SUB-DOPPLER FREQUENCY MEASUREMENTS ON OCS AT 87 THZ (3.4-MU-M) WITH THE CO OVERTONE LASER

Sub-Doppler frequency measurements have been made on three transitions of OCS in the 87-THz region (near 2900 cm(-1)). The CO overtone laser was used as the saturating laser. Polarization spectroscopic techniqu es utilizing optical heterodyne detection were used to observe the fea tures and subsequently provide the discriminant for locking the overto ne laser to the OCS transitions. A CO2 laser synthesizer was used to m easure the frequency of the CO overtone laser and thereby measure the frequencies of the OCS lines. The resulting frequencies of the three n ew measurements are: 10(0)1-00(0)0 P(27), 87 117 278.496(50) MHz; 11(1 f)1-01(1f)0 R(14), 87 222 001.143(70) MHz for OCS; and for the (OCS)-S -34 10(0)1-00(0)0 P(9), 87 010 586.667(75) MHz, where the numbers in p arentheses are the uncertainties in the last digits. These new numbers have been fitted along with more than 5700 other data points in our O CS data bank and improved constants have been obtained. These latest c onstants are used to calculate updated calibration tables containing v alues with much smaller uncertainties; three such tables are included. (C) 1994 Academic Press, Inc.