A Polarization Modulation Infrared Reflection Technique Applied to Study of Thin Films on Metal and Semiconductor Surfaces

An infrared grating spectrophotometer newly designed for polarization modulation measurements is described. The spectrometer can be characterized by the grating monochromator inclined by 45° with respect to the planes of polarized incident beams. This polarization modulation apparatus allowed us to measure a single monolayer of stearic acid formed on an Ag mirror in a good S/N ratio. At the same time the resolution of the obtained spectrum was sufficient for discriminating among different absorption bands due to the C-H stretching vibrations. The apparatus was employed to characterize an anisotropic structure of cadmium arachidate monolayers built up on Cu substrate surfaces. By means of the same technique, the infrared spectrum of a polyvinylacetate film 10 nm thick on Si could be obtained by using the optimum angle of incidence.