Time-resolved studies on the collapse of magnesium atom foam in helium nanodroplets

TL;DR

This study uses femtosecond dual-pulse spectroscopy to investigate the ionization dynamics and collapse behavior of magnesium atom foam in helium nanodroplets, revealing how light influences their stability and ionization pathways.

Contribution

It introduces a novel application of femtosecond dual-pulse spectroscopy to study the collapse and ionization of magnesium foam in helium nanodroplets, providing new insights into their reaction mechanisms.

Findings

Collapse reduces ionization

Pulse intensity ratio controls ionization pathways

Direct probe of foam response at zero delay

Abstract

Magnesium atoms embedded in superfluid helium nanodroplets have been identified to arrange themselves in a metastable network, refered to as foam. In order to investigate the ionization dynamics of this unique structure with respect to a possible light-induced collapse the femtosecond dual-pulse spectroscopy technique is applied. Around zero optical delay a strong feature is obtained which represents a direct probe of the foam response. We found that upon collapse, ionization is reduced. A particlar intensity ratio of the pulses allows to address either direct ionization or photoactivation of the neutral complexes, thus affecting reaction pathways. A simplified excitation scheme visualizes possible scenarios in accordance with the experimental observations.