Unstable intermediates. Part LXXV. Electron spin resonance studies of the effect of environment upon the hyperfine parameters for PO32– and NO32–

Abstract

The radicals PO₃^2– and NO₃^2–, formed in a variety of solids on exposure to high-energy radiation, have hyperfine parameters (³¹P and ¹⁴N) which are strongly dependent upon the nature of the host crystal. The results, which have been analysed in terms of s- and p-orbital contributions, show that, for PO₃^2–, the spin-density is strongly dependent upon the medium, with the p to s ratio increasing slightly as the spin-density on phosphorus falls. However, the spin-density on ¹⁴N in NO₃^2– is almost independent of the environment, but the p to s ratio is very sensitive to it. These results are discussed in terms of the trends observed within the isoelectronic families of these two radicals.