The Kinetic Energy of PAH Dication and Trication Dissociation Determined by Recoil-Frame Covariance Map Imaging

TL;DR

This study measures the kinetic energy released during the dissociation of PAH dications and trications using recoil-frame covariance imaging, supported by simulations, revealing energy ranges for different fragmentation channels.

Contribution

It introduces a high-precision method combining recoil-frame covariance imaging and BOMD simulations to analyze PAH ion dissociation energies.

Findings

Dications release 1.94-2.60 eV of kinetic energy.

Trications release 2.95-5.29 eV of kinetic energy.

Method enables detailed energy analysis of PAH fragmentation.

Abstract

We investigated the dissociation of dications and trications of three polycyclic aromatic hydrocarbons (PAHs), fluorene, phenanthrene, and pyrene. PAHs are a family of molecules ubiquitous in space and involved in much of the chemistry of the interstellar medium. In our experiments, ions are formed by interaction with 30.3 nm extreme ultraviolet (XUV) photons, and their velocity map images are recorded using a PImMS2 multi-mass imaging sensor. Application of recoil-frame covariance analysis allows the total kinetic energy release (TKER) associated with multiple fragmentation channels to be determined to high precision, ranging 1.94-2.60 eV and 2.95-5.29 eV for the dications and trications, respectively. Experimental measurements are supported by Born-Oppenheimer molecular dynamics (BOMD) simulations.