The influence of x-ray pulse length on space-charge effects in optical pump/x-ray probe photoemission
- Pump-probe photoelectron spectroscopy (PES) is a versatile tool to investigate the dynamics of transient states of excited matter. Vacuum space-charge effects can mask these dynamics and complicate the interpretation of electron spectra. Here we report on space-charge effects in Au 4f photoemission from a polycrystalline gold surface, excited with moderately intense 90 ps (FWHM) soft x-ray probe pulses, under the influence of the Coulomb forces exerted by a pump electron cloud, which was produced by intense 40 fs laser pulses. The experimentally observed kinetic energy shift and spectral broadening of the Au 4f lines, measured with highly-efficient time-of-flight spectroscopy, are in good agreement with simulations utilizing a mean-field model of the electrostatic pump electron potential. This confirms that the line broadening is predominantly caused by variations in the take-off time of the probe electrons without appreciable influence of local scattering events. Our findings might be of general interest for pump-probe PES withPump-probe photoelectron spectroscopy (PES) is a versatile tool to investigate the dynamics of transient states of excited matter. Vacuum space-charge effects can mask these dynamics and complicate the interpretation of electron spectra. Here we report on space-charge effects in Au 4f photoemission from a polycrystalline gold surface, excited with moderately intense 90 ps (FWHM) soft x-ray probe pulses, under the influence of the Coulomb forces exerted by a pump electron cloud, which was produced by intense 40 fs laser pulses. The experimentally observed kinetic energy shift and spectral broadening of the Au 4f lines, measured with highly-efficient time-of-flight spectroscopy, are in good agreement with simulations utilizing a mean-field model of the electrostatic pump electron potential. This confirms that the line broadening is predominantly caused by variations in the take-off time of the probe electrons without appreciable influence of local scattering events. Our findings might be of general interest for pump-probe PES with picosecond-pulse-length sources.…
| Author details: | Danilo KühnGND, Erika Giangrisostomi, Raphael Martin JayORCiDGND, Florian SorgenfreiORCiDGND, Alexander FöhlischORCiDGND |
|---|---|
| DOI: | https://doi.org/10.1088/1367-2630/ab2f5c |
| ISSN: | 1367-2630 |
| Title of parent work (English): | New journal of physics : the open-access journal for physics |
| Publisher: | IOP Publ. Ltd. |
| Place of publishing: | Bristol |
| Publication type: | Article |
| Language: | English |
| Date of first publication: | 2019/07/23 |
| Publication year: | 2019 |
| Release date: | 2020/12/16 |
| Tag: | ARTOF; electron spectroscopy; mean-field model; pump-probe; space-charge effects; x-ray photoemission |
| Volume: | 21 |
| Number of pages: | 12 |
| Funding institution: | FLAG-ERA-Graphene-Basic Research 2 2017 in project LaMeS DFG [400335214]; ERCEuropean Research Council (ERC) [669531] |
| Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie |
| DDC classification: | 5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik |
| Peer review: | Referiert |
| Publishing method: | Open Access / Gold Open-Access |
| DOAJ gelistet | |
| License (English): |  Creative Commons - Namensnennung 3.0 Unported |
