Detection of organosilanes with surface enhanced infrared spectroscopy

Abstract

DETECTION OF ORGANOSILANES WITH SURFACE ENHANCED INFRARED SPECTROSCOPY by Anh Duong Infrared transmission spectra of 1 nm thick organic films were studied with and without the aid of a 5 nm thick Au island film enhancement layer. It is estimated that absorbance intensities for these molecules were about 100 to 200 times higher when they were deposited onto Au films. When the Au film is annealed at 250°C the absorbance of these molecules decreased. The smaller islands in the un-annealed Au films were more active enhancers of the IR absorption. Given the approximate concentration of the molecules within the molecular film and assuming that the extinction coefficients are the same in solution and in the film, the apparent thickness can be calculated. This thickness exceeds the measured thickness by 10 300 times. Even accounting for some additional adsorbed material using a simple model of the surface, this thickness is greater 5-150 times, than the true thickness.