The observation of chemical reactions on the time scale of the motion of electrons and nuclei has been made possible by lasers with ever shortened pulse lengths. Superfluid helium represents a special solvent that permits the synthesis of novel classes of molecules that have eluded dynamical studies so far. However, photoexcitation inside this quantum solvent triggers a pronounced response of the solvation shell, which is not well understood. Here we present a mechanistic description of the solvent response to photoexcitation of indium (In) dopant atoms inside helium nanodroplets (HeN), obtained from femtosecond pump-probe spectroscopy and time-dependent density functional theory simulations. For the In-HeN system, part of the excited state electronic energy leads to expansion of the solvation shell within 600 fs, initiating a collective shell oscillation with a period of about 30 ps. These coupled electronic and nuclear dynamics will be superimposed on intrinsic photoinduced processes of molecular systems inside helium droplets.
@article{arxiv.1804.04497,
title = {Femtosecond photoexcitation dynamics inside a quantum solvent},
author = {Bernhard Thaler and Sascha Ranftl and Pascal Heim and Stefan Cesnik and Leonhard Treiber and Ralf Meyer and Andreas W. Hauser and Wolfgang E. Ernst and Markus Koch},
journal= {arXiv preprint arXiv:1804.04497},
year = {2018}
}