Towards simultaneous imaging of ultrafast nuclear and electronic dynamics in small molecules

TL;DR

This paper introduces a combined imaging method to simultaneously capture ultrafast nuclear and electronic dynamics in small molecules, demonstrated through experimental and numerical studies of H2+ dissociation.

Contribution

It presents a novel approach integrating Coulomb explosion and photoelectron imaging for real-time molecular dynamics visualization.

Findings

Successful experimental measurement of delay-dependent kinetic energy release.

Numerical simulation of transient photoelectron spectra during dissociation.

Validation of the imaging model against the Schrödinger equation results.

Abstract

When a chemical bond is broken, the molecular structure undergoes a transformation. An ideal experiment should probe the change in the electronic and nuclear structure simultaneously. Here, we present a method for the simultaneous time-resolved imaging of nuclear and electron dynamics by combining Coulomb explosion imaging with strong-field photoelectron momentum imaging. The simplest chemical reaction, H$_2^+$ $\rightarrow$ H$^+ +$ H, is probed experimentally for the delay-dependent kinetic energy release, and numerically for the transient change in the photoelectron spectra during the dissociation process. The three-dimensional Schr\"odinger equation is solved in the fixed-nuclei approximation numerically and the results are compared to those from a simple imaging model. The numerical results reflect the evolution in the electron density in the molecular ion as its bond is first stretched and then brakes apart. Our work shows how simple gas-phase chemical dynamics can be captured in complete molecular movies.