Synchrotron infrared microspectroscopy reveals localized heterogeneities in an organically modified silicate film

Abstract

High spatial resolution, 7 μm×7 μm confocal image plane masking, and 1 μm step size mapping were used to image small areas of an organically modified silicate (ORMOSIL) film. The film was prepared by the sol–gel process from separately hydrolyzed isobutyltrimethoxysilane and tetraethoxysilane sols that were mixed just prior to being spin cast onto a polished silicon substrate. Detailed mapping was performed in a reflection absorption mode with an infrared microspectrometer at beamline U10B of the National Synchrotron Light Source of Brookhaven National Laboratory. The main objective of this study was to characterize the spatial distribution of organic (i.e. butyl) components within the film. Functional group maps of each film region were produced from the peak areas of the CH, OH, and SiO stretching bands. The organic content (relative to total silicate) was obtained by ratioing the peak areas of the CH and SiO absorption bands. Functional group maps of a relatively large region ( 230 μm×230 μm) with a 10 μm×10 μm mask size and a 10 μm step size reveal heterogeneity on a larger scale. These data demonstrate the utility of IR imaging in the study of ORMOSIL film chemical heterogeneity.