Electron Spin Resonance Identification of an N2− Defect in X-Irradiated Sodium Azide

• Published in: The Journal of chemical physics 1966-01, Vol.45 (5), p.1703-1709
• Main Authors: Gelerinter, Edward, Silsbee, Robert H.
• Format: Article
• Language: English
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.1727818

A defect is produced in sodium azide (NaN3) by exposing it to x rays and is studied using the ESR (electron spin resonance) technique in the frequency range of 10–70 kMc/sec. The observed spectrum agrees with the theoretical predictions made using a model of an N2− ion in the azide position with the surroundings frozen in a Jahn—Teller distortion. Since the azide ion is in a position of trigonal symmetry, there are three such distortions, and there is experimental evidence that these three distortions are equally populated. The absence of experimental evidence for tunneling does not necessarily imply correspondingly low tunneling matrix elements, but instead may be the result of stabilization of the static states by the strain which is known, from x-ray data, to be present. These strains are also responsible for some of the observed line broadenings. The available crystals are heavily twinned, so that it is necessary to correlate x-ray and ESR data in order to remove the ambiguities associated with this twinning.