Computational methods are proposed and tested that enhance the spatial resolution of infrared microspectroscopic data collected from multilayer polymeric materials film structures. The data collected from such a structure with the use of an infrared microspectroscopic system are diffraction
limited at approximately 10 μm (however, diffraction limits are wavelength dependent); therefore, layers of thickness less than approximately 10 μm give rise to spectra that are mixtures of spectra from surrounding layers. Some authors have even pointed out that this could be the case
for areas sampled that were much greater than 10 μm. Factor analysis of the data matrix can reveal the number of spectrally different layers that are present, and the eigenvectors will give an abstract representation of the positional and wavelength information. An algorithm has been devised
that uses layer boundary positions, aperture width, and aperture step size to model the positional information from such an experiment. The boundary layer positions may be used as adjustable parameters in a nonlinear optimization problem that fits the positional model to the abstract factor
analysis positional data. This algorithm is applied to simulated and real data. Simulation results indicate superior performance in comparison with spectral matching to the raw data, and analysis of real data indicates consistent results as well as the ability to resolve unique spectral features
when compared with results from more painstaking data collection experiments.
Analytical Sciences Laboratory, 1897D Building, The Dow Chemical Company, Midland, Michigan 48667
Publication date: May 1, 1993
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The Society publishes the internationally recognized, peer reviewed journal, Applied Spectroscopy, which is available both in print and online. Subscriptions are included with membership or can be purchased by institutional or corporate organizations. Abstracts may be viewed free of charge. Previously published as Bulletin (Society for Applied Spectroscopy)