Improvement of the Limiting Thickness of the Measurable Surface Layer on Polymer Films Using Fourier Transform Infrared Attenuated Total Reflection Spectroscopy with the Use of Silver Island Films

Abstract

Improvement in the detection limit of the surface layer on polymer films has been demonstrated with the use of Ag films under Kretschmann's attenuated total reflection (ATR) geometry. A remarkable absorption enhancement for 2.5-nm-thick polydimethylsiloxane (PDMS) or for 4.0-nm-thick polycarbonate (PC) coated on polyethyleneterephthalate (PET) films was observed. The magnitude of the enhancement factor is 10 for PDMS and 2 for PC compared with results for the conventional ATR method. In the case of PDMS, the limiting thickness of the measurable surface layer is about 0.5 nm with the use of the spectral subtraction technique. The correlation between the difference in the enhancement factor and the enhancement mechanism is also discussed.