Ultrafast charge transfer processes accompanying KLL Auger decay in aqueous KCl solution

TL;DR

This study investigates ultrafast charge transfer during KLL Auger decay in aqueous KCl, revealing charge-dependent differences in spectra and highlighting the role of solvent interactions in charge redistribution.

Contribution

It provides new insights into charge transfer mechanisms during Auger decay in solvated ions, combining experimental spectra with ab initio calculations.

Findings

Strong satellite peak in K$^+$ Auger spectrum linked to electron transfer from water.

No such peak observed for Cl$^-$, indicating charge dependence.

Charge transfer processes influence charge redistribution after core-hole creation.

Abstract

X-ray photoelectron spectroscopy (XPS) and KLL Auger spectra of aqueous KCl solution were measured for the K$^+$ and Cl$^-$ edges. While the XPS spectra of potassium and chloride have similar structures, both exhibiting only weak satellite structures near the main line, the Auger spectra of these isoelectronic ions differ dramatically. A very strong satellite peak was found in the K$^+$ KLL Auger spectrum at the low kinetic energy side of the $^1$D state. Using equivalent core models and ab initio calculations this spectral structure was assigned to electron transfer processes from solvent water molecules to the solvated K$^+$ cation. Contrary to the potassium case, no extra peak was found in the KLL Auger spectrum of solvated Cl$^-$ indicating on a strong dependence of the underlying processes on ionic charge. The observed charge transfer processes are suggested to play an important role in charge redistribution following single and multiple core-hole creation in atomic and molecular systems placed into an environment.