A low-energy electron diffractometer

Abstract

The invention provides a low-energy electron diffractometer, comprising: an electron generating device, a charged particle optical system, a sample and a two-dimensional image electron detector. The electron generating device is used to generate electrons; the charged particle optical system includes a magnetic field and a non-axisymmetric electric lens group, the magnetic field is used to separate the motion tracks of the incident and outgoing charged particles, and realize the deflection of the direction of motion of the charged particles; the non-axisymmetric electric lens group It is used to compensate the asymmetry of the magnetic field optical characteristics in the vertical and parallel magnetic field directions, reduce the aberration, and make the charged particle beam image simultaneously on the image plane in two directions along the vertical magnetic field direction and the parallel magnetic field. The low-energy electron diffractometer of the present invention can realize the separation of incident and outgoing charged particle orbits, thereby avoiding the geometrical configuration difficulties of each component, realizing low-energy electron diffraction measurement without electron gun shadow, and making time-resolved low-energy electron diffraction measurement more convenient.

Description

technical field [0001] The invention relates to the fields of charged particle optics and low-energy electron diffraction, in particular to a low-energy electron diffractometer. Background technique [0002] Electron lens systems have been used in a wide range of applications, ranging from picture tubes in the first generation of televisions to scientific instruments such as electron energy analyzers. Magnetic fields and magnetic lens systems play an important role in the imaging of high-energy electron and ion beams. The time-reversal antisymmetry of magnetic fields to moving charged particles has been applied to separate the orbits of incoming and outgoing particles. Magnetic fields have different optical properties for charged particles in directions perpendicular to and parallel to the magnetic field. In the direction of the vertical magnetic field, due to the effect of the Loren magnetic force, the charged particles emitted from the same point will converge again afte...

AI Technical Summary

Problems solved by technology

However, the electron gun and detector of the current low-energy electron diffractometer are located on the front of the sample, and the laser beam can only be incident from the side of the needle tip, which is not conducive to the generation of high-quality pulsed electrons; at the same time, although the field emission electron gun has a simple structure, good monochromaticity and The advantages of easy generation of electron pulses, due to the high price of large-scale high-sensitivity two-dimensional detectors (such as multi-channel plates) and the small emission current of field emission electron guns, it is not easy to be applied in conventional low-energy electron diffractometers

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