Vibrational Relaxation of O2 in O2−D2 Mixtures and of H2 and D2

Abstract

Shock‐tube interferometry has been used to observe vibrational relaxation of O₂ in O₂+D₂ mixtures. From 300° to 850°K the present shock tube and previous ultrasonic relaxation times in atmosphere seconds are given by ${\log }_{10}{\mathrm{(p\tau }}_{{\mathrm{O}}_2-{\mathrm{D}}_2}{\text{)=27.3T}}^{-\frac{1}{3}}\text{−8.35}$ . Above 1500°K the relaxation time of O₂ is further shortened due to effects of chemical reaction or possibly to a resonant‐energy exchange with the more rapidly excited D₂. Hydrogen vibrational relaxation is too rapid to be resolved, yielding ${\mathrm{p\tau }}_{{\mathrm{H}}_2}{\text{<2×10}}^{\text{−6}}\hspace{0.17em}\mathrm{atm}·\sec$ for T = 1400°K. The vibrational relaxation of deuterium appears to be more complex than other diatoms studied and is not yet understood. However, it is observed that ${\mathrm{p\tau }}_{{\mathrm{D}}_2}{\text{<6×10}}^{\text{−6}}\mathrm{atm}·\sec$ at T = 1400°K.