Model 10-420 Toroidal Monochromator
The PHI 5600 has two sources for X-ray generation. In , in both cases rays are produced by bombarding a metallic anode (Al or Mg) with high-energy electrons. The energy of the emitted X-rays depends on the anode material and beam intensity depends on the electron current striking the anode and its energy. The X-rays produced have a wide range of frequencies composed of a combination of bremsstralhung radiation and atomic X-rays from the material used for the anode.
To produce single energy X-rays, the 10-420 toroidal monochromator uses a beam of electrons strike a water-cooled, aluminium anode and produce a beam of Al K-alpha radiation (1486.6 eV). This beam strikes the quartz crystal planes at an angle and are reflected at the same angle by Bragg diffraction; X-rays with the appropriate wavelength interfere constructively producing a monochromatic beam of X-rays (see the see diagram in the figure). The size of the X-ray spot at the sample is equal to the size of the electron beam spot on the anode; the analysis area can be controlled by the electron beam spot size.
The quartz crystal is usually bent with radii of curvature different in each direction (toroidally bent) to focus the X-rays (see the focusing X-ray monochromator in the figure).