Following excited-state chemical shifts in molecular ultrafast x-ray photoelectron spectroscopy

Mayer, D.; Gühr, M.; Squibb, R. J.; Calegari, F.; Wallner, M.; Düsterer, S.; Niebuhr, M.; Robinson, M. S.; Manschwetus, B.; Metje, J.; Wolf, T. J. A.; Ehlert, C.; Saalfrank, P.; Picconi, David; Mazza, T.; Alisauskas, S.; Kuhlmann, M.; Trabattoni, A.; Lever, F.; Feifel, R.

Preprint

PUBDB-2024-07841

Following excited-state chemical shifts in molecular ultrafast x-ray photoelectron spectroscopy

Mayer, D.Extern*DESY* ; Lever, F. ; Picconi, D. (Corresponding author)Extern* ; Metje, J. ; Alisauskas, S.DESY* ; Calegari, F.DESY* ; Düsterer, S.XFEL.EU*DESY* ; Ehlert, C. ; Feifel, R. ; Niebuhr, M. ; Manschwetus, B. ; Kuhlmann, M. ; Mazza, T. ; Robinson, M. S. ; Squibb, R. J. ; Trabattoni, A. ; Wallner, M. ; Saalfrank, P. ; Wolf, T. J. A.Extern*XFEL.EU* ; Gühr, M.

2021

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Report No.: arXiv:2102.13431

Abstract: The conversion of photon energy into other energetic forms in molecules is accompanied by charge moving on ultrafast timescales. We directly observe the charge motion at a specific site in an electronically excited molecule using time-resolved x-ray photoelectron spectroscopy (TR-XPS). We extend the concept of static chemical shift from conventional XPS by the excited-state chemical shift (ESCS), which is connected to the charge in the framework of a potential model. This allows us to invert TR-XPS spectra to the dynamic charge at a specific atom. We demonstrate the power of TR-XPS by using sulphur 2p-core-electron-emission probing to study the UV-excited dynamics of 2-thiouracil. The new method allows us to discover that a major part of the population relaxes to the molecular ground state within 220-250 fs. In addition, a 250-fs oscillation, visible in the kinetic energy of the TR-XPS, reveals a coherent exchange of population among electronic states.

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