Direct inner-shell photoionization of Xe atoms embedded in helium nanodroplets

TL;DR

This study measures photoelectron spectra of xenon atoms embedded in helium nanodroplets, revealing ionization dynamics, charge states, and electron transfer processes relevant for advanced spectroscopic techniques.

Contribution

First measurement of photoelectron spectra of Xe atoms in He nanodroplets, highlighting ionization mechanisms and electron transfer effects in this environment.

Findings

Xe ionization exceeds charge transfer ionization in droplets.

Predominant formation of singly charged Xe ions despite Auger decay.

Electron spectra show low-energy features and nearly unshifted Xe lines.

Abstract

We present the first measurements of photoelectron spectra of atomic clusters embedded in superfluid helium (He) nanodroplets. Owing to the large absorption cross section of xenon (Xe) around 100 eV photon energy (4d inner-shell ionization), direct dopant photoionization exceeds charge transfer ionization via the ionized He droplets. Despite the predominant creation of Xe^2+ and Xe^3+ by subsequent Auger decay of free Xe atoms, for Xe embedded in He droplets only singly charged Xe_k^+, k=1,2,3 fragments are observed. Broad Xe^+ ion kinetic-energy distributions indicate Coulomb explosion of the ions due to electron transfer to the primary Auger ions from surrounding neutral atoms. The electron spectra correlated with Xe ions emitted from the He nanodroplets contain a low-energy feature and nearly unshifted Xe photolines. These results pave the way to extreme ultraviolet (XUV) and x-ray photoelectron spectroscopy of clusters and molecular complexes embedded in He nanodroplets.