The magnetic parallelizer as an optical element for Auger electrons: Further characterization

The resolution and efficiency of electron energy analyzers for Auger or photoelectron spectroscopy is often determined by the quality of the optical element between the electron-emitting sample and the spectrometer. The problems in designing a magnetic parallelizer as such an element is discussed in terms of the area in phase space occupied by the electron beam. Monitoring this area as a function of position along the beam path shows that magnetic monopole fields have very useful optical properties. Careful combination of a monopole field with a constant field can keep the increase of the occupied phase space of 1000 eV electrons to within 10% of the theoretical minimum under adiabatic conditions. It is shown that a good parallelizer can be designed using a magnetic circuit with one unconnected floating pole piece. This concept combines good optical properties for a primary electron beam with excellent parallelization of the Auger electrons. (orig.)