UF6–H2 Hydrogen Fluoride Chemical Laser: Operation and Chemistry

Abstract

Continued study of the UF6–H2 hydrogen fluoride chemical laser has revealed conditions for which collisional deactivation is probably negligible and for which the rotational temperature is well defined and can be determined. Addition of inert gases (SF6, C2F6, He) moderates the temperature rise and reduces the number of transitions observed. For a mixture of UF6:H2 = 1:1 with 10–20-fold excess of SF6 or C2F6, the temperature rise is no more than 5°–10° at the time the first transition reaches threshold [P2(3) for HF, P3(5) for DF]. This observation and the time needed to transfer maximum gain to the next transition provide preliminary estimates of the rate-constant ratios, k3 / k2 = 0.83–1.11 for DF and k2 / k1 ≥ 1.0 for HF. These ratios are probably applicable, respectively, to the reactions of fluorine atoms with deuterium and hydrogen. The DF intensity of the UF6–HD laser indicates the fluorine atom abstracts hydrogen from HD 212 times as fast as deuterium. Quenching by various additives (HCl, DCl, CO2) suggests that complex formation plays a role. Without these additives, accumulated HF probably accounts for the quenching, which is particularly effective because both complex formation and resonance energy transfer are operative.