Tackling detector non-linearity in Fourier transform infrared spectroscopy

DTGS detectors are commonly fitted to standard FT-IR spectrometers and their linear response to photon flux is excellent. These detectors are not particularly sensitive or fast. In well-maintained and leak-free systems the concentration of the breakdown products is very small. However, certain of these products are highly toxic and chemically aggressive leading to the possibility of damage to the electrical equipment. The studies involve the quantitative determination of breakdown products. Although the concentrations of the breakdown products were in the ppm range, the large differences in concentrations measured forced researchers to employ two gas cells of different pathlength. By comparing spectra taken with both detectors it was clear researchers were suffering from non-linearities in the response of the spectrometer when using the MCT detector.