Influence of temperature on the collision broadening of IR spectral lines of CO2 molecules

The method of diode laser spectroscopy is used to measure the widths of the IR spectral lines of CO₂ molecules within wide ranges of temperatures (T = 170-600 K) and rotational quantum numbers (J ≤ 82). It is established that the existing quasi-classical models of collision broadening cannot describe all the experimental results. An improved model is offered that takes into account departures of the trajectories of moving particles from straight lines and an increase in the effective broadening cross section at small relative particle velocities due to orbital collisions. The model contains no free fitting parameters and satisfactorily describes experimental data. The scheme of averaging the broadening cross sections over the relative velocities of particles is refined.