Heterodyne difference frequency measurements between a 13CO2 laser and a diode laser tuned (and in most cases locked) to the peaks of OCS absorption lines have been used to improve frequency calibration tables in the 860-cm-1 region by factors of 20–50. Measurements have been made on the vibrational transitions 1000-0000, 1110-0110, and 2000-1000 for OCS. The measurements on the 1000-0000 and 2000-1000 transitions are also used to provide frequency calibration tables for the 2000-0000 band of OCS near 1700 cm-1.
J. S. Wells, F. R. Petersen, A. G. Maki, and D. J. Sukle, "Heterodyne frequency measurements on the 11.6-µm band of OCS: new frequency/wavelength calibration tables for 11.6- and 5.8-µm OCS bands," Appl. Opt. 20, 1676-1684 (1981)