Temperature dependence of several vibrational relaxation processes in DF–CO2 mixtures

A pulsed DF chemical laser has been used to excite DF molecules to their first vibrational level. Decay of the infrared DF fluorescence was used to calculate the vibrational relaxation times of DF due to collisions with itself at temperatures between 468 and 920°K as well as at room temperature. The high temperature data were obtained in a laser‐induced fluorescence experiment performed behind a reflected shock wave in a shock tube. The relaxation time of DF(1) due to DF collisions was measured and determined to be $\text{0.063± 0.005μ}\sec \mathrm{·\hspace{0.17em}}\mathrm{atm\hspace{0.17em}at}\text{295°}\mathrm{K}$ increasing to $\text{0.36± 0.03μ}\sec \mathrm{·\hspace{0.17em}}\mathrm{atm\hspace{0.17em}at}\text{\hspace{0.17em}900°}\mathrm{K}$ , which was in agreement with previous shock tube measurements. A measurement of the rate for $\mathrm{DF}\text{(1)+}\mathrm{DF}\text{(1)⇄}\mathrm{DF}\text{(0)+}\mathrm{DF}\text{(2)}$ gave a value of $k_{\mathrm{\nu \; \nu }}{\text{=1.96± 0.2× 10}}^{13}\hspace{0.17em}\mathrm{cc}/\mathrm{mole}\mathrm{·\hspace{0.17em}}\mathrm{sec\hspace{0.17em}at}\text{\hspace{0.17em}295°}\mathrm{K}$ . The rate for the reaction $\mathrm{DF}\text{(1)+}{\mathrm{CO}}_2\text{(000)⇄}\mathrm{DF}\text{(0)+}{\mathrm{CO}}_2\text{(001)}$ rate was measured to be $\text{115(μ}\sec \mathrm{·\hspace{0.17em}}{\mathrm{atm}}^{\text{−1}}\hspace{0.17em}\mathrm{at}\text{\hspace{0.17em}295°}\mathrm{K}\hspace{0.17em}\mathrm{decreasing\; to}\text{\hspace{0.17em}32± 3(μ}\sec \mathrm{·\hspace{0.17em}}\mathrm{atm}{)}^{\text{−1}}\hspace{0.17em}\mathrm{at}\text{\hspace{0.17em}720°}\mathrm{K}\mathrm{.\hspace{0.17em}}{\mathrm{Deactivation\; of\; CO}}_2\text{(001)}\mathrm{by\; DF\; was\; measured\; to\; be}\text{\hspace{0.17em}8.0± 0.8\hspace{0.17em}(μ}\sec \mathrm{·\hspace{0.17em}}\mathrm{atm}{)}^{\text{−1}}\hspace{0.17em}\mathrm{at}\text{\hspace{0.17em}470°}\mathrm{K}\hspace{0.17em}\mathrm{and}\text{\hspace{0.17em}18± 2(μ}\sec \mathrm{·\hspace{0.17em}}\mathrm{atm}{)}^{\text{−1}}\hspace{0.17em}\mathrm{at}\text{\hspace{0.17em}295\hspace{0.17em}°}\mathrm{K.\; All\; of\; the\; measured\; rate\; coefficients,\; converted\; to\; units\; of\; cubic\; centimeters/mole}\mathrm{·\hspace{0.17em}}\mathrm{second}$ , decreased roughly as T⁻¹ from their values at room temperature.