Photoacoustic Study of Vibrational Relaxation of NO

The first vibrational level of NO diluted in He is excited by the mechanically chopped CO laser beam and the relaxation rate constant is determined by analysing the phase shift of the acoustic signals at a temperature range of 235 – 294 K. Additional measurements in a shock tube have been done to cover the higher temperature range of 700–1900 K. The present results agree very well with those of previous work. The transition probability of vibrational energy transfer of NO to He can be expressed by

The short-range repulsive collision model is found to represent the present experimental results of the NOHe system.