Molecular movies and geometry reconstruction using Coulomb explosion imaging

Abstract

Coulomb explosion imaging is a technique of imaging the structure of small molecules in the gas phase and their ultrafast dynamics by inducing the rapid ionization and dissociation of the molecule into its constituent atomic fragments. The momentum vectors of the atomic fragments facilitate the retrieval of the molecule's structure, however, few attempts at geometry reconstruction appear in the published literature, whose vague methodology casts serious doubts on the geometry reconstructions that have been performed, and motivating the need for an investigation into the feasibility of geometry reconstruction. We develop a method for the fast and precise reconstruction of triatomic molecular geometries by casting the task as a nonlinear constrained optimization problem. We use this method to investigate the uncertainty in geometry reconstructions as a function of measurement uncertainty as well as the existence and nature of multiple solutions to the geometry reconstruction problem. We map out the conditions under which molecular geometries may be accurately reconstructed and propose a framework for reconstructing geometries, and therefore producing molecular movies using Coulomb explosion imaging.