ESR STUDY OF ELECTRON INTERACTION IN A TC AL2O3 SYSTEM/

An investigation was made into the nature of paramagnetic centers in a Tc/Al2O3 system under varying conditions as to heat treatment and tec hnetium content, and in O2 and CO adsorption environments. It was foun d that in the case of reduction at 573 K Tc2+ ions and, conceivably, o ther ionic forms developed and stabilized on the carrier surface. Afte r reduction at 973 K two types of electron center appeared, whose conc entration increased as reduction was prolonged. Signals were observed in the low fields (3-20 mT) of the ESR spectra having g1 almost-equal- to 13.5 and 92 > 30, which could he assigned to free charge carriers i n a cluster of metal atoms or ions. Adsorption of O2 at 300 K caused O 2- ion radicals to form on the surface of the reduced Tc/Al2O3 Samples , both electron centers and technetium ions constituting the electron donors. In the case of CO adsorption paramagnetic (CO)2- particles app eared on the Tc/Al2O3 samples after prolonged exposure. On reaction wi th O2 two types of O2- ion-radical with differing thermal stability we re formed.