FAST TIME-RESOLVED FOURIER-TRANSFORM SPECTROSCOPY FOR THE STUDY OF TRANSIENT-CHEMICAL REACTIONS

We describe the most recent implementation of the data acquisition sys tem which we have developed for fast time-resolved (FTR) Fourier trans form spectroscopy (FTS) and report spectra that were obtained by using this instrument. This FTRFTS data system operates in conjunction with any continuous-scan Michelson interferometer, giving it the capabilit y to record many time-delayed spectra of a transient event, with a min imum time resolution of 1 mu s. The sensitivity and the spectral resol ution of the complete system are the same as those that would be obtai ned if the interferometer were used in conventional steady-state spect roscopy. To illustrate the performance of the FTRFTS system, we record ed emission spectra from the products of transient chemical reactions of H atoms with CF3Cl, CF2Cl2, CFCl3, and NO2. These are laser-initiat ed reactions involving atoms with energies that correspond to a temper ature of approximately 27,000 K and lifetimes of a few microseconds, b ut the FTRFTS system records the time evolution of their products with high signal-to-noise ratio. (C) 1996 Optical Society of America