PURE ROTATIONAL SPECTRA OF HNCS IN THE FAR-INFRARED - GROUND-STATE ANALYSIS

The pure rotational spectrum of HNCS was recorded under high resolutio n by a Michelson-type Fourier transform infrared spectrometer in the f ar-infrared region; also, some high-J submillimeter-wave transitions ( e.g., J = 91 <-- 90) near 1 THz were observed with the precision of mi crowave spectroscopy using a high-frequency backward wave oscillator. Effective molecular parameters have been determined for each K-a subst ate of HNCS up to K-a = 7, for DNCS up to K-a = 6, for (HNCS)-S-34 up to K-a = 5, and for some K-a substates of (HNCS)-C-13 and H (NCS)-N-15 , by fitting the available microwave and millimeter-wave transitions s imultaneously. The centrifugal distortion resonance has been clearly o bserved in HNCS and analyzed by a second-order perturbation treatment. (C) 1995 Academic Press, Inc.