The [formula omitted] band system of H 374GeF revisited: Analysis of a high-resolution FTIR spectrum

Abstract

The FTIR spectrum of monoisotopic H 3 74GeF recorded with a resolution of ∼2.5 × 10 −3 cm −1 (fwhm) has been investigated in the region of the ν 2 ν 5 band, ν 2 0 873.82345(2) and ν 5 0 873.98095(1) cm −1. Strong perturbations were observed, and different models were tested. With an interaction model comprisng q t (+) and r t resonance within ν 5 and Coriolis x, y, and α resonance between ν 2 and ν 5, ultimately 4768 rovibrational lines including 23 perturbation-allowed transitions were fitted to 32 excited state parameters with σ = 1.5 × 10 −4 cm −1. In addition, Δ K = ±3 perturbations between ν 2, K and ν 3, ( K + 3) levels and ν 5, kl and ν 6, ( kl − 3) sublevels were detected and fitted, and likely locations of similar perturbations in other halides H 3 EX of group IV elements E are predicted. The intensity perturbation M 2 ζ 2,5 y M 5 was found to be positive, and a transition moment ratio | M 2: M 5| = 0.77(5) was determined. In order to derive the equilibrium rotational constants for H 3 74GeF, A e = 2.63241(2) and B e = 0.3355664(8) cm −1, the ν 1 ν 4 band was studied by Doppler-limited FTIR spectroscopy and examined in some detail. Although abundant perturbations of nearly all K and kl levels, respectively, were substantiated, these were shown to be mostly of rotational type and local. About 650 almost unperturbed transitions with J′ ≦ 40 were selected and fitted to a model complete to quadratic diagonal terms, σ = 9 × 10 −4 cm −1. Effective band origins were determined, ν 1 0 2123.3031(1) and ν 4 0 2131.0359(1) cm −1.