%0 Electronic Article
%A Mayer, D.
%A Lever, F.
%A Picconi, David
%A Metje, J.
%A Alisauskas, S.
%A Calegari, F.
%A Düsterer, S.
%A Ehlert, C.
%A Feifel, R.
%A Niebuhr, M.
%A Manschwetus, B.
%A Kuhlmann, M.
%A Mazza, T.
%A Robinson, M. S.
%A Squibb, R. J.
%A Trabattoni, A.
%A Wallner, M.
%A Saalfrank, P.
%A Wolf, T. J. A.
%A Gühr, M.
%T Following excited-state chemical shifts in molecular ultrafast x-ray photoelectron spectroscopy
%N arXiv:2102.13431
%M PUBDB-2024-07841
%M arXiv:2102.13431
%D 2021
%X 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.
%F PUB:(DE-HGF)25
%9 Preprint
%$ pmid:35017539
%U https://bib-pubdb1.desy.de/record/619702