Inelastic cross sections of excited molecules. III. Absolute cross sections for rotational and vibrational transitions in the Na2(B1Πu) state

For pt. II see ibid., vol. 5, 1386, (1972). Collision-induced rotational and vibrational energy transfer in electronically excited sodium molecules has been investigated by laser-induced fluorescence. As collision partners all rare gases were used as well as H 2 , HD, D 2 , N 2 and CH 4 . The measurements were performed in a glass cell at 600 K and at foreign gas pressures less than or equal to 1 Torr. Absolute values of the rotational cross section are given for angular momentum transfer from mod Delta J mod =1 up to mod Delta J mod =6 for various specified levels in the Na 2 (B 1 Pi u ) state with rotational quantum numbers between J'=12 and J'=99. The total cross section for rotational energy transfer is of the order of 100 AA 2 . It is nearly independent of J' and the vibrational quantum number nu '. The total vibrational cross section is about 10 AA 2 or less.