Rotational spectra of the linear C3S molecule in the excited bending vibrational states ν5 = 1, 2, 3, and 4 (CCS bending) and ν4 = 1 (CCC bending) have been observed in the frequency range 116-383 GHz with a source-modulated microwave spectrometer. Molecular constants of vibration-rotation interaction terms up to higher orders were determined by the least-squares fitting of about 460 transition frequencies. The determined αt, qt, and qJt constants showed a good coincidence with those of ab initio calculation. The sign and magnitude of γll, the dependence of the rotational constant Bv on vibrational angular momentum, was explained by a symmetric-top-like molecular model. The constant qKt, the dependence of the l-type doubling and resonance constant qt on vibrational angular momentum, was determined experimentally for the first time. The obtained value of qKt was a thousand times greater than the theoretical estimate given by Watson′s expression, but the order of magnitude of the experimental value can be understood by an analogy with a slightly asymmetric-top molecule.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Physical and Theoretical Chemistry