Electron spectrometer

An electron spectrometer is a spectrometer for the energy and direction analysis of electrons . It usually consists of an analyzer that lets electrons of a certain energy (English pass energy ) and a certain direction of travel through, as well as a detector .

The analyzer usually has an entry slit through which the electrons enter and an exit slit through which they reach the detector. When using spatially resolving detectors, there is often no need for an exit slit. The deflection of electrons in an electric or magnetic field is used to filter the electron energy . Only the electrons of a certain kinetic energy (the so-called pass energy), which hit the entrance slit at a certain angular range, can then pass both the entrance and the exit slit of this monochromator . The pass energy of the monochromator is regulated by changing the electrical voltage on the capacitor so that electrons with a different kinetic energy reach the detector. With this arrangement, the electron count rate is determined for various pass energies and plotted as a spectrum . Possible geometries for an electrostatic analyzer are e.g. B. plate capacitor , cylinder capacitor and spherical capacitor , each with inlet and outlet openings.

As a detector often comes a secondary electron multiplier is used, it is often referred to as electron multiplier executed (English chan eltron). The gain is sufficient here to count individual electrons. Mostly spatially resolving detectors are used in modern electron spectrometers. These consist of a microchannel plate (English micro channel plate MCP) and a fluorescent screen . The resulting image of the spectrum is then recorded with a CCD and processed into a spectrum.