General rotational relaxation matrix: Linewidths for oxygen, their interrelation and relation to theory

Abstract

The interrelation of linewidth measurements for molecular oxygen EPR, millimeter wavelength, and infrared and Raman rotational transitions is described. These kinds of linewidth measurements are interrelated through a limited set of parameters which are sensitive to the nature of collision dynamics and intermolecular potentials. The limitations on these parameters set by theory are discussed, and expected magnitudes of the parameters in the weak-collision and statistical limits are described. The relative magnitudes of the parameters also provide a direct experimental test of approximate theories in which time ordering is neglected. Analysis of the N=1 EPR transitions for oxygen self-broadening indicate that pure reorientation cross sections are small compared with the cross section for rotational energy transfer from the N=1 states. The magnitudes of the experimental parameters for N=1 are best represented by a statistical model.