Chemical laser grating selection measurements of initial vibrational energy distribution by reactions of F atoms with H2, CH4, C2H6

The complete product vibrational energy distribution from F+H2, CH4, C2H6 reactions was determined by the chemical laser grating selection (CLG) technique. Three important factors—vibrational relaxation and secondary reaction, rotational nonequilibrium, and superradiance were carefully investigated by time-resolved laser spectroscopy and analyzed by computer modeling. It was found that by using lower reactant pressure, these disadvantageous effects, which may have influenced the results of previous chemical laser studies, could be minimized or eliminated experimentally. It was also found that for these reactions, the accurate values of N2/N1 and N3/N2 could be obtained from the experiment or modeling calculation; in contrast, the value of N1/N0 was very high and was sensitive to vibrational relaxation and secondary reaction processes. In general, the results of the CLG method, at least for these reactions, are of the same degree of accuracy as those of the infrared chemiluminescence method. The rotational equilibrium assumption is still valid and can be used without apparent effect on the experimental results.