Desorption Dynamics of Heavy Alkali Metal Atoms (Rb, Cs) off the Surface of Helium Nanodroplets

TL;DR

This study combines experimental ion imaging and density functional theory to investigate how rubidium and cesium atoms detach from helium nanodroplets, revealing effective mass models and electronic relaxation during desorption.

Contribution

It provides a detailed analysis of the desorption dynamics of heavy alkali metals from helium nanodroplets using combined experimental and theoretical approaches, highlighting deviations and electronic state relaxations.

Findings

Desorption dynamics well described by pseudodiatomic model with effective masses ~10 and 13.

Deviations observed for Rb in the 6p state.

Electronic relaxation into low-lying states occurs during desorption.

Abstract

We present a combined ion imaging and density functional theory study of the dynamics of the desorption process of rubidium and cesium atoms off the surface of helium nanodroplets upon excitation of the perturbed $6s$ and $7s$ states, respectively. Both experimental and theoretical results are well represented by the pseudodiatomic model for effective masses of the helium droplet in the desorption reaction of m_eff/m_He~10 (Rb) and 13 (Cs). Deviations from this model are found for Rb excited to the 6p state. Photoelectron spectra indicate that the dopant-droplet interaction induces relaxation into low-lying electronic states of the desorbed atoms in the course of the ejection process.