Probing Internal Stress and Crystallinity in Wet Foam via Raman Spectroscopy

TL;DR

This study uses Raman spectroscopy to investigate how internal stress and crystallinity in wet foam evolve over time, linking microscopic structural changes to vibrational spectral shifts.

Contribution

It demonstrates the correlation between internal stress, foam aging, and Raman spectral shifts, and reveals crystallinity in foam through long-term Raman analysis.

Findings

Internal stress correlates with Raman shift of methylene rocking mode.

Raman spectroscopy can detect crystallinity in wet foam.

Foam bubble size decreases over 24 hours.

Abstract

In this article, we correlate the internal stress and the characteristics of a vibrational mode in wet foam. Using microscope images, we estimate the average size of the bubbles in wet foam, at specific time intervals, over a duration of twenty four hours. Raman spectra are also recorded at the same time intervals, over the same time frame. We show that the internal stress, originated from the macroscopic structural change of foam with ageing, can be related to the observed Raman shift of the low frequency methylene rocking mode of the constituent surfactant molecules in foam. In this report we also show the capability of the Raman spectroscopy to reveal the crystallinity in foamy materials, when studied for a longer period of time.