Time-dependent density functional theory study of strong-field laser-induced coulomb explosion of the HCl dimer

TL;DR

This study uses time-dependent density functional theory to analyze how laser-induced Coulomb explosion of the HCl dimer depends on ionization levels and molecular orientation, revealing distinct fragmentation pathways and their experimental signatures.

Contribution

It provides a detailed, channel-resolved interpretation of Coulomb explosion dynamics, linking ionization, orientation, and fragmentation pathways with experimental observables.

Findings

Higher early-time ionization leads to near-simultaneous four-body breakup.

Sequential and three-body fragmentation are favored at lower ionization levels.

Distinct kinetic energy and emission-angle distributions correspond to different fragmentation channels.

Abstract

We present a channel-resolved interpretation of laser-driven Coulomb explosion of the HCl dimer from an ensemble of trajectories. Three dominant outcomes are identified: a minor three-body channel and two four-body channels (sequential and near-simultaneous dissociation of both molecules). The key result is that pathway selection is strongly correlated with the degree of ionization during the laser interaction, which is in turn strongly modulated by laser-molecule orientation. Higher early-time ionization predisposes the system toward near-simultaneous four-body breakup, whereas lower ionization favors sequential and three-body fragmentation; for low-ionization cases, a fragment-resolved charge metric further differentiates three-body and sequential behavior. These charge-dependent trends consistently map onto experimentally accessible observables: the simultaneous mechanism dominates the high-energy tail of the kinetic energy release (KER) spectrum and populate distinct regions of the emission-angle distributions, while sequential events concentrate at lower KER. Overall, early-time charge evolution provides a unifying explanation for channel branching and for the channel-resolved fragmentation signatures.