Photodissociation of DCl dimer selected by an electrostatic hexapole field combined with a Doppler-selected time-of-flight technique: observation of [ClDCl] transient species

Abstract

The photodissociation of the DCl dimer, which was preferentially selected from the cluster beam using a hexapole electrostatic field prior to the photolysis, was studied by a Doppler-selected time-of-flight (DS-TOF) technique at 243 nm. We observed the [ClDCl] transient product after deuterium elimination from (DCl)₂. By measuring the dependence of the enhanced signal for the photodissociated D atom on the hexapole voltage, it was found that the DS-TOF spectrum is composed of two kinds of velocity component: one is a fast velocity component which originates from the dimer only, and the other is a slow velocity component which originates not only from the dimer but also from higher DCl cluster sizes. The fast velocity component of the spectrum shows oscillating structures, which may be an indication of the nascent internal (mainly vibrational) state of [ClDCl]. The spacing of the peaks is about 800 cm⁻¹, which is less than half of the normal stretching frequency of the DCl monomer (i.e. 2091 cm⁻¹). Therefore, we tentatively conclude that the present spectrum exhibits strong perturbation by the adjacent Cl atom in the [ClDCl] transient species.