SPIN-ORBIT BRANCHING IN THE PREDISSOCIATION OF THE C-1-PI IN STATE OFHCL AND DCL - A MANIFESTATION OF QUANTUM INTERFERENCE

We report a combined theoretical-experimental investigation of the pre dissociation of HCl subsequent to photoexcitation of the lowest Rydber g state of (1)Pi symmetry (C (1)Pi). Our particular interest is the ch aracterization of the configurational mixing between this state and th e lower, repulsive valence state of (1)Pi symmetry (A (1)Pi). A plausi ble model for the coupling between these two states, which also involv es spin-orbit coupling between the C state and the a (3)Pi(1) and t (3 )Sigma(1)(+) states, leads to predicted spin-orbit branching ratios, f or both HCl and DCl, which agree qualitatively with the results of a n ew experimental investigation, also reported here. The theoretical sim ulation further strongly suggests that the observed predissociation br anching ratios reflect quantum interference effects. (C) 1998 Elsevier Science B.V. All rights reserved.