The generalized two-dimensional (2D) correlation analysis was applied to depth-profiling confocal Raman microspectroscopy in order to characterize spatial distributions of multilayer
polymer films. First, depth-dependent micro-Raman spectra of a multilayer
film were measured non-destructively and then the depth-correlated synchronous and asynchronous 2D Raman spectra were calculated from those spectra according to the generalized 2D correlation formalism. Next, the materials of the component layers of the film were determined from the cross peaks on the correlation squares that could be constructed in the synchronous 2D correlation spectrum. Finally, the depth sequence of the layers in the film was determined from the cross peaks on the asynchronous correlation squares corresponding to the synchronous ones.