The identification of a paramagnetic center inggr;hyphen;irradiated sodium bromate crystals as the ozonide ion, O3minus;, is confirmed. At ambient temperatures the principal values of the axially symmetric g tensor are found to begVerbar;thinsp;equals;thinsp;2.0035thinsp;plusmn;thinsp;0.0001andgperp;thinsp;equals;thinsp;2.0220thinsp;plusmn;thinsp;0.0001, whereas at 77deg;K,gVerbar;thinsp;equals;thinsp;2.0028thinsp;plusmn;thinsp;0.0001andgperp;thinsp;equals;thinsp;2.0242thinsp;plusmn;thinsp;0.0001. If the O3minus;ion is a bent molecule of bond angle 110thinsp;plusmn;thinsp;5deg; the electron spin resonance data suggests that the O3minus;ion is undergoing rapid motion at ambient temperatures and that the rate of motion is reduced at 77deg;K. Because no brominehyphen;containing radical is characterized after the ambient temperature irradiation of sodium bromate, the electron spin resonance results suggest a radiolytic decomposition differing from that of the alkalinehyphen;earth bromates, in which the paramagnetic species BrO2is postulated.
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