Direct observation of homogeneous cavitation in nanopores

TL;DR

This study demonstrates that homogeneous cavitation is a key evaporation mechanism in nanoporous alumina and silicon membranes, with cavitation rates aligning with classical nucleation theory, offering new insights into liquid behavior in confined, metastable states.

Contribution

First experimental evidence of homogeneous cavitation in nanopores, confirming classical nucleation theory predictions in mesoporous materials.

Findings

Cavitation occurs in nanopores with narrow constrictions.

Cavitation rates match classical nucleation theory.

Porous alumina membranes are effective for studying metastable liquids.

Abstract

We report on the evaporation of hexane from porous alumina and silicon membranes. These membranes contain billions of independent nanopores tailored to an ink-bottle shape, where a cavity several tens of nanometers in diameter is separated from the bulk vapor by a constriction. For alumina membranes with narrow enough constrictions, we demonstrate that cavity evaporation proceeds by cavitation. Measurements of the pressure dependence of the cavitation rate follow the predictions of the bulk, homogeneous, classical nucleation theory, definitively establishing the relevance of homogeneous cavitation as an evaporation mechanism in mesoporous materials. Our results imply that porous alumina membranes are a promising new system to study liquids in a deeply metastable state.