TIME-RESOLVED PULSED FT-IR EMISSION STUDIES OF PHOTOCHEMICAL-REACTIONS

A time-resolved Fourier transform emission spectrometer, operating in the stop-scan mode, is demonstrated as an inexpensive and versatile in strument for observation of infrared vibrational chemiluminescence. Th e entire evolution of an emission spectrum is obtained from a single s can of the interferometer, with a spectral and temporal resolution of 2 cm-1 and 10 ns, respectively. Results are presented for a number of radical-radical reactions studied by this technique, where emission fr om highly excited CO, HF, CO2, and N2O is observed. Measurements inclu de nascent vibrational distributions, quantum yields for branching int o different product channels, and bimolecular rate constants for the p roduction and vibrational relaxation of product species. Experiments a t low total pressure enable nascent vibrational and rotational distrib utions to be found for the HF fragment of the CO2 laser photolysis of 1,1-chlorofluoroethylene. In addition, time-resolved spectra of HF, CO , CO2, CF4, and CHF3 are demonstrated for infrared emission observed f rom a reactive ion plasma etching chamber.