A dispersed fluorescence and ab initio investigation of the X̃B12 and ÃA12 electronic states of the PH2 molecule

Abstract

In this work, the X̃B12 and ÃA12 electronic states of the phosphino (PH2) free radical have been studied by dispersed fluorescence and ab initio methods. PH2 molecules were produced in a molecular free-jet apparatus by laser vaporizing a silicon rod in the presence of phosphine (PH3) gas diluted in helium. The laser-induced fluorescence, from the excited ÃA12 electronic state down to the ground electronic state, was dispersed and analyzed. Ten (υ1υ2υ3) vibrationally excited levels of the ground electronic state, with υ1⩽2, υ2⩽6, and υ3=0, have been observed. Ab initio potential-energy surfaces for the X̃B12 and ÃA12 electronic states have been calculated at 210 points. These two states correlate with a Πu2 state at linearity and they interact by the Renner-Teller coupling and spin-orbit coupling. Using the ab initio potential-energy surfaces with our RENNER computer program system, the vibronic structure and relative intensities of the ÃA12→X̃B12 emission band system have been calculated in order to corroborate the experimental assignments.