Positron Annihilation in and Compressibility of Water-Alcohol Mixtures

Abstract

In our recent paper we found that long lived component of lifetime spectrum τ2, which is connected with pick-off ortho-positronium annihilation and its intensity do not change monotonically with the concentration of organic components in water. The results obtained confirm the thesis of quasi-crystalline, clathrate-like structure of water-tetrahydrofuran and water-cyclohexylamine systems. The attempt of the present work was to study the structure of water-ethanol, water-n-propanol and water-isopropanol mixtures, their clathrate-likeness and stoichiometry, if any. The results of our measurements of positronium lifetime, in particular the component τ2 and the intensity I2 as well as the sound velocity data allow us to suppose that in the systems the liquid clathrate-like hydrates are formed. The stoichiometry of these structures was deduced. The results, although obtained using strongly different experimental methods, i.e., positron annihilation and acoustic measurements, are in very good agreement with the clathrate-like concept of the structure of water-organic mixtures.