Identifying Strong-Field Effects in Indirect Photofragmentation Reactions

TL;DR

This paper investigates how strong ultrafast laser fields influence molecular breakup processes, revealing reaction intermediates and energy levels through wavepacket simulations and angular distribution analysis.

Contribution

It introduces a theoretical approach combining wavepacket calculations and angular analysis to identify reaction intermediates and energy levels in strong-field photofragmentation.

Findings

Identification of NaI as a reaction intermediate across field regimes

Extraction of NaI energy levels from interference patterns

Analysis of angular dependencies reveals reaction mechanisms

Abstract

Exploring molecular breakup processes induced by light-matter interactions has both fundamental and practical implications. However, it remains a challenge to elucidate the underlying reaction mechanism in the strong field regime, where the potentials of the reactant are modified dramatically. Here, we perform a theoretical analysis combined with a time-dependent wavepacket calculation to show how a strong ultrafast laser field affects the photofragment products. As an example, we examine the photochemical reaction of breaking up the molecule NaI into the neutral atoms Na and I, which due to inherent nonadiabatic couplings is indirectly formed in a stepwise fashion via the reaction intermediate NaI. By analyzing the angular dependencies of fragment distributions, we are able to identify the reaction intermediate NaI from the weak to the strong field-induced nonadiabatic regimes. Furthermore, the energy levels of NaI can be extracted from the quantum interference patterns of the transient photofragment momentum distribution.