High-information time-resolved Fourier transform spectroscopy at work

The first instrumental setup, to our knowledge, that is capable of recordin g in a few hours the time-resolved Fourier transform (TRFT) interferograms of gas-phase spectra that cover several thousands of inverse centimeters wi th spectral- and time-resolution limits that are equal, at best, to 2.5 x 1 0(-3) cm(-1) and 2 ns, respectively, is reported. It was developed on the s tepping-mode Connes-type interferometer of the Laboratoire de Photophysique Moleculaire Universite de Paris Sud. Also, for the first time, to our know ledge, these high-resolution TRFT spectra, illustrated with the Doppler-lim ited emission spectra of the N-2 transitions (B-A) and (B'-B) between 5500 and 11 000 cm(-1) and of the atomic Ar Lines between 1800 and 4000 cm(-1), are recorded in the infrared spectral range. To obtain identical results th at have the same signal-to-noise ratio, we should have increased the record ing time of our unique previous high-information TRFT spectra by approximat ely 50,000. In other words, one hour is now long enough to obtain what woul d previously have required six years to record. (C) 2000 Optical Society of America OCIS codes: 300.6500, 300.6300, 120.3180.