SPECTRAL BAND WINGS AND RATE CONSTANTS OF ROTATIONAL RELAXATION AS DATA SOURCE ON MOLECULAR TORQUES

The factor T-4(Delta omega) describing the intensity distribution at l arge detunings aw from a vibrational band centre is calculated for cla ssical linear rotators in a buffer monoatomic gas. A formalism develop ed uses the theory of moments and is appropriate for a spectroscopy of any rank. The invariant form of the interaction potential and the irr educible tensor approach are exploited to derive the third- and fourth -order Poisson I,rackets of spectroscopic quantities. The anisotropy o f the pair distribution function is analytically incorporated in the f ormulas for zeroth and second moments of the torque spectra appearing in the wing distributions. By a similar technique, the relaxation rate s of rotational energy and momentum are studied. Useful analytical rel ations are found in the fast-collision limit. Calculations performed f or CO + He and CO2 + He systems permit one to check the accuracy of th e current models based on the infinite order sudden approximation and are in reasonable agreement with available experimental IR and NMR dat a.