Shock tube study of DF vibrational relaxation

Abstract

The vibrational relaxation of DF behind incident shock waves in the temperature range 800–4000° K has been studied by monitoring the 3.5‐μm infrared emission. Relaxation times reduced to standard pressure were obtained for mixtures containing 1%–10% DF in Ar and for mixtures containing N₂, H₂, and F atoms. These data were used for calculation of the relaxation times of DF due to these various gases. The relaxation data can be summarized by ${\mathrm{P\; \tau }}_{\mathrm{DF–DF}}{\text{=1.4× 10}}^{\text{−3}}\exp {\text{(63.7/T}}^{\text{1/3}}\mathrm{)\; \hspace{0.17em}\mu }\sec ·\mathrm{atm}$ (above 2000°K), ${\mathrm{P\; \tau }}_{\mathrm{DF–Ar}}{\text{=7.1× 10}}^{\text{−3}}\exp {\text{(128.6/T}}^{\text{1/3}}\mathrm{)\hspace{0.17em}\mu }\sec ·\mathrm{atm}{\mathrm{,\hspace{0.17em}P\; \tau }}_{{\mathrm{DF–H}}_2}{\text{=1.9× 10}}^{\text{−2}}\exp {\text{(35/T}}^{\text{1/3}}\mathrm{)\hspace{0.17em}\mu }\sec ·\mathrm{atm}$ . The values of ${\mathrm{P\; \tau }}_{{\mathrm{DF–N}}_2}$ fell between those for Ar and D₂. The deactivation rate of DF by F was measured to be ${\text{1.5× 10}}^{13}\mathrm{cc}/\mathrm{mole}·\sec$ . The measurements were compared to the predictions of several theories of vibration‐to‐translation and vibration‐to‐rotation energy transfer.