Femtosecond multiphoton ionization of dialkyl carbonate green solvents at 400 nm using photoelectron-photoion coincidence imaging

Abstract

Femtosecond laser based multiphoton ionization experiments have been carried out for the first time on dialkyl carbonate green solvent molecules i.e. dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate (DMC, DEC, EMC). The dissociation products produced consequent to ionization have been studied by detecting electrons and ions in coincidence mode using velocity map imaging technique. Based on detailed comparative analysis of the mass spectra of DMC, DEC and EMC, we propose possible mechanisms involving a combination of direct bond cleavage as well as isomerization and reorganization to generate the final dissociation products. Further, photoelectron kinetic energy release distributions measured in coincidence with various fragment ions correlated with the possible fragmentation pathways and compared for all three molecules offers a validation of the proposed mechanisms. As an offshoot we obtain experimental estimates for the ionization potentials of DEC and EMC which are hitherto unreported.