EPR of O2 Impurity in Solid N2

The EPR spectrum of O₂ impurity in solid N₂ has been observed at K band and at X band. The results are consistent with the specific‐heat results for this system and indicate that the ${}^3\Sigma$ state is split in zero field by 105 ± 15 GHz. A small temperature‐dependent splitting of the upper doublet is indicated by the results, and the possibility of using O₂ as a probe to investigate the motions of molecular solids is pointed out.