ESR of phosphite radicals trapped in x-irradiated single crystals of o-phosphorylethanolamine

Two different species of phosphite radicals are trapped at 300 K in x-irradiated single crystals of o-phosphorylethanolamine, H3N+CH2CH2OPO3H−. One radical, resulting from cleavage of the P–OH bond, is characterized by eigenvalues of 2173±16 MHz, 1733±19 MHz, and 1713±19 MHz, and 2.0065±0.0004, 2.0045±0.0004, and 2.0038±0.0004, for the hyperfine coupling tensor and g tensor, respectively. The other radical, produced by cleavage of the P–OCH2CH2NH+3 bond, has corresponding eigenvalues of 2131±15 MHz, 1710±15 MHz, and 1689±13 MHz, and 2.0054±0.0004, 2.0052±0.0004, and 2.0044±0.0004. Both radical species are present in approximately equal concentrations in the crystal, suggesting that both the P–OH and P–OCH2CH2NH+3 bonds are equally susceptable to electron dissociative capture, the assumed mechanism for radical formation.