Computer-Replicated Spectrograms By Ensemble Averaging and Normalization

High resolution absorption bands, as produced by a tunable diode laser, are superimposed on a background that reflects both the variation of the laser-output power with frequency and the specificity of the spectrometer used to filter out unwanted cavity modes. Gross distortions of the absorption bands from these combined effects make the extraction of characteristic line data extremely tedious or error prone. To address these features, I measured high resolution infrared spectra in the 8.7 microns region using a tunable diode lasers spectrometer where the latter is interfaced -using the Labwindows' MC-MIO-16 interface board - to the IBM Model 70 PS/2 computer. The replicated computer enhanced spectrograms are free of random fluctuation noises that typifies analog chart recorder outputs. The production of the computer-replicated spectrograms occurs from a software program called the "horter.” I have addressed the problem of normalization of the spectrograms, using a second computer program. The overall outcome is a computer- replicated spectrogram having reduced spectra band distortions. These two improvements have implications for increasing the measurable of the line parameters, halfwidths, pressure broadening coefficients, and the line intensities. Measurements have been made for such gases as N2O, and SO2.