The ground and ν _6=1 vibrational levels of HC ~(35)Cl _3: The first high-resolution analysis of the ν 6 fundamental band

摘要

The paper reports on the first high-resolution study of the weak ν _6 fundamental rovibrational band of monoisotopic chloroform HC ~(35)Cl _3. More than 4500 infrared transitions pertaining to the ν _6 band have been assigned, spanning the rotational states J=0-95 and -73≤KΔK≤89. The new Fourier transform infrared data were combined with accurate submillimeter-wave transition frequencies in the v 6=1 state measured previously Journal of Molecular Structure 795; 2006: 157-162 in a simultaneous fit. The existence of resonance crossings due to the Δk=±1, Δl=?2 l-type resonance in the v 6=1 state, which generated perturbation-allowed rotational transitions, provided independent values of the C and Cζ 6 constants. When we combined them with the wavenumbers of the fundamental ν _6 band, we were able to determine accurately the axial rotational constants in the vibrational ground state C 0=0.05715783 (20) cm ~(-1), DK0=2.759 (63)10 -8cm ~(-1), and even HK0=-8.27 (75)10 -14cm ~(-1).