The high-resolution Fourier transform infrared spectrum of H374Ge35Cl from 2000 to 2250 cm−1

Abstract The infrared spectrum from 2000 to 2250 cm −1 of monoisotopic H 3 74 Ge 35 Cl has been reinvestigated with a resolution (FWHM) of ca. 0.0030 cm −1 . Remarkable improvements have been achieved with respect to previous rovibrational investigations employing spectra with lower resolution. The assignments of the ν 1 fundamental have been extended, especially in the perturbed subbranches with 4 ≦ K ≦ 7, and the related transitions have been fitted with a standard deviation σ = 1.33 × 10 −3 cm −1 . The analysis of the local perturbations observed in almost all K Δ K branches of ν 4 , according to the proposed interaction model, has led to the identification of 37 vibrotational transitions belonging to combination and overtone vibrational levels which are enhanced near resonance by intensity stealing from ν 4 transitions. The fit of these 37 lines (σ = 5.72 × 10 −3 cm −1 ) and of 565 transitions of ν 4 (σ = 3.36 × 10 −3 cm −1 ) including the resolved R Q 0 lines, the corresponding R R 0 lines, and those lines of the locally perturbed regions which were disregarded in the previous analyses has allowed the determination of vibration-rotation parameters of 3 ν 3 + ν 5 , ν 2 + ν 3 + ν 5 , and 2 ν 2 + ν 3 , of the vibrational wavenumbers of ν 3 + 2 ν 5 ( A 1 ), ν 3 + 2 ν 5 ( E ), ν 2 + 3 ν 3 , and 5 ν 3 , and of several interaction constants. The resolution of numerous R Q 0 lines of ν 4 has enabled an improved determination of the l -doubling constant F 4 .