Rate constants for total relaxation from the rotational levels J=7.5, 20.5, 31.5 and 40.5 in NO((XII1/2)-I-2, nu=2) in collisions with He, Ar and N-2: a comparison between experiment and theory

Using the infrared-ultraviolet double resonance (IRUVDR) technique, rate co efficients have been measured for the relaxation of NO( X(2)Pi(1/2), upsilo n = 2, J = 7.5, 20.5 and 31.5) in collisions with He, Ar, N-2 and NO itself . For relaxation from levels J = 31.5 and 40.5, rates were measured by a ne w method in which the IRUVDR method was implemented instantly on NO molecul es formed by photodissociation of NO2 at 355 nm. The rate coefficients for collisions with He, Ar and N-2 are found to decrease at high J, with the de crease least with He. The experimental results for NO-He and NO-Ar are show n to agree well with those from coupled states quantum scattering calculati ons on ab initio potential energy surfaces. (C) 1999 Elsevier Science B.V. All rights reserved.