Flow-tube studies of vibrational energy transfer in HF(v)+HF, DF(v)+HF, and DF(v)+D2 systems

A medium-pressure (1 Torr), large-diameter (10 cm) flow tube has been used to measure rate coefficients at 298 °K for (a) total relaxation (sum of vibrational–vibrational and vibrational–rotational, translational processes) of HF(v=1, 2, 3, 4, and 5) by HF, (b) relaxation of DF(1, 2, 3, and 4) by HF, and (c) over-all relaxation of DF(v=1, 2, 3, and 4) by D2. The chemically produced vibrationally excited HF or DF species have been studied by monitoring their vibrational–rotational emission in a fast-flow system. The rate coefficient for the relaxation of HF(1) by HF is 5.3×104 sec−1⋅Torr−1. The measured rate coefficients for the deexcitation of HF(v=2, 3, 4, and 5) by HF are 5.3×105, 8.5×105, 8.8×105, and 2.8×105 sec−1⋅Torr−1, respectively. The rate coefficients for the vibrational–rotational, translational deexcitation from the upper vibrational levels of DF(v) by HF are found to have a nonlinear vibrational dependence. The rate coefficient for the relaxation of DF(v=1) by D2 is 1.35×104 sec−1⋅Torr−1.