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Proceedings Paper

Surface infrared spectroscopy using a dual-channel polarization-modulation spectrometer
Author(s): Matthew J. Smith; Robert Dueval; Robert M. Corn
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Paper Abstract

The sensitivity of an FT-IR spectrometer for measuring monolayers and other thin films can be enhanced if one takes advantage of the surface selection rule to reduce the dynamic range of the experiment. This is accomplished in polarization modulation infrared reflection-absorption (PM-IRRAS) by rapid modulation (74 KHz) of the linear polarization of the incident light , and subsequent demodulation of the detector signal. PM-IRRAS yields a differential signal which contains only the surface information. This differential signal is usually ratioed against the total reflectance signal to yield the spectrum of interest. Normally, two sequential measurements are required. First, the differential signal is acquired, then the total reflectance measurement is made. However, a better method is to use the dual channel approach first described by Buffeteau, et. al.1 The principal advantage of this method is that all isotropic (i.e. atmospheric and nonsurface) absorptions are perfectly ratioed.

Paper Details

Date Published: 1 March 1992
PDF: 2 pages
Proc. SPIE 1575, 8th Intl Conf on Fourier Transform Spectroscopy, (1 March 1992); doi: 10.1117/12.56368
Show Author Affiliations
Matthew J. Smith, Nicolet Instrument Corp. (United States)
Robert Dueval, Univ. of Wisconsin/Madison (United States)
Robert M. Corn, Univ. of Wisconsin/Madison (United States)


Published in SPIE Proceedings Vol. 1575:
8th Intl Conf on Fourier Transform Spectroscopy

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