Probing Molecules Adsorbed at the Surface of Nanometer Colloidal Particles by Optical Second-Harmonic Generation

It is observed that optical second-harmonic generation from molecules adsorbed at the surface of nanometer size colloidal particles occurs at angles as large as 90° away from the fundamental beam direction. This phenomenon can be rigorously described by the nonlinear Rayleigh-Gans-Debye theory and used for probing molecules adsorbed on nanometer size colloidal particles.