An FFT approach to the analysis of dynamic properties of gas/liquid interfaces

作者：Mariot Sandrine^*; Leroy Valentin; Pierre Juliette; Elias Florence; Bouthemy Eloise; Langevin Dominique; Drenckhan Wiebke

来源：Colloids and Surfaces A: Physicochemical and Engineering Aspects , 2015, 473: 11-17.

DOI：10.1016/j.colsurfa.2014.11.038

• Foams
• Surfactant monolayers
• Interfaces
• Electro-capillary wave
• Fourier-transform
• Surface visco-elasticity

The characterisation of the dynamic properties of viscoelastic monolayers of surfactants at the gas/liquid interface is very important in the analysis and prediction of foam stability. With most of the relevant dynamic processes being rapid (thermal fluctuation, film coalescence etc.) it is important to probe interfacial dynamics at high deformation rates. Today, only few techniques allow this, one of them being the characterisation of the propagation of electro-capillary waves on the liquid surface. Traditionally, this technique has been applied in a continuous mode (i.e. at constant frequency) in order to ensure reliable accuracy. Here we explore the possibility to analyse the propagation of an excited pulse in order to access the interfacial properties in one single Fourier treatment over a wide range of frequencies. The main advantage of this approach is that the measurement times and the required liquid volumes can be reduced significantly. This occurs at the cost of precision in the measurement, due partly to the presence of a pronounced resonance of the liquid surface. The pulsed approach may therefore be used to pre-scan the surface response before a more in-depth scan at constant frequency; or to follow the changes of the interfacial properties during surfactant adsorption.

• 出版日期2015-5-20