ESR of 17O-Labeled Nitrogen Dioxide Trapped in a Single Crystal of Sodium Nitrite

A study is reported of the ESR spectrum of NO₂–¹⁷O formed by $\gamma$ irradiation of single crystals of NaNO₂–¹⁷O at 77°K. Hyperfine splittings due to ¹⁴N and ¹⁷O were studied as a function of orientation, and the principal values and directions of the hyperfine tensors determined. The results for the nitrogen hyperfine and $g$ tensor agree with those of Zeldes and Livingston. In a general orientation, splittings are observed due to two magntically inequivalent oxygens. The magnitudes of the principal values for the hyperfine tensors of both oxygens are:4.27, 54.90, and 1.74 G. The directions of the largest principal values are in the molecular plane at angles of + 7.5° and − 7.5° to the molecular axis. The results are used to derive values for the MO coefficients of the ${\text{4a}}_1$ orbital which contains the unpaired electron. An attempt is made to interpret the $g$ tensor in terms of the electronic structure of NO₂.