ANALYTICAL APPLICATION OF POSITRON LIFETIME SPECTROSCOPY IN THE CHARACTERIZATION OF BINARY SOLID-SOLUTIONS

Positron Lifetime Spectroscopy (LS) measurements were performed in a s eries of binary molecular solid solutions of the general formula M(1-x )G(x)L(3), where L (ligand)=acetylacetone, dipivaloylmethane, or N-ben zoyl-N-phenylhydroxylamine, M=Al(III), Ga(III) or In(III), as matrix, and G=Cr(III), Mn(III), Fe(III), Co(III), Ru(III), Rh(III) and Ir(III) , as guest molecules, and the corresponding mechanical mixtures. For t he solid solutions, the o-Ps yield values (I-3) decrease very rapidly with the increase of the guest mole fraction, showing a high efficient Ps inhibition process, while for the corresponding mechanical mixture s, these values decrease linearly with the increase of the ''guest'' m olecule concentration, indicating the presence of two distinct phases. These results confirm our previous proposal that the LS technique is able to characterize solid solutions formed by one matrix, in which I- 3 values are high, and one guest, in which the I-3 values are very low .