Boojums and the Shapes of Domains in Monolayer Films

TL;DR

This paper investigates how boojum textures influence the shape of domains and bubbles in Langmuir monolayers through experimental and theoretical methods, revealing a qualitative understanding of their relationship.

Contribution

It provides the first combined experimental and theoretical analysis of boojum textures affecting domain and bubble shapes in Langmuir monolayers.

Findings

Boojum textures cause cusp-like features on domain boundaries.

Inverse boojum textures distort gas-like bubbles in monolayers.

Qualitative agreement between theory and experiment has been achieved.

Abstract

Domains in Langmuir monolayers support a texture that is the two-dimensional version of the feature known as a boojum. Such a texture has a quantifiable effect on the shape of the domain with which it is associated. The most noticeable consequence is a cusp-like feature on the domain boundary. We report the results of an experimental and theoretical investigation of the shape of a domain in a Langmuir monolayer. A further aspect of the investigation is the study of the shape of a ``bubble'' of gas-like phase in such a monolayer. This structure supports a texture having the form of an inverse boojum. The distortion of a bubble resulting from this texture is also studied. The correspondence between theory and experiment, while not perfect, indicates that a qualitative understanding of the relationship between textures and domain shapes has been achieved.