The use of an intermediate barrier layer to vary the penetration depth in an ATR experiment is investigated. Both theoretical and experimental results suggest that this method may be useful in probing concentration profiles away from the interface, particularly in the case of thin films, where variable-angle methods have limitations. Application of this technique in the study of poly(methylmethacrylate)/poly(dimethylsiloxane) (PMMA/PDMS) graft copolymers deposited onto a copper oxide surface indicates a preferential presence of the siloxane component at the oxide interface, a concentration which tends to decrease with increasing distance into the bulk of the sample film.
Eva Marand and L. Mike Smartt, "ATR Spectroscopic Study of PMMA/PDMS Graft Copolymers Using a Barrier Layer Method," Appl. Spectrosc. 49, 513-519 (1995)