MASS EFFECT IN THE LYOLUMINESCENCE YIELD FROM THE TISSUE-EQUIVALENT DOSIMETRIC MATERIALS

The role of the so-called 'mass effect' or 'self-quenching' in the lyoluminescence (LL) is often underplayed. The mass effect or self-quenching in LL yield is the non-linear rapid quenching of LL/mg with linear increase in mass of the solute, for any particular dose of radiation. Present experiments have proved that: (i) no relation exists between the 'quenching (absorption) coefficients' and the molar volume of the solute, (ii) the mass/cm2 is not the effective parameter in this case unlike thick beta-emitters, (iii) a chemiluminescent sensitizer, eosin used in solvent water effects no change in the nature of quenching, and (iv) increase of total mass by adding unirradiated LL material show that the yield LL/mg depends only on the mass of the activated phosphor, indicating the absence of the role of molecular scattering in the LL yield. The experiments indicate that the so-called mass effect or self-quenching is a fundamentally important physical phenomenon and quenching depends only on the number of free radicals formed due to irradiation, under a particular thermodynamic condition.