Effects of polarization of infrared spectra collected in reflection at grazing incidence

Abstract

Reflection-absorption infrared spectrometry (RAIRS) of an ultrathin organic film (25 nm thick) on a metallized slide as a function of incident beam polarization has shown that an intensity enhancement factor of ca. 2 can be achieved. It is demonstrated that such an effect may be quantitatively predicted and that the enhancement factor depends on the band intensity (absorbance). Thus the use of an unpolarized infrared beam in RAIRS experiments leads to spectral distortion, which should always be avoided by employing a p-polarized infrared beam.