Spectroscopically resolved resonant interatomic Coulombic decay in photoexcited large He nanodroplets

TL;DR

This study demonstrates that resonant interatomic Coulombic decay (ICD) occurs efficiently in large helium nanodroplets under weak radiation, revealing secondary processes like electron recombination as key mechanisms, and suggests ICD as a diagnostic tool for nanosystem relaxation.

Contribution

It provides new insights into ICD mechanisms in weakly excited helium nanodroplets, highlighting the role of secondary processes and extending understanding beyond intense radiation regimes.

Findings

ICD occurs efficiently at low photon energies in helium nanodroplets.

ICD is observed above ionization threshold due to electron recombination.

ICD can be used to monitor relaxation dynamics in nanosystems.

Abstract

Interatomic Coulombic decay (ICD) processes play a crucial role in weakly bound complexes exposed to intense or high-energy radiation. Using large helium nanodroplets, we demonstrate that ICD is efficient even when the droplets are irradiated by weak synchrotron radiation at relatively low photon energies. Below the ionization threshold, resonant excitation of multiple centers efficiently induces resonant ICD as previously observed for intense pulses [A. C. LaForge et al., PRX 11, 021011 (2021)]. More surprisingly, we observe ICD even above the ionization threshold due to recombination of photoelectrons and ions into excited states which subsequently decay by ICD. This demonstrates the importance of secondary processes, in particular electron scattering and recombination, in inducing ICD in extended condensed phase systems. In addition, we show that ICD can serve as a diagnostic tool for monitoring the relaxation dynamics of highly-excited and ionized weakly-bound nanosystems.