Desorption Dynamics of Rb_2 Molecules off the Surface of Helium Nanodroplets

TL;DR

This study investigates how rubidium dimers detach from helium nanodroplets upon laser excitation, revealing that their desorption resembles diatomic dissociation and is influenced mainly by intramolecular dynamics rather than host interactions.

Contribution

It provides new insights into the desorption process of Rb_2 molecules from helium nanodroplets, highlighting the role of intramolecular degrees of freedom over host effects.

Findings

Rb_2 desorption resembles diatomic dissociation.

Ion distributions are governed by Rb_2 intramolecular dynamics.

Pump-probe dynamics are slower for Rb_2^+ than Rb^+.

Abstract

The desorption dynamics of rubidium dimers (Rb_2) off the surface of helium nanodroplets induced by laser excitation is studied employing both nanosecond and femtosecond ion imaging spectroscopy. Similarly to alkali metal atoms, we find that the Rb_2 desorption process resembles the dissociation of a diatomic molecule. However, both angular and energy distributions of detected Rb_2^+ ions appear to be most crucially determined by the Rb_2 intramolecular degrees of freedom rather than by those of the Rb_2He_N complex. The pump-probe dynamics of Rb_2^+ is found to be slower than that of Rb^+ pointing at a weaker effective guest-host repulsion for excited molecules than for single atoms.