Manipulation of thin liquid films by means of infrared irradiation

par  Anton A. Darhuber, Eindhoven University of Technology, The Netherlands

Mardi 16 Juin, 14h, Salle des séminaires, 3ème étage, Batiment A4

This presentation showcases two possibilities for inducing flow and concentration non-uniformities in thin liquid films via modulated temperature distributions using infrared (IR) illumination. In the first case, an IR laser beam creates gradients in the surface tension giving rise to thermocapillary convection. On completely wetting substrates, we measured the film thinning dynamics with a resolution of 5-10 nm using interference microscopy. On partially wetting substrates, the local temperature increase accelerates the disjoining-pressure-driven destabilization of the thin liquid film. In the second case, we use a micro-mirror array to spatially and temporally modulate the evaporation rate of a volatile solvent. This leads to controlled pattern formation and deposition of dissolved macromolecules and dispersed nanoparticles on the substrate. We discovered two complementary deposition modes, where material accumulates either in the illuminated or the non-irradiated regions.