Simultaneous imaging of vibrational, rotational, and electronic wave packet dynamics in a triatomic molecule

TL;DR

This study demonstrates how combined experimental and computational techniques can simultaneously visualize vibrational, rotational, and electronic wave packet dynamics in sulfur dioxide, revealing complex couplings crucial for understanding molecular reactions.

Contribution

It introduces a method using time-resolved Coulomb explosion imaging and quantum simulations to directly observe coupled molecular motions in polyatomic molecules.

Findings

Direct mapping of bending vibrations in SO2

Influence of molecular alignment on vibrational wave packets

Insights into electronic state coupling due to nuclear motion

Abstract

Light-induced molecular dynamics often involve the excitation of several electronic, vibrational, and rotational states. Since the ensuing electronic and nuclear motion determines the pathways and outcomes of photoinduced reactions, our ability to monitor and understand these dynamics is crucial for molecular physics, physical chemistry, and photobiology. However, characterizing this complex motion represents a significant challenge when different degrees of freedom are strongly coupled. In this Letter, we demonstrate how the interplay between vibrational, rotational, and electronic degrees of freedom governs the evolution of molecular wave packets in the low-lying states of strong-field-ionized sulfur dioxide. Using time-resolved Coulomb explosion imaging (CEI) and quantum mechanical wave packet simulations, we directly map the bending vibrations of the molecule, show how the vibrational wave packet is influenced by molecular alignment, and elucidate the consequences of nuclear motion for the coupling between the two lowest electronic states of the cation. Our results demonstrate that multi-coincident CEI can be an efficient experimental tool for characterizing coupled electronic and nuclear motion in polyatomic molecules.