Light scattering of thin dielectric films: self-assembled monolayers on the surface of polycrystalline gold

Abstract

The peculiarities of interfacial structure of self-assembled layer of dodecanthiol on the gold surface determined by quasi-elastic light scattering were employed to probe the lateral distribution and preferred orientation of the thiol molecules within the monolayer. The analysis of Angle Resolved Scattering in the framework of theoretical description involving both scattering on surface roughness and nonuniformities of dielectric permittivity of the near- surface layer allowed to establish the presence of correlation in counterphase between distribution of the thickness of the thiol coating and the relief of the gold surface. The distribution of the scatters in the thiol film is similar to that in as-deposited film of gold that is evidence of the dominant role of the structure of the relief of gold film in formation of the thiol layers. The formation of thiol layer on surface of polycrystalline gold is a complex process including adsorption, local self-assembly and surface-induced distortion of organized structure primary in the region of surface cavities. This study confirmed the utility of the proposed approach based on the nondestructive analysis of organized interfacial layers for detection spatial distribution and chemical functionality of self-assembled monolayers in practical sensing devices.