High-resolution FTIR spectroscopy of chlorodifluoromethane: ν2 and ν7 Original Research Article

High-resolution FTIR spectra of chlorodifluoromethane (R22) were measured both at room temperature and cooled to approximately −100 °C in a collisional cooling cell. A rovibrational analysis was performed for ν2, the a/c-hybrid band at 1313 cm−1 and ν7, the b-type band at 1351 cm−1. 7400 and 1700 lines were assigned to CH35ClF2 and CH37ClF2, respectively, with quantum numbers up to J=98 and Ka=46. Effective constants to the sextic level have been fitted using Watsonʹs A-reduction Hamiltonian. More accurate spectroscopic constants were obtained by fitting the two states simultaneously, taking into account both first- and second-order c-axis Coriolis interactions between the two bands. The ν2 band is predominantly a-type, but weaker c-type transitions assigned for CH35ClF2 enable the a/c-hybrid character (μa2/μc2) to be determined as 5.76.