Spectroscopy of Molecular Monolayers by Resonant Second-Harmonic Generation

Abstract

Spectra of the ${S}_{0}\ensuremath{\rightarrow}{S}_{2}$ electronic transition of rhodamine dyes adsorbed at submonolayer coverages on a fused silica substrate have been obtained by resonant second-harmonic generation. Polarization dependences of the second-harmonic signal have been studied and are used in the construction of a model for the orientation of the adsorbates. A value for the molecular second-order nonlinear polarizability at resonance is deduced.