High-Resolution Infrared Spectra and Harmonic Force Field of Chlorine Nitrate

Infrared gas-phase absorption spectra of chlorine nitrate were recorded by high-resolution Fourier transform spectroscopy. By use of natural and of 35Cl-enriched ClONO2 samples, the isotopic wavenumber shifts of some fundamental vibrations of 35ClONO2 and 37ClONO could be determined. The measured isotopic shifts, together with published spectroscopic data (vibrational wavenumbers of ClO15NO2, centrifugal distortion constants of 35ClONO2 and 37ClONO2, and mean vibrational amplitudes), were used to calculate the harmonic force field of ClONO2. The new force field is compared with a recent ab initio calculation of the electronic ground state of ClONO2.