High resolution FTIR spectra of CD235Cl2; analysis of the n5/n7/n9 triad

The infrared spectra of isotopically pure (CD2Cl2)-Cl-35 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, nu(3) (weak), nu(7) (very weak), and nu(9) (strong). A satisfactory analysis of the observed spectra has been obtained by including a c-Coriolis coupling between nu(3) and v(9) and a b-Coriolis term between nu(7) and nu(9). Although no transitions could be observed for the very weak nu(7) band, its band origin could be estimated from the Coriolis interaction with nu (9). From the analysis of about 4200 assigned transitions of the nu(3) and nu(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.