Non-isomorphic nucleation pathways arising from morphological transitions of liquid channels

TL;DR

This paper uncovers a new heterogeneous nucleation pathway involving morphological transitions of liquid channels, influenced by surface topologies, with implications for understanding diverse nucleation processes.

Contribution

It introduces a novel shape transition pathway in heterogeneous nucleation, supported by calculations and experiments, highlighting the role of surface features in nucleation behavior.

Findings

Identification of a pre-critical shape transition from channels to bulges

Demonstration of multiple energy barrier scenarios depending on supersaturation

Relevance of the pathway to common surface topologies like scratches and steps

Abstract

Motivated by unexpected morphologies of the emerging liquid phase (channels, bulges, droplets) at the edge of thin, melting alkane terraces, we propose a new heterogeneous nucleation pathway. The competition between bulk and interfacial energies and the boundary conditions determine the growth and shape of the liquid phase at the edge of the solid alkane terraces. Calculations and experiments reveal a "pre-critical" shape transition (channel-to-bulges) of the liquid before reaching its critical volume along a putative shape-conserving path. Bulk liquid emerges from the new shape, and depending on the degree of supersaturation, the new pathway may have two, one, or zero energy barriers. The findings are broadly relevant for many heterogeneous nucleation processes because the novel pathway is induced by common, widespread surface topologies (scratches, steps, etc.).