Monochromators

An improvement over cutoff reflectors in terms of lowering the background of the recorded spectra is the use of monochromatic excitation beam. The monochromatization of the X-rays can be realized neither by a low pass filter, not by a foil filter but only by a monochromator: a natural crystal or a synthetic multilayer structure. Both types of monochromators are used as Bragg reflectors, with a definite energy band selected at a particular angle of reflection. This angle should be set in accord to the Bragg's Law (2dsinθ = nλ). For a chosen photon energy E in keV the angle can be calculated by: