Measurement of positron lifetime to probe the mixed molecular states of liquid water

TL;DR

This study measures positron lifetime in liquid water across temperatures to understand molecular states, revealing a temperature-dependent decrease in ortho-positronium lifetime explained by combined models.

Contribution

It provides the first detailed positron lifetime analysis of liquid water's molecular states over a temperature range, integrating the Ps-bubble and mixture state models.

Findings

Ortho-positronium lifetime decreases by 10% from 0°C to 50°C.

The lifetime change is explained by a combined Ps-bubble and mixture state model.

Results support the molecular state transition hypothesis in liquid water.

Abstract

Positron lifetime spectra were measured in liquid water at temperatures between 0c and 50c. The long lifetime of ortho-positronium atoms (o-Ps) determined by electron pick-off in molecular substances decreases smoothly by 10% as the temperature is raised. This lifetime temperature dependence can be explained by combining the Ps-bubble model and the mixture state model of liquid water.