Ion Recoil Following (2+1) REMPI of Nascent Atoms ‐ The Effect on Nascent Velocity Distributions in Velocity Map Imaging

Abstract

AbstractVelocity map imaging has achieved thus far are solution at 1eV kinetic energy release of ∼30 meV, thus 3% ΔE/E. In order to further improve the resolution we need to look more critically at one of the assumptions in the imaging method–that the conversion of neutral fragments to ionic fragments using the standard REMPI technique does not significantly change the nascent velocity distribution of the neutral species. This is shown in this paper to be a questionable assumption in many cases. The effects of ion recoil due to the detection process in the photodissociation of HI and O2 are predicted to fall in the 2–3% range for normal conditions in velocity map imaging. Recoil effects are illustrated for REMPI of D atoms cooled in a supersonic discharge expansion. Dramatic effects of recoil are also illustrated here for the photodissociation of HI. Recoil effects are shown to play a role in the final resolution of many types of velocity mapping experiments.