Adsorption of rhodamine 6G at the water-air interface

Abstract

We wanted to detect and quantify adsorption of Rhodamine 6G (R6G) at the air/water interface to supplement previous work using second harmonic generation [1-4]. We found that at incidence angles close to the Brewster angle this can be achieved, even at very low bulk concentration. Fitting to a single film model, we found that adsorption can be measured down to very low concentrations of 10-7 M. This is contrasted with the behaviour of other dyes and other solvents. Outside the wavelength range of the dye absorption band the refractive index of the surface approaches that of pure water. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.