Boundary Condition in Liquid Thin Films Revealed through the Thermal Fluctuations of Their Free Surfaces

• Published in: Physical review letters Vol. 114; no. 22; p. 227801
• Main Authors: Pottier, B, Frétigny, C, Talini, L
• Format: Journal Article
• Language: English
• Published: United States American Physical Society 05-06-2015
• Subjects: Boundary conditions; Film thickness; Fluctuation; Hydrodynamics; Liquid films; Liquids; Models, Chemical; Nanostructure; Nanotechnology - methods; Physics; Silicon - chemistry; Surface force apparatus; Surface Properties; Thin films; Walls
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.114.227801

We investigate the properties of nanometric liquid films with a new noninvasive technique. We measure the spontaneous thermal fluctuations of the free surfaces of liquids to probe their hydrodynamic boundary condition at a solid wall. The surface fluctuations of a silicon oil film could be described with a no-slip boundary condition for film thicknesses down to 20 nm. Oppositely, a 4 nm negative slip length had to be introduced to describe the behavior of n-hexadecane, consistently with previous surface force apparatus data on the same system. Our results demonstrate that at vanishing flow a nanometric solidlike layer close to the wall may exist according to the nature of the liquid.