Dynamic Range Problems in Fourier Transform IR and Far-IR Spectroscopy

Abstract

The exploitation of both the multiplex and the aperture advantage in Fourier transform IR and far-IR spectroscopy may lead to nonlinear detector response or saturation of the A/D converter. This limitation of the dynamic range only concerns the center-burst peak of the interferogram function. After the Fourier transformation, the respective distortion in the frequency or—better—wavenumber domain is completely delocalized. Erroneous intensity contributions are, in principle, present in all parts of the spectrum under consideration. Thus, it is not easy to diagnose the effect of a limited dynamic range. Practical procedures for the recognition and elimination of the respective artifacts in the spectrum are, therefore, suggested; they are to be used in conjunction with the application of the IR transmission technique to surface studies of high-surface-area SiO2.