Low pressure discharge lamps containing mercury, cadmium or zinc.
Some spectrophotometers contain lamp housings for these lamps (Hg, Cd, Zn). Where this facility is
provided, wavelength checks can be made very conveniently by operating the discharge lamp and
rotating the monochromator to isolate the emitted spectral lines. For this and all wavelength calibrations
the minimum slit width should be used. The mercury lamp has the advantage that its emission
spectrum contains several lines over a reasonable range of wavelength. Wavelengths in air of
prominent spectral lines of these elements are listed in Table 3.