A setup for studying the molecular structure of soap films held on a thin film balance with a synchrotron x-ray source
Abstract
Neighboring gas bubbles in liquid foams are separated by films whose interfaces are stabilized by adsorbed amphiphilic molecules. The equilibrium thickness of these films is in the nanometer range, depending on a balance of capillary suction pressure and disjoining pressure, due to competing attractive and repulsive interactions between the interfaces. Quantitative modeling of this balance raises many open questions, calling for experiments probing the internal molecular structure of free-standing individual liquid films with a well-controlled geometry and capillary pressure. Previous small-angle x-ray reflectivity studies of such liquid films had to rely on conventional x-ray sources. Up to hundreds of repeated experiments, each lasting times of the order of an hour, were performed to accumulate statistics sufficient for resolving precisely the electron density profile in a given kind of film. Therefore, the range of explored sample compositions, temperatures, and suction pressures remained strongly limited in this pioneering work. Modern synchrotron sources offer x-ray intensities orders of magnitude beyond those of conventional sources. However, to take advantage of this, a highly stable flat soap film must be obtained, free-standing in a gas saturated with humidity, at a controlled temperature and capillary pressure. We report the construction of a setup that meets these challenging technical requirements so that we can probe soap films with thicknesses in the nanometer range using a grazing incidence x-ray beam, and determine their electron density profiles with a total acquisition time of only 20 minutes for a given sample.
Related
- Time performance of USTC-IME LGAD under synchrotron light source focused X-ray
- Two-Phase Structure of Synchrotron-Cooling-Unstable Relativistic Plasma
- Measurements of the micro-spill structure of medical cyclotron and synchrotron beams and its impact on pulse pileup
- A Dual Vibrational Probe Framework for Studying Solvation in Highly Heterogeneous Molecular Environments
- Molecular representation shapes the balance between target fidelity and exploration in flow based polymer generation
BibTeX
@misc{bernard2026setup,
title = {{A setup for studying the molecular structure of soap films held on a thin film balance with a synchrotron x-ray source}},
author = {Mathieu Bernard and Sylvie Cohen-Addad and T El Atmani and Michel Goldmann and A Hemmerle and R Höhler and B Hosseinpour Paroshi and M Parise and O Pitois and Florence Rouyer},
howpublished = {HAL},
year = {2026},
month = sep,
url = {https://hal.science/hal-05749599v2},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - A setup for studying the molecular structure of soap films held on a thin film balance with a synchrotron x-ray source
AU - Mathieu Bernard
AU - Sylvie Cohen-Addad
AU - T El Atmani
AU - Michel Goldmann
AU - A Hemmerle
AU - R Höhler
AU - B Hosseinpour Paroshi
AU - M Parise
AU - O Pitois
AU - Florence Rouyer
PY - 2026
DA - 2026/09/14
PB - HAL
UR - https://hal.science/hal-05749599v2
AB - Neighboring gas bubbles in liquid foams are separated by films whose interfaces are stabilized by adsorbed amphiphilic molecules. The equilibrium thickness of these films is in the nanometer range, depending on a balance of capillary suction pressure and disjoining pressure, due to competing attractive and repulsive interactions between the interfaces. Quantitative modeling of this balance raises many open questions, calling for experiments probing the internal molecular structure of free-standing individual liquid films with a well-controlled geometry and capillary pressure. Previous small-angle x-ray reflectivity studies of such liquid films had to rely on conventional x-ray sources. Up to hundreds of repeated experiments, each lasting times of the order of an hour, were performed to accumulate statistics sufficient for resolving precisely the electron density profile in a given kind of film. Therefore, the range of explored sample compositions, temperatures, and suction pressures remained strongly limited in this pioneering work. Modern synchrotron sources offer x-ray intensities orders of magnitude beyond those of conventional sources. However, to take advantage of this, a highly stable flat soap film must be obtained, free-standing in a gas saturated with humidity, at a controlled temperature and capillary pressure. We report the construction of a setup that meets these challenging technical requirements so that we can probe soap films with thicknesses in the nanometer range using a grazing incidence x-ray beam, and determine their electron density profiles with a total acquisition time of only 20 minutes for a given sample.
ER -