EFFECTS OF ORBITAL ANGULAR-MOMENTUM IN PH2 AND PD2 - RENNER-TELLER AND SPIN-ORBIT-COUPLING

The vibrational and K-type rotational levels of the (X) over tilde(2)B (1) and (A) over tilde(2)A(1) states of PH2 have been fitted by least squares to give a pair of Born-Oppenheimer potential curves for the co mbining electronic states. The effects of the orbital angular-momentum coupling between these states, which are derived from a common (II)-I -2 state of linear PH2, have been considered in detail. The effects ar e manifest in both the behavior of the vibronic origins and the effect ive vibronic spin-orbit coupling constants. We have also calculated th e rotational constants for a range of vibronic states of PH2. Analogou s rotational constants, band origins, and spin-orbit coupling constant s of PD2 have been calculated by use of the potential curves derived f rom the fit to PH2. The agreement between the calculated origins and t hose measured experimentally is quite satisfactory. The vibronic depen dence of the relative transition moments and of the fluorescence lifet imes have also been calculated for both PH2 and PD2.