Vibrational spectra and force constants of symmetric tops

Abstract
The infrared absorption spectrum of monoisotopic 74GeH3 35Cl in the region of the rocking fundamental v 6 near 600 cm-1 has been investigated at a resolution near 0·04 cm-1. For the fundamental over 1600 ΔK = ± 1, ΔJ = ± 1 lines have been measured and assigned, and fitted by a least squares procedure providing eight molecular parameters of the ν6 = 1 state to a root mean square (r.m.s.) deviation of 7·7 × 10-3 cm-1. The hot bands v 6 + v 3 - v 3 and 2v 6 ±2 - v 6 ±1 have been identified and their QK peaks measured and assigned ; the derived vibrational anharmonicities are in good agreement with those found for related molecules.