Extraction of quantitative information from large sets of sequential time-series spectra (two-dimensional, 2D, data) using a curve-fitting procedure is investigated. The difference between any experimental
spectrum and any curve-fitted spectrum is constructed in a least-squares manner and the Pearson VII model is selected as the general band-shape function for the infrared absorbance spectra. The starting
point for the curve-fitting procedure is a 2D peak map. Next, an interior spectrum from the 2D array is chosen, initial guesses of the band parameters are provided by an initialization scheme, and curve
fitting is performed. Once optimal values of the Pearson VII model band parameters are obtained from the starting spectrum in the 2D array, these are then used as reasonable and judicious initial guesses
for subsequent curve fitting of the neighboring spectra in the time series. This increases computational efficiency enormously. By adjusting the band center positions for moving bands, and re-optimizing
each subsequent curve-fitting calculation to account for changing band shapes, the entire 2D array is rapidly and efficiently modeled. A 2D experimental spectroscopic time-series array from a homogeneous
rhodium-catalyzed hydroformylation reaction was successfully curve fitted in this manner. The procedure holds considerable promise for the curve fitting of massive time-series spectroscopic data, such as
that arising from on-line process monitoring of expensive value-added specialty chemical and pharmaceutical syntheses.
Department of Chemical and Environmental Engineering, 4 Engineering Drive 4, National University of Singapore, Singapore 119260
Publication date: March 1, 2003
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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)