EPR of O2 Impurity in Solid N2, CO, Ar, and CD4 Prepared from the Vapor

Abstract

The EPR spectra of O2 impurity in specimens of N2, CO, Ar, and CD4 condensed from the gas at 4.2°K have been studied at X- and K-band frequencies. For the N2 host, studies have been made of the effect of varying concentration and temperature. The polycrystalline absorption profiles for N2 and CO show structure and are analyzed. Those for Ar and CD4 show only broad structureless absorption. The results show that in N2 and CO the O2 molecules occupy isolated and essentially axial symmetry sites at low concentrations but that new features, attributed to different sites arising from clustering or defects, appear at higher concentrations. The extraction of useful information is limited by the polycrystalline nature of the samples.