High-Resolution FTIR Spectra of CD235Cl2: Analysis of the v3/v7/v9 Triad

The infrared spectra of isotopically pure CD235Cl2 have been recorded at a resolution of 0.0026 cm-1 (FWHM) in the range 600-1160 cm-1 with a Bruker IFS 120 HR Fourier transform interferometer. The absorption between 670 and 750 cm-1 is due to three fundamentals, ?3 (weak), ?7 (very weak), and ?9 (strong). A satisfactory analysis of the observed spectra has been obtained by including a c-Coriolis coupling between ?3 and ?9 and a b-Coriolis term between ?7 and ?9. Although no transitions could be observed for the very weak ?7 band, its band origin could be estimated from the Coriolis interaction with ?9. From the analysis of about 4200 assigned transitions of the ?3 and ?9 bands, excited state constants have been determined up to sextic terms. The Coriolis parameters obtained are compared to those calculated from a harmonic force field.