Vibrational Relaxation of Nitric Oxide in Argon

Vibrational relaxation times of NO diluted in Ar were measured by monitoring infrared emission of NO at 5.3 μ. Measurements were made in shock waves over the temperature range of 900–2700°K. NO was found to relax exponentially and the relaxation times of NO in NO–NO and NO–Ar collisions were estimated. The results were expressed by $$\log {\mathrm{p\tau }}_{\mathrm{NO–NO}}{\text{\hspace{0.17em}=\hspace{0.17em}6.1T}}^{\text{−1/3}}\text{\hspace{0.17em}−\hspace{0.17em}1.1}\mathrm{atm}\mathrm{·\mu }\sec$$ and $$\log {\mathrm{p\tau }}_{\mathrm{NO–Ar}}{\text{\hspace{0.17em}=\hspace{0.17em}14.7T}}^{\text{−1/3}}\text{\hspace{0.17em}+\hspace{0.17em}0.15}\mathrm{atm}\mathrm{·\mu }\sec$$ .