Distribution of Positron Annihilation Lifetime Components

The intensities of the positron annihilation lifetime components are shown to be related to the free volume model, and the theoretical value of the ratio between the singlet to the triplet state intensities, described by the ratio η, is shown to follow an empirical model. An application of the model on some experimental data shows that the calculated value of the ratio η approaches the theoretical value, which is 1/3. Furthermore, the relation between the free volume hole fraction, Fh, with the free volume Vh described by the constant C is related to τ3. Therefore, the deviation of the constant C and the ratio η that are reported and differ from the theoretical values for similar researches could be corrected. When data are collected by means of positron annihilation lifetime spectroscopy (PALS), the spread-intensity model is suggested to explain this correction.