Fourier transform-based deconvolution techniques for resolution of overlapping bands in x-ray photoelectron and fourier-transform infrared spectra of bisphenol-a-polycarbonate/dimethyl siloxane block copolymers

Abstract

A series of bisphenol-A-polycarbonate/poly(dimethylsiloxane) (BPAC/DMS) block copolymers is studied by x-ray photoelectron (x.p.s.) and Fourier-transform infrared (F.t.i.r.) spectroscopies. Previous quantitative results, obtained without resolution enhancement, provided calibration of the signal-processing techniques used. A Van Cittert technique for x.p.s. is evaluated for the deconvolution of the carbon 1 s core photoelectron spectrum, and self-deconvolution by Fourier methods is evaluated for the overlapping Si-CH 3 and aromatic C—O stretch bands at 1261 and 1228 cm -1, respectively, in the i.r. spectrum. These features can be utilized in quantitative analysis of the surface and bulk of the BPAC/DMS copolymers. The ability of deconvolution techniques to narrow the bands artificially so as to resolve complex spectral envelopes, while retaining the quantitative data is discussed. The studies illustrate the ability of modern signal processing techniques to extract exact complex data from spectroscopic results, and allow quantitative evaluation without standards for complex polymer systems.