On positronium formation in binary mixtures of organic compounds

The intensities of the long-lived component I2 in the positron lifetime spectra were measured for a variety of mono- and dihalogenated benzenes, benzylalcohol, benzaldehyde, benzonitrile, and acetophenone in benzene solution. The results indicate that I2 is not an additive property, e.g., small amounts of bromobenzene (less than 0.1 mole fraction) added to benzene reduce I2 to the value observed in the pure compound. The capability of the various systems to effectively reduce I2 values as well as the minimum I2 values observed in these systems have been evaluated. The results are discussed in terms of the existing models of Ps formation and interactions in binary mixtures