Wavelength dependence detector absorption

It is clear that the spatial resolution (the separation between the two points required for them to be resolved, i.e. 2r) is not merely dividing the number of detector pixels by the width of the image. The spatial resolution in transmission FTIR imaging should be in the order of 10-30 pm depending on the wavelength of the absorption band used. 

Each reciprocal lattice point is stimulated by some wavelength within the experimental bandwidth. A variety of wavelength-dependent factors affect the measured structure amplitude. These factors include the SR spectral profile, the effect of optical elements, sample scattering efficiencies, absorption of components in the beam and detector response. 

The ELSD has a more uniform response to analytes than a UV absorption detector, whose response factors for different compounds vary widely and are wavelength dependent, and which gives no response at all to many compounds as shown in Fig. 13.9(2). 

Diode array detector (DAD) DAD is used to measure molecular absorption of at a certain ultraviolet-visible (UV/Vis) wavelength. The amount of light absorbed will depend on the amount of a particular compound that is passing through the beam at the time and the absorbance of that compound at a particular UV wavelength. The difference between a DAD and a fixed wavelength UV detector is that a DAD can scan across a predetermined wavelength. 

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