Neural Network Based Molecular Structure Retrieval from Coulomb Explosion Imaging Data

TL;DR

This paper introduces a neural network approach to directly infer molecular structures from Coulomb explosion imaging data, enabling automated, molecule-specific structure retrieval crucial for ultrafast chemical reaction studies.

Contribution

It presents a novel neural network-based scheme for inverse structure determination from Coulomb explosion data, achieving high accuracy in simulated polyhalomethane isomers.

Findings

Achieved ~0.1 atomic units error in structure retrieval

Demonstrated effectiveness on simulated data for multiple isomers

Facilitates automated analysis of Coulomb explosion experiments

Abstract

Determining the structure and following the structural evolution of molecules undergoing chemical reactions is one of the key goals of ultrafast molecular physics and chemistry. Recently, Coulomb explosion imaging has emerged as a promising technique for imaging the evolving structure of individual molecules in the gas phase. However, its practical application for structure determination is hampered by the lack of suitable algorithms to directly retrieve the molecular structure from the measured fragment-ion momentum data. Here, we propose a scheme to solve the underlying inverse problem by employing neural networks to infer the initial atomic positions from the final ion momenta on an event-by-event basis. Using this scheme, we retrieve the structure of several polyhalomethane isomers from simulated Coulomb explosion imaging data with an average per-atom position error of approximately 0.1 atomic units, i.e., to within 5% of the typical bond lengths. This development paves the way for an automated structure retrieval from Coulomb explosion data one molecule at a time, making it ideally suitable for analyzing pump-probe experiments where several products are formed that need to be distinguished.