AN ESR STUDY OF NH3-CENTER-DOT RADICAL IN ALKALI FELDSPARS( AL CENTERAND HO2)

Paramagnetic centers of NH3+, Al, and HO2 . have been observed in alka li feldspars from Aichi prefecture, Japan. The quartet signal has been tentatively ascribed to NH3+ rather than to . CH3, although the hyper fine splitting by N-14 (I = 1) was not observed. The average g- and A- values g(av) = 2.0033 and A(av)(H) = 2.45 mT, respectively, were attri buted to hydrogen. The powder spectra of Al centers stable up to 400 K were simulated by the anisotropic g factors of g(zz) = 2.060, g(xx) = 2.0014, g(yy) = 2.0021 and A = 0.9 mT. Newly discovered HO2- is stabl e up to 570 K. The intensities of the spectra from NH3+ and Al centers were enhanced by gamma-ray irradiation, while that of HO2- was not en hanced. Production efficiency, G-value (radical/100 eV) of NH3+ has be en obtained to be G = 0.01. These results suggest that ESR dating of f eldspars is possible.