title: Monitoring particle adsorption by use of laser reflectometry near the critical angle.
abstract: We investigate the use of laser reflectometry near the critical angle to monitor particle adsorption onto a flat glass surface. Experimental results show that positive particles are adsorbed onto the glass surface and that their adsorption kinetics depend strongly on the volume fraction occupied by the particles in suspension but not appreciably on the particle size. The reflectance near the critical angle is dominated by the particles on the surface, with the contribution of the particles in suspension being very low. We compare the reflectance change near the critical angle with the change in reflectance near the Brewster angle when particles are adsorbed onto the glass surface. We find that reflectometry near the critical angle is 3000 times more sensitive than it is near the Brewster angle. Some optical images are presented to validate our results.
authors.affiliation: Institute de Física, Universidad Autónoma de San Luis Potosi, Alvaro Obregón 64, 78000 San Luis Potosi, San Luis Potosi, México. mgomar@ifisica.uaslp.mx
authors.forename: Mary Carmen
authors.initials: MC
authors.lastname: Peña-Gomar
authors.forename: Ma Lourdes
authors.initials: ML
authors.lastname: González-González
authors.forename: Augusto
authors.initials: A
authors.lastname: García-Valenzuela
authors.forename: Joan
authors.initials: J
authors.lastname: Antó-Roca
authors.forename: Elías
authors.initials: E
authors.lastname: Pérez