Concentration dependence of Surface Non-linear Susceptibility of Vanadyl-Porphyrin at silica surfaces

Abstract

Resonant molecular optical second harmonic generation (SHG) has been obtained from [2, 3, 7, 8, 12, 13, 17, 18- Octaethyl-porphinato] vanadyl, (OEP)V=O, adsorbed on the hypotenuse face of a glass prism. Rotational intensity patterns are showed by plotting the second harmonic intensity as a function of the incident polarization angle of the fundamental wave, at a fixed angle of incidence. Evaluation of these patterns by Fourier analysis allowed the determination of the second order susceptibilities components of the adsorbed layers. Assuming a delta distribution function, the mean orientation angles from normal to the surface plane, were obtained for different solution concentrations. Our results indicate an abrupt change in the angle for two concentration ranges