Embedded metal cluster in strong laser fields

TL;DR

This paper investigates the ultrafast dynamics of a metal cluster embedded in a rare gas matrix under strong laser excitation, revealing relaxation stages and the stabilizing effect of the surrounding medium.

Contribution

It provides a detailed mixed quantum-classical simulation of the energy transport and stabilization mechanisms in laser-excited embedded metal clusters.

Findings

Multiple relaxation stages from femtoseconds to picoseconds.

Raregas matrix stabilizes highly charged clusters.

Long-term slow processes observed after initial dynamics.

Abstract

We discuss microscopic mechanisms of the violent dynamics following strong laser excitation of a metal cluster embedded in a rare gas matrix, taking as test case Na$_8$@Ar$_434$. This covers at least two aspects : first, it represents the typical experimental situation of metal clusters handled in raregas matrices or a finite drop of surrounding raregas material, and second, it serves as a generic test case for highly excited chromophores in inert surroundings addressing questions of energy transport and perturbation of the medium. We simulate the process up to 10 ps using a mixed quantum mechanical (for the electrons) and classical (ions and atoms) approach and analyze the emerging dynamics with respect to all basic constituents : cluster electrons, cluster ions, and matrix atoms. We find several stages of relaxation taking place with time scales from a few fs to over a few ps and much slower processes remaining for long after the simulation. A particularly interesting aspect is that the surrounding raregas material stabilizes a highly charged metal cluster which would otherwise explode without delay.