VIBRATIONALLY MEDIATED SELECTIVE EXCITATION OF MATRIX-ISOLATED NO(B2-PI) APPLIED TO THE STUDY OF INTRAMOLECULAR ENERGY REDISTRIBUTION AMONG THE EXCITED VALENCE STATES

The B 2-PI(nu') vibronic levels of NO in Ar and Kr matrices are selectively populated by a sequential infrared-visible laser excitation. A significant fraction of the NO molecules are brought into high lying vibrational levels (up to nu=27) of the ground electronic state by IR laser initiated V-V pumping. A second laser operating in the visible range produces an efficient single photon excitation of the B 2-PI (nu'=0-6) levels. New time and energy resolved data on vibrationally relaxed and unrelaxed emissions from B 2-PI (nu') of (NO)-N-14-O-16 and (NO)-N-15-O-16 are presented. As previously reported by Chergui et al., the relaxation cascade among the B 2-PI, b 4-SIGMA-, a 4-PI and A 2-SIGMA+ states is reasonably described in terms of the usual simple model taking into account the coupling between the various electronic states as well as the intramolecular and phonon Franck-Condon factors. The results are consistent with the idea that in solid Ne, Ar and Kr there is no heavy atom effect on the radiationless transitions in NO.