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The nine-line magnetic resonance spectrum of N"0" is observed at 6elds in the range of 8600 oersted at a frequency of 9360 megacycle/sec. The spectrum arises from magnetic-dipole transitions between Zeeman levels in the J=-, state of the 'II3~~spin component. The line positions allow a determination of the magnetic IJ coupling constant, which is 29.8~0.3 megacycle /sec. , and the nuclear electric quadrupole coupling, which is -1.7~0.5 megacycle /sec, The line position and triplet spacings, which arise from molecular perturbations, are in good agreement with the theory of Margenau and Henry. The absolute intensity of the three stronger lines is measured to be g"=1.2X10 ' which also agrees with theory.

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Spin relaxation has been measured at 3 kOe and at lattice temperatures from 1.24 ° to 250 0 K for the E' centers generated in one type of vitreous silica by 2-MeV gamma rays. An unusual temperature dependence was found in which the spin-lattice relaxation time varies roughly as T-2,5 over most of the range. All of the data are accurately fitted by analytical functions derived from a coupling of the individual defect centers to the vitreous host involving excess local strain due to mechanical resonances of about 4.1 X 1011 and 6.0X 10 12 cps at each E' center. The strength of the coupling and the characteristic frequencies of mechanical resonance are similar to those in crystalline SiO •. 9