title: Surface fluctuations of liquids confined on flat and patterned solid substrates.
abstract: We report experimental measurements of the surface fluctuations of micron-thick oil films spread onto a solid substrate. We use a recently developed optical technique based on the measurement of the deflection of a laser beam triggered by changes in the local surface slope. When the liquid is spread on a flat substrate, fluctuation dynamics slow down as the thickness is decreased, in quantitative agreement with previous predictions. In addition, we investigate the consequences on surface fluctuations of the patterning of the substrate with a rectangular grating. For liquid film thicknesses smaller than the typical wavelength probed, we demonstrate that surface fluctuations are modified by the underlying pattern: The shape of the fluctuation spectra varies periodically with the spatial position over the pattern and, in addition, the fluctuations become locally anisotropic. However, the spatially averaged spectrum is isotropic.
authors.affiliation: UPMC, CNRS, ESPCI Paris-Tech, UMR 7615, Laboratoire SIMM, 10 rue Vauquelin, F-75231 Paris Cedex 05, France.
authors.forename: Basile
authors.initials: B
authors.lastname: Pottier
authors.affiliation: UPMC, CNRS, ESPCI Paris-Tech, UMR 7615, Laboratoire SIMM, 10 rue Vauquelin, F-75231 Paris Cedex 05, France.
authors.forename: Emilie
authors.initials: E
authors.lastname: Verneuil
authors.affiliation: UPMC, CNRS, ESPCI Paris-Tech, UMR 7615, Laboratoire SIMM, 10 rue Vauquelin, F-75231 Paris Cedex 05, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Talini
authors.affiliation: Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, F-69622 Villeurbanne Cedex, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Pierre-Louis