DECOMP: A Fourier Transfom Spectra Decomposition Program

Abstract

Current techniques for processing high resolution Fourier transform spectra revolve around interactive graphical display of the spectrum on a computer. The DECOMP spectrum decomposition program is designed explicitly for the reduction of Fourier transform spectra and focuses on reducing a spectrum into a list of line parameters. Basic methods of spectrum manipulation will be demonstrated and a IBM PC - compatible computer will be available for hands-on demonstrations of the process of spectrum analysis. Figures 1 and 2 illustrate the process of background subtraction: in Figure 1 a low resolution spectrum is generated by binning the high resolution spectrum and beneath the spectrum is a background correction function generated by creating a low resolution "minima" spectrum and smoothing the spectrum. The results of the background correction are given in Figure 2. Figure 3 illustrates a common problem in Fourier transform spectroscopy: the finite length of the interferogram introduces "ringing" into the spectrum. Using a filtered fitting routine in DECOMP the ringing can be effectively removed yielding a spectrum illustrated in Figure 4, in which several new spectral features that had been hidden beneath the ringing. An example of the atlas plots that can be generated using DECOMP is given in Figure 5.