HF Vibrational Relaxation Measurements Using the Combined Shock Tube-Laser-Induced Fluorescence Technique

Abstract

Vibrational relaxation measurements in HF have been obtained at intermediate temperatures by combining the laser-induced fluorescence technique with shock compression heating in a shock tube. Usually, shock tube measurements of vibrational relaxation are limited to high temperatures, above about 1300°K in the case of HF. Laser-induced fluorescence measurements can be made in heated cells suitable for HF handling up to about 700–800°K. The combination of the two techniques offers several advantages including large range of temperatures, no wall reactions, and no leaky cells at high temperature. This method was used to obtain HF vibrational relaxation data at 460 to 1030°K and at 295°K. These data, together with shock tube data at high temperature (1350 to 3000°K), are compared with theoretical predictions. A measurement of the V-V rate for the reaction HF (1) + HF (1) ⇌ HF (0) + HF(2) gave a value of 2.2 × 1013 cc/mole · sec.