Vibrational relaxation of DF(v = 1 and 3) in H/sub 2/, D/sub 2/, N/sub 2/, and HF at 200 K

The laser-induced fluorescence technique was used to measure the rate coefficients for the deactivation of DF(v = 1) and DF(v = 3) in H/sub 2/, D/sub 2/, N/sub 2/, and HF at 200 +- 5 K. The rate coefficients for deactivation by H/sub 2/, N/sub 2/, and HF were found to scale with v as v/sup 1.9plus-or-minus0.1/, essentially the same as the scaling at 295 K. The relaxation rates for DF(v = 1) were compared with data obtained at higher temperatures. At 200 K, the exchange probability of HF(1) + H/sub 2/(0) was the same as that of DF(1) + D/sub 2/(0) (within 10%) when the endothermicities were considered.