HF Vibrational Relaxation by F Atoms

Vibrational relaxation rates of HF in the presence of F atoms have been measured behind incident shock waves in mixtures of SF6, HF, and Ar. The HF emission at 2.7 μ was monitored to infer the rate of HF relaxation. The F-atom concentration was calculated and correlated with the HF relaxation rate. Within the experimental accuracy, the rate coefficient for F-atom relaxation of HF(1) to HF(0) is 3 × 1013cc/mole · sec corresponding to a relaxation time of 0.0059 μ sec·atm at 2000°K. This is approximately 26.5 times more efficient than self-relaxation by HF at 2000°K.