Vibrationally mediated selective excitation of matrix-isolated NO (B 2Π) applied to the study of intramolecular energy redistribution among the excited valence states

Abstract

The B 2Π(ν′) 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 ν=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 2Π (ν′ =0–6) levels. New time and energy resolved data on vibrationally relaxed and unrelaxed emissions from B 2Π(ν′) of 14N 16O and 15N 16O are presented. As previously reported by Chergui et al., the relaxation cascade among the B 2Π, b 4Σ + 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.