THE STUDY OF VIBRATIONALLY EXCITED N 2 MOLECULES WITH THE AID OF AN ISOTHERMAL CALORIMETER

Abstract

Vibrationally excited nitrogen molecules produced both by a microwave discharge in nitrogen and also by the reaction[Formula: see text]have been examined using an isothermal calorimetric probe.In the first case the energy associated with an 'active' nitrogen stream, due to vibrationally excited N 2 , was found to be 6.03 kcal mole −1 of total nitrogen. The subsequent relaxation of this species was found to occur almost entirely on the walls of the reaction vessel, with a collision efficiency of 4.5 × 10 −4 . The addition of other gases greatly accelerated the homogeneous relaxation rate. Collisional efficiencies of N 2 O, CO 2 , and Ar were found to be 0.8 × l0 −4 , 2.3 × 10 −5 , and 1.0 × 10 −6 respectively.The vibrationally excited nitrogen produced by the N/NO reaction was found to possess 20 ± 4 kcal mole −1 of energy compared with the maximum of 75 kcal mole −1 allowed by the exothermicity of the reaction.