SUB-DOPPLER HETERODYNE FREQUENCY MEASUREMENTS OF CARBONYL SULFIDE TRANSITIONS BETWEEN 56-THZ AND 62-THZ

We report the first sub-Doppler frequency measurements on carbonyl sulfide (OCS) between 56 and 62 THz (1886 and 2064 cm(-1)). The experiment utilizes heterodyne techniques to measure the frequency of a CO laser, which is locked to saturation dips of OCS transitions at low pressure, against combination frequencies of two saturation-stabilized CO2 lasers. For these measurements, ground state and hot band absorptions, we achieved absolute accuracies between 17 and 48 kHz. We fitted the results together with the existing data set to determine improved OCS transition frequencies for calibration of spectra in the 2000.cm(-1) region. In addition, by combining our new hot band measurements with existing frequency data for the lower energy levels, we provide improved transition frequencies for higher wavenumber regions. New calibration tables are given at 1890, 2050, and 2730 cm(-1). (C) 1994 Academic Press, Inc.