Ultrafast adsorbate excitation probed with sub-ps resolution XAS
Abstract
We use a pump-probe scheme to measure the time evolution of the C K-edge X-ray absorption spectrum (XAS) from CO/Ru(0001) after excitation by an ultrashort high-intensity optical laser pulse. Due to the short duration of the X-ray probe pulse and precise control of the pulse delay, the excitation-induced dynamics during the first ps after the pump can be resolved with unprecedented time resolution. By comparing with theoretical (DFT) spectrum calculations we find high excitation of the internal stretch and frustrated rotation modes occurring within 200 fs of laser excitation, as well as thermalization of the system in the ps regime. The ~100 fs initial excitation of these CO vibrational modes is not readily rationalized by traditional theories of nonadiabatic coupling of adsorbates to metal surfaces, e. g. electronic frictions based on first order electron-phonon coupling or transient population of adsorbate resonances. We suggest that coupling of the adsorbate to non-thermalized electron-hole pairs is responsible for the ultrafast initial excitation of the modes.
Keywords
Cite
@article{arxiv.2106.03818,
title = {Ultrafast adsorbate excitation probed with sub-ps resolution XAS},
author = {Elias Diesen and Hsin-Yi Wang and Simon Schreck and Matthew Weston and Hirohito Ogasawara and Jerry LaRue and Fivos Perakis and Martina Dell'Angela and Flavio Capotondi and Luca Giannessi and Emanuele Pedersoli and Denys Naumenko and Ivaylo Nikolov and Lorenzo Raimondi and Carlo Spezzani and Martin Beye and Filippo Cavalca and Boyang Liu and Jörgen Gladh and Sergey Koroidov and Piter S. Miedema and Roberto Costantini and Tony F. Heinz and Frank Abild-Pedersen and Johannes Voss and Alan C. Luntz and Anders Nilsson},
journal= {arXiv preprint arXiv:2106.03818},
year = {2022}
}
Comments
16 pages, 16 figures. To be published in Physical Review Letters: https://journals.aps.org/prl/accepted/c1070Y74M8b18063d9cd0221b000631d50ef7a249