Relative state-to-state cross sections for inelastic collisions between NO X (2) Pi(1/2) (upsilon = 20, J = 0.5, e or f) and He have been determined in a crossed molecular beam setup at a collision energy of 195 cm(-1). Efficient initial state preparation of the NO molecules is achieved by stimulated emission pumping by way of the NO B (2) Pi(1/2) (upsilon = 5) state. The rotational state distribution of the inelastically scattered NO molecules is probed by laser induced fluorescence through the A (2) Sigma(+) (upsilon = 3) state. The measured cross sections are compared with close-coupled quantum scattering calculations on both a recently reported ab initio potential energy surface (PES) and an extension of this PES which takes into account the elongation of the NO bond in upsilon = 20. In the latter calculations, the highly vibrationally excited molecule is treated as a rigid rotor with a bond length equal to the average of the upsilon = 20 level. Even with such an apparently drastic assumption, agreement between the experimental results and the scattering calculations on the latter PES is excellent.
Stefano Coda, Joan Decker, Oleg Krutkin, Umesh Kumar, Jean Arthur Cazabonne
Christophe Marcel Georges Galland, Konstantin Malchow, Wen Chen, Sakthi Priya Amirtharaj