Heterodyne frequency measurements of carbonyl sulfide transitions at 26 and 51 THz. Improved OCS, O 13CS, and OC 34S molecular constants

Heterodyne frequency measurements were made on selected absorption features of carbonyl sulfide (OCS) near 26 THz (860 cm ^-1) and 51 THz (1700 cm ^-1). Frequency differences were measured between a tunable diode laser (TDL) locked to carbonyl sulfide absorption lines and either a stabilized ¹³CO ₂ laser or a CO laser which was referred to stabilized CO ₂ lasers. These measurements are combined with conventional TDL measurements and published microwave measurements to obtain new, more reliable molecular constants for OCS, O ¹³CS, and OC ³⁴S. New frequency measurements are given for nine CO laser transitions between 1686 and 1726 cm ^-1.