Static magnetic susceptibility measurements for 4°K < T < 300°K are reported for the following dioxygenyl salts: O2AsF6, O2SbF6, O2Sb2F11, and O2PtF6. In contrast to previous studies, we find both spin–orbit coupling and crystal field effects to be important. While the As and Sb compounds are paramagnetic at 4.2°K and have small O2+–O2+ exchange, O2PtF6 is ordered at 4.2°K, probably due to O2+–Pt(V) exchange. ESR studies confirm the susceptibility results, except in O2PtF6 where a resonance was not detected, and show that the O2+ magnetic state is described by an axial spin Hamiltonian with g⊥ ∼ 1.98 and g∥ ∼ 1.74. The ESR linewidth of O2AsF6 below 70°K is ∼ 80 G. Above 100°K the linewidth rapidly increases so that above 180°K the line is unobservable. This increase may be due to O2+ motion. NMR shows that the AsF6 groups in O2AsF6 are also rotating above 200°K, probably in some hindered form.
Irradiation of o~-A1203 (Corundum) was carried out in contact with acidic media and with different doses (100-to-2500 kGy) and dose-rates (0.9, 2.6 and 6.1 kGy.h 1) of y-rays. Simultaneously parallel experiments were carried out using the same procedure, but preheated at 150 ~ for two days and then irradiated without acidic media. The solid thus obtained was used to determine the effect of y-irradiation on the sorption capacities of microamounts of fission products from strongly alkaline aqueous solutions of uranium. The results revealed that the effect of y-irradiation of c~-A1203 and the acidic media in which it is immersed, is associated with a stable matrix resistant to significant changes in the composition of the surface layer; whilst it seems that the effect of y-irradiation of preheated c~-A1203, is connected with changes of surface OH groups strongly affected by heat treatment and irradiation dose.
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