The infrared spectrum of CH3D between 900 and 3200 cm−1: extended assignment and modeling

Abstract

The high resolution infrared spectrum of CH3D in the region from 900 to 3200cm−1 has been analyzed on the basis of Fourier transform spectra recorded at Kitt Peak and at Giessen. A theoretical model for an effective hamiltonian in terms of irreducible tensor operators recently adapted to symmetric top molecules has been used in order to consider simultaneously all available transitions between the lowest three polyads of the molecule: the Ground State (G.S.), the Triad (three interacting fundamental bands in the 8μm region) and the Nonad (nine interacting bands in the 4μm region). A preliminary simultaneous fit of 3467 Triad–G.S., 5208 Nonad–G.S., and 2487 Nonad–Triad (hot band) transition wavenumbers has been done. The standard deviations achieved were 2.1, 4.7 and 4.3×10−3cm−1, respectively. A preliminary analysis of the transition intensities was also undertaken at a level of precision of the order of 5% or better.