Rotational effects in the band oscillator strengths and predissociation linewidths for the lowest 1Π u - X 1∑ +g transitions of N 2

Abstract

A coupled-channel Schrödinger equation (CSE) model of N2 photodissociation, which includes the effects of all interactions between the b, c, and o Πu1 and the C and C′ Πu3 states, is employed to study the effects of rotation on the lowest- ν Πu1 -X 1∑ g+ (ν,0) band oscillator strengths and Πu1 predissociation linewidths. Significant rotational dependences are found which are in excellent agreement with recent experimental results, where comparisons are possible. New extreme-ultraviolet (EUV) photoabsorption spectra of the key b Πu1 ← X 1∑ g+ (3,0) transition of N2 are also presented and analyzed, revealing a b (ν=3) predissociation linewidth peaking near J=11. This behavior can be reproduced only if the triplet structure of the C state is included explicitly in the CSE-model calculations, with a spin-orbit constant A≈15 cm-1 for the diffuse C (ν=9) level which accidentally predissociates b (ν=3). The complex rotational behavior of the b-X (3,0) and other bands may be an important component in the modeling of EUV transmission through nitrogen-rich planetary atmospheres. © 2005 American Institute of Physics.