Method for the simultaneous determination of line strengths and collisional widths from high-resolution Fourier...

The considerable increase in high-resolution Fourier transform spectra has led to a practical method of deriving individual line parameters from Fourier data. This method concerns in the main those spectra exhibiting moderately dense structure, so that spectral analysis can be carried out in pressure conditions where collisional broadening dominates: (1) For any line under study, the strength and width values can be determined simultaneously from the same spectrum. (2) Instrumental distortions can be reduced by pressurizing the gas sufficiently. In the present case the relevant corrections do not exceed 3%, in a few cases 5%. (3) Thus, from the analytical expression of the apodized apparatus function, it is possible by means of a convolution calculation to draw up a series of tabulations. These give the true linewidth and the dimensionless quantity K(sigma(0))l, respectively, as functions of the width and maximum transmission of the observed contour. The calculation has been extended to the case of doublets of the same intensities, widths, and known spacing. The method has been tested by investigating a few self-broadened lines in the 12 degrees 0-00 degrees 0 transition of N(2)O and some nitrogen-broadened lines in the fundamental band of NO recorded at the laboratory by G. Guelachvili.