Microstructural study of supported liquid membranes using slow positron beam

摘要

Pore architecture in four supported liquid membranes (PTFE membranes) has been investigated using beam based positron annihilation spectroscopy (PAS) with variable positron energy (0.2-10 keV). Formation of positronium (Ps), its diffusion, re-emission and annihilation at various depths of the membranes have been investigated. It was observed that o-Ps 3γ/2γ annihilation ratio is a sensitive method to study the porernarchitecture. The 3γ/2γ curves are utilized to calculate diffusion length of o-Ps in the membranes. The o-Ps diffusion length measures the mobility of o-Ps in the membranes and represents pore interconnectivity, which in turn point to the tortuosity of the membrane. The relative open porosity in the membranes is measured by studying the 3γ/2γ profiles in the membranes capped with thin gold layer.