The rate constants for vibrational relaxation of NO+ (v = 1) and NO+ (v = 4
) in collisions with CH4 were measured from thermal to 1 eV center of mass
collisional energy using a selected ion flow drift tube. These experimental
data are interpreted theoretically using the semiclassical (classical path
) approach of Billing and the potential energy surface, constructed on the
basis of the model of Gislason and Ferguson. (C) 1999 Elsevier Science B.V.