Exact collinear calculations of the N2 O(X1∑+) → N2(1∑+g) + O(1S) photodissociation process

Abstract

Calculations of transition probabilities and UV (118–136 nm), absorption spectra associated with the process N 2 O(X 1 ∑ + ) hv → N 2 ( 1 ∑ + g ) + O( 1 S) are presented. These are the first collinear calculations of this kind in which no artificial separation between photon absorption and dissociation has been assumed. The N 2 vibrational state distributions and absorption spectra are studied as a function of photon frequency and initial vibrational level of N 2 O. The absorption spectra are found to have single symmetric peak when starting from the (0,0,0) level and to consist of two unequal peaks when starting from the (1,0,0) or (0,0,1) levels. If (0,0,0) is the initial state, we obtain that the N 2 is mainly formed in the ν = 0 state for λ ⪢ 124 nm, while population inversion is predicted to occur in the “blue” wing (λ < 124 nm) of the absorption curve. Assuming the (1,0,0) to be the initial state, we predict the N 2 vibrational state distribution to be inverted at regions (λ < 123 nm) where the absorption probability is quite significant. Starting from the (0,0,1) state we obtain that the N 2 vibrational state distributional is inverted for most photon frequencies in which absorption occurs. The role of VT processes (“interfragment coupling”) in determining, the N 2 vibrational state distributions is also discussed.