The time-resolved infrared fluorescence (IRF) technique has been used to study the vibrational deactivation of CO 2 (00 0 1) and N 2 O(00 0 1) by C 6 D 5 CH 3 and C 6 H 5 CD 3 at ambient temperature (295 ( 2 K). The bimolecular deactivation rate constants were found to be (242 ( 17) × 10 3 and (145 ( 5) × 10 3 Torr -1 s -1 , respectively, for the deactivation of CO 2 (00 0 1), and (253 ( 13) × 10 3 and (376 ( 20) × 10 3 Torr -1 s -1 , respectively, for the deactivation of N 2 O(00 0 1). Experimental deactivation probabilities are calculated and compared with our previous data for deactivation of the same two excited molecules by the colliders C 6