Norton-Beer medium

There are other apodization functions in use besides the Norton-Beer and the Happ-Genzel. These functions have not been tested as thoroughly however, it has been noted by the authors that the Blackman-Harris and Blackman apodization functions (Section 2.4) are considerably broader than the Norton-Beer medium or Happ-Genzel apodization functions. It is expected that these functions will not adhere to Beer s law as well as the Norton-Beer medium function. 

It is possible to purchase variable-pathlength liquid transmission cells, which commonly have a pathlength that can be varied between 5 pm and 5 mm. A suitable sample must be chosen, preferably a neat solvent that has relatively wide peaks, the resolution of the spectrometer must be set so that the resolution parameter, p, is no greater than 0.5, and a Norton-Beer medium apodization function should be applied. A series of measurements at increasing pathlengths should yield a linear Lambert plot if the instrument is functioning correctly. Some instruments will exhibit linear Lambert plots up to 4 AU however, this is unusual, and an acceptable... 

Figure 5.3. Various apodization functions (left) and the instrumental lineshape produced by them (right) (a) boxcar truncation (b) triangular (c) trapezoidal (d) Norton-Beer weak, medium, and strong (e) Happ-Gen-zel (f) Blackman-Harris 3-term and 4-term. The maximum retardation is set to / = 1. In the Fourier transform the FWHH of the main lobe is indicated.

Figure 2.10. (a) Weak, medium, and strong apodization functions proposed by Norton and Beer (b) corresponding lineshape functions with the sine function shown for reference. 

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