with the three-dimensional semiclassical model and shown to be due to a transition from strong to soft recollisions with increasing intensity.
View details for DOI 10.1038/s41598-017-07635-5
View details for Web of Science ID 000407179800006
View details for PubMedID 28790410
View details for PubMedCentralID PMC5548909
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Attosecond physics at the nanoscale
REPORTS ON PROGRESS IN PHYSICS
2017; 80 (5): 054401
Abstract
Recently two emerging areas of research, attosecond and nanoscale physics, have started to come together. Attosecond physics deals with phenomena occurring when ultrashort laser pulses, with duration on the femto- and sub-femtosecond time scales, interact with atoms, molecules or solids. The laser-induced electron dynamics occurs natively on a timescale down to a few hundred or even tens of attoseconds (1 attosecond = 1 as = 10-18 s), which is comparable with the optical field. For comparison, the revolution of an electron on a 1s orbital of a hydrogen atom is ∼152 as. On the other hand, the second branch involves the manipulation and engineering of mesoscopic systems, such as solids, metals and dielectrics, with nanometric precision. Although nano-engineering is a vast and well-established research field on its own, the merger with intense laser physics is relatively recent. In this report on progress we present a comprehensive experimental and theoretical overview of physics that takes place when short and intense laser pulses interact with nanosystems, such as metallic and dielectric nanostructures. In particular we elucidate how the spatially inhomogeneous laser induced fields at a nanometer scale modify the laser-driven electron dynamics. Consequently, this has important impact on pivotal processes such as above-threshold ionization and high-order harmonic generation. The deep understanding of the coupled dynamics between these spatially inhomogeneous fields and matter configures a promising way to new avenues of research and applications. Thanks to the maturity that attosecond physics has reached, together with the tremendous advance in material engineering and manipulation techniques, the age of atto-nanophysics has begun, but it is in the initial stage. We present thus some of the open questions, challenges and prospects for experimental confirmation of theoretical predictions, as well as experiments aimed at characterizing the induced fields and the unique electron dynamics initiated by them with high temporal and spatial resolution.
View details for DOI 10.1088/1361-6633/aa574e
View details for Web of Science ID 000397121600001
View details for PubMedID 28059773
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Phase- and intensity-dependence of ultrafast dynamics in hydrocarbon molecules in few-cycle laser fields
MOLECULAR PHYSICS
2017; 115 (15-16): 1835-1845
View details for DOI 10.1080/00268976.2017.1288935
View details for Web of Science ID 000406645600013
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Delayed electron emission in strong-field driven tunnelling from a metallic nanotip in the multi-electron regime
SCIENTIFIC REPORTS
2016; 6: 35877
Abstract
Illuminating a nano-sized metallic tip with ultrashort laser pulses leads to the emission of electrons due to multiphoton excitations. As optical fields become stronger, tunnelling emission directly from the Fermi level becomes prevalent. This can generate coherent electron waves in vacuum leading to a variety of attosecond phenomena. Working at high emission currents where multi-electron effects are significant, we were able to characterize the transition from one regime to the other. Specifically, we found that the onset of laser-driven tunnelling emission is heralded by the appearance of a peculiar delayed emission channel. In this channel, the electrons emitted via laser-driven tunnelling emission are driven back into the metal, and some of the electrons reappear in the vacuum with some delay time after undergoing inelastic scattering and cascading processes inside the metal. Our understanding of these processes gives insights on attosecond tunnelling emission from solids and should prove useful in designing new types of pulsed electron sources.
View details for DOI 10.1038/srep35877
View details for Web of Science ID 000386762400001
View details for PubMedID 27786287
View details for PubMedCentralID PMC5082369
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Carrier-envelope phase dependence of the directional fragmentation and hydrogen migration in toluene in few-cycle laser fields
AMER INST PHYSICS. 2016: 043206
Abstract
The dissociative ionization of toluene initiated by a few-cycle laser pulse as a function of the carrier envelope phase (CEP) is investigated using single-shot velocity map imaging. Several ionic fragments, CH3 (+), H2 (+), and H3 (+), originating from multiply charged toluene ions present a CEP-dependent directional emission. The formation of H2 (+) and H3 (+) involves breaking C-H bonds and forming new bonds between the hydrogen atoms within the transient structure of the multiply charged precursor. We observe appreciable intensity-dependent CEP-offsets. The experimental data are interpreted with a mechanism that involves laser-induced coupling of vibrational states, which has been found to play a role in the CEP-control of molecular processes in hydrocarbon molecules, and appears to be of general importance for such complex molecules.
View details for DOI 10.1063/1.4941601
View details for Web of Science ID 000383880700008
View details for PubMedID 26958589
View details for PubMedCentralID PMC4760969
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Alignment-assisted field-free orientation of rotationally cold CO molecules (vol 90, 013419, 2014)
PHYSICAL REVIEW A
2016; 93 (3)
View details for DOI 10.1103/PhysRevA.93.039903
View details for Web of Science ID 000371724100015
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Visualization of bond rearrangements in acetylene using near single-cycle laser pulses
FARADAY DISCUSSIONS
2016; 194: 495-508
Abstract
The migration of hydrogen atoms resulting in the isomerization of hydrocarbons is an important process which can occur on ultrafast timescales. Here, we visualize the light-induced hydrogen migration of acetylene to vinylidene in an ionic state using two synchronized 4 fs intense laser pulses. The first pulse induces hydrogen migration, and the second is used for monitoring transient structural changes via Coulomb explosion imaging. Varying the time delay between the pulses reveals the migration dynamics with a time constant of 54 ± 4 fs as observed in the H+ + H+ + CC+ channel. Due to the high temporal resolution, vibrational wave-packet motions along the CC- and CH-bonds are observed. Even though a maximum in isomerization yield for kinetic energy releases above 16 eV is measured, we find no indication for a backwards isomerization - in contrast to previous measurements. Here, we propose an alternative explanation for the maximum in isomerization yield, namely the surpassing of the transition state to the vinylidene configuration within the excited dication state.
View details for DOI 10.1039/c6fd00082g
View details for Web of Science ID 000392422200022
View details for PubMedID 27711784
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Single-Cycle Non-Sequential Double Ionization
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS
2015; 21 (5)
View details for DOI 10.1109/JSTQE.2015.2443976
View details for Web of Science ID 000359252900001
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Alignment-assisted field-free orientation of rotationally cold CO molecules
PHYSICAL REVIEW A
2014; 90 (1)
View details for DOI 10.1103/PhysRevA.90.013419
View details for Web of Science ID 000339443200004
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The Interplay of Nuclear and Electron Wavepacket Motion in the Control of Molecular Processes: A Theoretical Perspective
MOLECULAR QUANTUM DYNAMICS: FROM THEORY TO APPLICATIONS
edited by Gatti, F.
2014: 213-248
View details for DOI 10.1007/978-3-642-45290-1_8
View details for Web of Science ID 000337901900009
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Plasmon-Enhanced-Attosecond-Extreme Ultraviolet Source
PHYSICAL REVIEW LETTERS
2013; 110 (22): 223903
Abstract
A compact high repetition rate attosecond light source based on a standard laser oscillator combined with plasmonic enhancement is analyzed. At repetition rates of tens of MHz, we predict focusable pulses with durations of ≲300 as and a spherical wave front at collimation angles ≲5°. Plasmonic mode and guiding of the attosecond radiation determine the beam parameters. The beam is robust with respect to variations of driver pulse focus and duration.
View details for DOI 10.1103/PhysRevLett.110.223903
View details for Web of Science ID 000319807700004
View details for PubMedID 23767726
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Nanoplasmonic near-field synthesis
PHYSICAL REVIEW A
2013; 87 (3)
View details for DOI 10.1103/PhysRevA.87.033816
View details for Web of Science ID 000316318500006
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Ultrafast phenomena on the nanoscale
ANNALEN DER PHYSIK
2013; 525 (1-2): A13-A14
View details for DOI 10.1002/andp.201300709
View details for Web of Science ID 000314918500001
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(Sub-)femtosecond control of molecular reactions <i>via</i> tailoring the electric field of light
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
2013; 15 (24): 9448-9467
Abstract
We review recent progress in the control over chemical reactions by employing tailored electric field waveforms of intense laser pulses. The sub-cycle tailoring of such waveforms permits the control of electron dynamics in molecules on sub-femtosecond timescales. We show that laser-driven electron dynamics in molecules has the potential to control chemical reactions. In the presence of strong fields, electron and nuclear motion are coupled, requiring models beyond the Born-Oppenheimer approximation for their theoretical treatment. Various mechanisms for the lightwave control of molecular reactions are described, and their relevance for the control of diatomic molecular reactions is discussed. Rapid experimental and theoretical progress is currently being made, indicating that attosecond controlled chemistry is within reach.
View details for DOI 10.1039/c3cp50591j
View details for Web of Science ID 000319576500002
View details for PubMedID 23695586
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Attosecond tracing of correlated electron-emission in non-sequential double ionization
NATURE COMMUNICATIONS
2012; 3: 813
Abstract
Despite their broad implications for phenomena such as molecular bonding or chemical reactions, our knowledge of multi-electron dynamics is limited and their theoretical modelling remains a most difficult task. From the experimental side, it is highly desirable to study the dynamical evolution and interaction of the electrons over the relevant timescales, which extend into the attosecond regime. Here we use near-single-cycle laser pulses with well-defined electric field evolution to confine the double ionization of argon atoms to a single laser cycle. The measured two-electron momentum spectra, which substantially differ from spectra recorded in all previous experiments using longer pulses, allow us to trace the correlated emission of the two electrons on sub-femtosecond timescales. The experimental results, which are discussed in terms of a semiclassical model, provide strong constraints for the development of theories and lead us to revise common assumptions about the mechanism that governs double ionization.
View details for DOI 10.1038/ncomms1807
View details for Web of Science ID 000304611400013
View details for PubMedID 22569361
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Attosecond nanoplasmonic streaking of localized fields near metal nanospheres (vol 84, 121406, 2011)
PHYSICAL REVIEW B
2011; 84 (11)
View details for DOI 10.1103/PhysRevB.84.119911
View details for Web of Science ID 000295263600019
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Attosecond nanoplasmonic streaking of localized fields near metal nanospheres
PHYSICAL REVIEW B
2011; 84 (12)
View details for DOI 10.1103/PhysRevB.84.121406
View details for Web of Science ID 000295007500002
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Predicted Ultrafast Dynamic Metallization of Dielectric Nanofilms by Strong Single-Cycle Optical Fields
PHYSICAL REVIEW LETTERS
2011; 107 (8): 086602
Abstract
We predict a dynamic metallization effect where an ultrafast (single-cycle) optical pulse with a ≲1 V/Å field causes plasmonic metal-like behavior of a dielectric film with a few-nm thickness. This manifests itself in plasmonic oscillations of polarization and a significant population of the conduction band evolving on a ~1 fs time scale. These phenomena are due to a combination of both adiabatic (reversible) and diabatic (for practical purposes irreversible) pathways.
View details for DOI 10.1103/PhysRevLett.107.086602
View details for Web of Science ID 000294067500009
View details for PubMedID 21929186
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Attosecond measurement of petahertz plasmonic near-fields
edited by Stockman, M. I.
SPIE-INT SOC OPTICAL ENGINEERING. 2011
View details for DOI 10.1117/12.893551
View details for Web of Science ID 000295962800012
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Metallization of Nanofilms in Strong Adiabatic Electric Fields
PHYSICAL REVIEW LETTERS
2010; 105 (8): 086803
Abstract
We introduce an effect of metallization of dielectric nanofilms by strong, adiabatically varying electric fields. The metallization causes optical properties of a dielectric film to become similar to those of a plasmonic metal (strong absorption and negative permittivity at low optical frequencies). This is a quantum effect, which is exponentially size-dependent, occurring at fields on the order of 0.1 V/Å and pulse durations ranging from ∼1 fs to ∼10 ns for a film thickness of 3-10 nm.
View details for DOI 10.1103/PhysRevLett.105.086803
View details for Web of Science ID 000281018200007
View details for PubMedID 20868124
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Time of flight-photoemission electron microscope for ultrahigh spatiotemporal probing of nanoplasmonic optical fields
IOP PUBLISHING LTD. 2009: 314005
Abstract
Nanoplasmonic excitations as generated by few-cycle laser pulses on metal nanostructures undergo ultrafast dynamics with timescales as short as a few hundred attoseconds (1 as = 10(-18) s). So far, the spatiotemporal dynamics of optical fields localized on the nanoscale (nanoplasmonic field) have been hidden from direct access in the real space and time domain. An approach which combines photoelectron emission microscopy and attosecond streaking spectroscopy and which provides direct and non-invasive access to the nanoplasmonic field with nanometer-scale spatial resolution and temporal resolution of the order of 100 as has been proposed (Stockman et al 2007 Nat. Photon. 1 539). To implement this approach, a time of flight-photoemission electron microscope (TOF-PEEM) with ∼25 nm spatial and ∼50 meV energy resolution, which has the potential to detect a nanoplasmonic field with nanometer spatial and attosecond temporal resolution, has been developed and characterized using a 400 nm/60 ps pulsed diode laser. The first experimental results obtained using this newly developed TOF-PEEM in a two-photon photoemission mode with a polycrystalline Cu sample and an Ag microstructure film show that the yield and the kinetic energy of the emitted photoelectrons are strongly affected by the nanolocalized plasmonic field.
View details for DOI 10.1088/0953-8984/21/31/314005
View details for Web of Science ID 000267880300006
View details for PubMedID 21828566
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Attoscience: An attosecond stopwatch
NATURE PHYSICS
2008; 4 (7): 515-516
View details for DOI 10.1038/nphys1005
View details for Web of Science ID 000257984600005
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Attosecond electron dynamics
ANNUAL REVIEW OF PHYSICAL CHEMISTRY
2008; 59: 463-492
Abstract
We describe the recent emergence of attosecond science, assessing the present state of the art and discussing several recent examples where attosecond electron dynamics has been studied in atomic and molecular systems. After introducing the generation and characterization of attosecond laser pulses, we describe the use of isolated attosecond pulses in a pump-probe experiment revealing the subcycle time dependence of a multiphoton ionization process and an experiment using the interference from a train of attosecond pulses to extract amplitude and phase information for electronic wave functions. We furthermore discuss experiments where ultrashort laser pulses with a reproducible waveform control electron dynamics in the D(2)(+) molecular ion on attosecond timescales. Attosecond science is coming of age and presently is reaching a level of maturity and sophistication that allows detailed investigations of the role of multielectron dynamics in physics and chemistry.
View details for DOI 10.1146/annurev.physchem.59.032607.093532
View details for Web of Science ID 000255723500019
View details for PubMedID 18031218
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Attosecond nanoplasmonic-field microscope
NATURE PHOTONICS
2007; 1 (9): 539-544
View details for DOI 10.1038/nphoton.2007.169
View details for Web of Science ID 000249609100021
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Nature and role of bridged carbonyl intermediates in the ultrafast photoinduced rearrangement of Ru<sub>3</sub>(CO)<sub>12</sub>
ORGANOMETALLICS
2006; 25 (3): 775-784
View details for DOI 10.1021/om050795o
View details for Web of Science ID 000234906900028
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Ultrafast infrared mechanistic studies of the interaction of 1-Hexyne with group 6 hexacarbonyl complexes
ORGANOMETALLICS
2005; 24 (8): 1852-1859
View details for DOI 10.1021/om049101m
View details for Web of Science ID 000228191400012
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Decomposition of tertiary alkoxy radicals
ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE-INTERNATIONAL JOURNAL OF RESEARCH IN PHYSICAL CHEMISTRY & CHEMICAL PHYSICS
2005; 219 (9): 1205-1222
View details for DOI 10.1524/zpch.2005.219.9.1205
View details for Web of Science ID 000232490800002
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Photo-induced decomposition of organic peroxides: Ultrafast formation and decarboxylation of carbonyloxy radicals
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
2004; 6 (24): 5441-5455
View details for DOI 10.1039/b410875b
View details for Web of Science ID 000225573600001
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Decarboxylation of carbonyloxy radicals: a density functional study
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
2003; 5 (18): 3891-3896
View details for DOI 10.1039/b304544g
View details for Web of Science ID 000185740700010
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Watching photoinduced chemistry and molecular energy flow in solution in real time
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
2003; 42 (20): 2226-2246
Abstract
Energized molecules are the essential actors in chemical transformations in solution. As the rearrangement of bonds requires a movement of nuclei, vibrational energy is often the driving force for a reaction. Vibrational energy can be redistributed within the "hot" molecule, or relaxation can occur when molecules interact. Both processes govern the rates, pathways, and quantum yields of chemical transformations in solution. Unfortunately, energy transfer and the breaking, formation, and rearrangement of bonds take place on ultrafast timescales. This Review highlights experimental approaches for the direct, ultrafast measurement of photoinduced femtochemistry and energy flow in solution. In the first part of this Review, we summarize recent experiments on intra- and intermolecular energy transfer. The second part discusses photoinduced decomposition of large organic peroxides, which are used as initiators in free radical polymerization. The mechanisms and timescales of their decarboxylation determine the initial steps of polymerization and the microstructure of the polymer product.
View details for DOI 10.1002/anie.200200541
View details for Web of Science ID 000183334500003
View details for PubMedID 12772152
https://orcid.org/0000-0002-1710-0775