Coulomb explosion dynamics of methoxycarbonylsulfenyl chloride by 3D multimass imaging

Abstract

Coupling covariance map analysis with ultrafast laser-induced Coulomb explosion imaging (CEI) enabled us to characterise the dissociative ionisation dynamics of methoxycarbonylsulfenyl chloride (H3COCOSCl). We applied a 3D multi-coincidence detection technique which is necessary for covariance imaging analysis. With the aid of such analysis, we found meaningful correlations between several product ion pairs that revealed different fragmentation channels. A weak, narrow correlation in the covariance image of H3COC(O)+/Cl+ was assigned to a concerted three-body dissociation channel. We also observed a broadly distributed correlation in the covariance image of COS+/HCO+, which is ascribed to a multi-body fragmentation channel. Ab initio calculations were carried out to determine the likely starting structures. A very sharp feature in the covariance image of Cl+/ CH3 + indicated that this pair of ions is produced from a two-body-like fragmentation event of CH3Cl2+. We show by direct comparison with CEI of CH3Cl that, contrary to a previously suggested assignment, this ion pair is produced from CH3Cl, which is formed either in the bubbler or gas line before the molecular beam interacts with the laser beam.