The collision-induced [formula omitted] transition

Abstract

The dependences of the Cl 2( D0 u +,v D ,J D → Cl 2( X) g + E0 g +,v E ,J E ) collisional induced transition rate constants on the vibrational v E, v D, rotational J E quantum numbers, energy gaps, and Franck–Condon factors of the combined levels have been studied in the range of v D=1–5. It has been shown that all the observed collisional induced intramolecular transitions (CIIT) are nonresonant and correspond to loss of up to 1100 cm −1 vibrational energy. The u↔g and ΔΩ=0 propensity rules are valid in the Cl 2( D → Cl 2( X) g + ion-pair states ) CIIT. The vibrational and rotational distributions of the E state levels depend on v D number. For v D=3–5 the E state vibrational level corresponding to maximum Franck–Condon factor with the initial one is mainly populated. The E, v E=0,1,2; β1 g, v β =2; and E, v E=0 levels are populated from the D, v D=2 and 1 ones, respectively. The “ ΔJ low” propensity rule is valid in the Cl 2( D0 u +,v D =1–5,J D → Cl 2( X) g + E0 g +,v E =1–5,J E and β1 g ,v β=2,J β) CIIT. Rotational distribution of the v E=0 levels populated from the v D=1, 2 can be described as the Boltzmann one, T=300 K . The nonadiabatic transitions between potential energy surface corresponding to input Cl 2(D)+Cl 2(X) and output Cl 2(E)+Cl 2(X) channels occur in relatively short-lived collision complex, and CIIT rate constant is in the (0.4–3.2)×10 −11 cm 3/ s range.