A5081102607- Laser-Matter Interactions and Applications
- Atomic and Molecular Physics
- Advanced Chemical Physics Studies
- Mass Spectrometry Techniques and Applications
- Advanced X-ray Imaging Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Electron and X-Ray Spectroscopy Techniques
- Laser-Plasma Interactions and Diagnostics
- Spectroscopy and Quantum Chemical Studies
- Ion-surface interactions and analysis
- Vanadium and Halogenation Chemistry
- Catalysis and Oxidation Reactions
- Nuclear physics research studies
- Advanced Electron Microscopy Techniques and Applications
- Laser Design and Applications
- Nuclear Physics and Applications
- Quantum optics and atomic interactions
- Photochemistry and Electron Transfer Studies
- Electrochemical Analysis and Applications
- Laser-induced spectroscopy and plasma
- Photocathodes and Microchannel Plates
Goethe University Frankfurt
2020-2024
Max Planck Institute for Nuclear Physics
2020
Goethe Institute
2020
University of Bonn
1988-1997
Abstract Following structural dynamics in real time is a fundamental goal towards better understanding of chemical reactions. Recording snapshots individual molecules with ultrashort exposure times key ingredient this goal, as atoms move on femtosecond (10 −15 s) timescales. For condensed-phase samples, ultrafast, atomically resolved structure determination has been demonstrated using X-ray and electron diffraction. Pioneering experiments have also started addressing gaseous samples....
Ultrashort x-ray pulses from free-electron lasers can efficiently charge up and trigger the full fragmentation of molecules. By coincident detection to five ions resulting rapid Coulomb explosion highly charged iodomethane, we show that three-dimensional equilibrium geometry this prototypical polyatomic system be determined measured ion momenta with help a buildup model. Supported by simulations how would reflect specific changes in molecular bond lengths angles, demonstrate...
A central motivation for the development of x-ray free-electron lasers has been prospect time-resolved single-molecule imaging with atomic resolution. Here, we show that photoelectron diffraction—where a emitted after absorption illuminates molecular structure from within—can be used to image increase internuclear distance during x-ray-induced fragmentation an O2 molecule. By measuring molecular-frame emission patterns two-photon sequential K-shell ionization in coincidence fragment ions,...
If matter absorbs a photon of sufficient energy it emits an electron. The question the duration emission process has intrigued scientists for decades. With advent attosecond metrology, experiments addressing such ultrashort intervals became possible. While these types studies require experimental precision, we present here novel measurement approach that avoids those difficulties. We instead extract delay from interference pattern generated as emitted photoelectron is diffracted by parent...
We present experimental data on the non-adiabatic strong field ionization of atomic hydrogen using elliptically polarized femtosecond laser pulses at a central wavelength 390 nm. Our measured results are in very good agreement with numerical solution time-dependent Schr\"odinger equation (TDSE). Experiment and TDSE show four above-threshold (ATI) peaks electron's energy spectrum. The most probable emission angle (also known as 'attoclock-offset angle' or 'streaking angle') is found to...
The ultrafast structural dynamics of water following inner-shell ionization is a crucial issue in high-energy radiation chemistry. We have exposed isolated molecules to short x-ray pulse from free-electron laser and detected momenta all produced ions coincidence. By combining experimental results theoretical modeling, we can image dissociation individual unprecedented detail. reveal significant molecular H2O2+, such as asymmetric deformation bond-angle opening, leading two-body or three-body...
We experimentally investigate the effects of linear photon momentum on distributions photoions and photoelectrons generated in one-photon ionization an energy range 300 eV≤Eγ≤40 keV. Our results show that for each event is imparted onto photoion, which essentially system's center mass. Nevertheless, mean value ion distribution along light propagation direction backward-directed by −3/5 times momentum. These confirm a 90-year-old prediction.Received 30 March 2020Revised 5 May 2020Accepted 8...
We report on a multiparticle coincidence experiment performed at the European X-ray Free-Electron Laser Small Quantum Systems instrument using COLTRIMS reaction microscope. By measuring two ions and electrons in coincidence, we investigate double core-hole generation O_{2} molecules gas phase. Single-site two-site core holes have been identified their molecular-frame electron angular distributions obtained for breakup of oxygen molecule into doubly charged ions. The measured are compared to...
The photodissociation dynamics of strong-field ionized methyl iodide were probed using intense extreme ultraviolet (XUV) radiation produced by the SPring-8 Angstrom Compact free electron LAser.
Distant ligands invert photoelectron circular dichroism.
Relative abundances of the various ionic charges resulting from photoionization argon by monochromatized synchrotron radiation at energies between 3150 and 4900 eV have been measured with low statistical error. Despite fact that already, right onset K excitation (3203.5 eV), almost full 1s binding energy is deposited in atom, relative change smoothly over region np up to 6 above limit. While this behaviour, caused Rydberg shake-off (about 0.5 probability 4p resonance) recapture photoelectron...
We present experimental data on the strong-field ionization of argon dimer in a co-rotating two-color laser field. observe subcycle interference pattern photoelectron momentum distribution and infer Wigner time delay using holographic angular streaking electrons. find that varies by more than 400 attoseconds as function electron emission direction with respect to molecular axis. The measured is found be independent parity dimercation good agreement our theoretical model based an aligned...
The differential photoelectron circular dichroism (PECD) of O $1s$ photoelectrons $R$-trifluoromethyloxirane enantiomers as a function the emission direction in molecular frame reference and from which circularly polarized light hits molecule, is studied experimentally theoretically for different kinetic energies. A coincident detection two ionic fragments, performed with cold target recoil ion momentum spectroscopy, allows us to determine orientation molecule laboratory obtain addition...
Abstract We investigate experimentally and theoretically the N 1s photoionization of fixed-in-space 2 molecules at a photon energy 880 eV. In our experiment, we employed circularly polarized synchrotron radiation for coincident electron fragment-ion detection using cold target recoil ion momentum spectroscopy. The accompanying angle-resolved calculations were carried out by multichannel single-center method code within frozen-core Hartree–Fock approximation. computed emission distributions...
Deep core excitation of a small molecule leads to ejection several electrons and dissociation into numerous alternative sets fragment ions. We describe an experiment which identifies complete such arising from decay triatomic molecules (and measures their total charge) via triply coincident detection in time-of-flight mass spectrometer. Careful data correction furthermore enables estimation contributions channels comprising one neutral fragment. OCS were photoexcited by monochromatic x-rays...
Extremely high charge states of atoms and molecules can be created when they are irradiated by intense x-ray pulses. At certain photon energies, electron ejection from drastically enhanced transient resonances during the sequential ionization process. Here we report on observation such resonance effects in a molecule, ${\mathrm{CH}}_{3}\mathrm{I}$, show photon-energy-dependent shift resonance-induced structures ion state distributions. By comparing distribution ${\mathrm{CH}}_{3}\mathrm{I}$...
We report on the strong field ionization of ${\mathrm{H}}_{2}$ by a corotating two-color laser field. measure electron momentum distribution in coincidence with kinetic energy release (KER) dissociating hydrogen molecules. In addition to characteristic half-moon structure, we observe low-energy structure at KER about 3.5 eV. speculate that outgoing interacts molecular ion, despite absence classical recollisions under these conditions. Time-dependent density functional theory simulations...
Abstract When a very strong light field is applied to molecule an electron can be ejected by tunneling. In order quantify the time-resolved dynamics of this ionization process, concept Wigner time delay used. The properties process depend on tunneling direction relative molecular axis. Here, we show experimental and theoretical data for tunnel H 2 molecules demonstrate its dependence emission with respect We find, that observed changes in quantitatively explained elongated/shortened travel...
During the last decade, X-ray free-electron lasers (XFELs) have enabled study of light-matter interaction under extreme conditions. Atoms which are subject to XFEL radiation charged by a complex interplay (several subsequent) photoionization events and electronic decay processes within few femtoseconds. The with molecules is even more intriguing, since intricate nuclear dynamics occur as start dissociate during charge-up process. Here, we demonstrate that analyzing photoelectron angular...
We study strong-field ionization of molecular hydrogen in highly intense corotating two-color laser fields. The measured electron momentum distributions show alternating half rings (AHRs) that are characteristic subcycle interference. report on the role field ratio for visibility this peak electric at 780 nm compared to 390 ${E}_{780}/{E}_{390}$ is varied from 0.037 0.18. find very good agreement with results our semiclassical simulation. conclude AHR pattern visible if two conditions...
We report on strong field ionization of S- and R-propylene oxide in circularly polarized two-color laser fields. find that the relative helicity two single color fields affects photoelectron circular dichroism (PECD). Further, we observe PECD is modulated as a function sub-cycle release time electron. Our experimental observations are successfully described by heuristic model based electrons chiral initial states, which selectively liberated and, after tunneling, interact with an achiral...
We report a fully differential study of ionization the Ne L shell by Compton scattering 20 keV photons. find two physical mechanisms that modify Compton-electron emission. Firstly, we observe electrons at their parent nucleus. Secondly, distinct maximum in electron momentum distribution close-to-zero attribute to focusing Coulomb potential.
We present an experimental and theoretical study of core-level ionization small hetero- homo-nuclear molecules employing circularly polarized light address molecular-frame photoelectron angular distributions in the light's polarization plane (CP-MFPADs). find that main forward-scattering peaks CP-MFPADs are slightly tilted with respect to molecular axis. show this tilt angle can be directly connected bond length by a simple, universal formula. The extraction becomes more accurate as energy...
We study strong field ionization of molecular hydrogen in highly intense co-rotating two-color (CoRTC) laser fields. The measured electron momentum distributions show alternating half-rings (AHR) that are characteristic for sub-cycle interference. report on the role ratio visibility this peak electric at 780 nm compared to 390 $E_{780}/E_{390}$ is varied from 0.037 0.18. find very good agreement with results our semiclassical simulation. conclude AHR pattern visible if two conditions...