Model for reflectance anisotropy spectra of molecular layered systems

We present a theoretical study based on the local field interaction for the reflectance anisotropy spectra of organic molecular layers. Each layer is formed by an ordered two-dimensional array of polarizable organic molecules that respond to the local electric field like point-like harmonic oscillators. We concentrate on the morphological characteristics of the layers and its effect on the spectra, showing that the reorientation of the molecules from layer to layer, as the system is assembled, gives rise to a line shape of the spectra that goes from peak-like to derivative-like. Our spectra shows good qualitative agreement with experimental results of a layered system of metalloporphyrin octaesters molecules deposited onto an isotropic gold substrate by the Langmuir-Schaefer technique.