The infrared spectrum of an adsorbed monolayer of octadecyltrichlorosilane (OTS) on mica has been recorded in the transmission mode. The problem of interference fringes has been reduced by cleaving mica to thicknesses of ~1 μm so that the period of the fringes is much greater than the bandwidth of the bands due to adsorbed molecules. In addition, mica of this thickness has the added advantage of being transparent below 1200 cm<sup>−1</sup>, which allows observation of bands arising from adsorbed species in this spectral region. An improvement in signal-to-noise ratio can be obtained by placing the thin mica sheets in series. We have also demonstrated that Attenuated Total Reflection (ATR) can be used to measure spectra of material deposited on the exposed surface of a thin mica sheet in contact with the ATR crystal.
D. A. Guzonas, M. L. Hair, and C. P. Tripp, "Infrared Spectra of Monolayers Adsorbed on Mica," Appl. Spectrosc. 44, 290-293 (1990)