Linear prediction algorithm in coherent Raman spectroscopy

Abstract

The aim of this thesis was to study the LOMEP line narrowing algorithm detailed by Kaup- pinen et al. 2001a and its applicability on CARS spectra. Experimental CARS spectra exhibit features such as varying spectral line widths and shapes which are assumed constant for each constituent line shape in the LOMEP algorithm. The results of the line narrowing showed convergence on the correct line positions for the simulated spectra except when line shapes were positioned close to each other. The heights of the line shapes did not behave well during the LOMEP algorithm and showed erratic results. The results were found to be stable within a range of assumed FWHM values but choosing the other parameter values for the algorithm was found to be problematic. The Voigt line shape was found to be more erratic compared to the Lorentzian line shape. In the case of the sucrose spectrum, the algorithm produced similar results as in the reference material used but with additional line shape positions identified.