Electrostatic lens, electrons acceleration/retardation

In order to demonstrate the convenient properties of lenses combined with an electrostatic energy analyser, three examples will be discussed first the important case in which an acceleration/retardation lens is placed in front of the analyser which allows an operation mode with a constant pass energy in the analyser second the case in which increased acceptance angles are used, which is important for coincidence experiments and third the case in which 0 eV electrons are handled and analysed with high resolution and high acceptance. 

An experimental set-up using a lens system for the acceleration/retardation of the electrons in conjunction with an electrostatic analyser is shown in Fig. 4.32. The electron spectrometer is a spherical analyser with a mean radius R0 of 101.6 mm combined with a three-aperture zoom lens at the entrance and the exit. Only the purpose and the characteristic properties of the entrance lens will be... 

Modifications to Electron Beam System. The retarding potential field was introduced into our vector scan system by attaching a O-to-20 KV, 2 mAmp external power supply to the wafer holder. This is shown diagrammatically in Figure 2. Whereas the wafer is at ground potential in the standard system, in our modified system the net potential at the wafer can vary from 0 to 20 KV. Thus, the electrons are accelerated down the column at a standard operating potential, exit the final lens and are retarded by the variable electrostatic field near the wafer plane. 

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