An electron energy analyser with a retarding potential filter and a new differentiating system

The design and construction of a simple, high resolution energy analyser with a new differentiating system is described in detail. An einzel lens developed by Brack was used for producing retarding potential. A small beam current of 10^-15 A was measured by the use of a scintillator and a photomultiplier. In order to differentiate energy distribution curves and to improve the signal to noise ratio an A. C. modulation circuit with a phase-sensitive detector was used. The energy profile of a 26 keV electron beam and the characteristic energy loss spectrum of aluminium were measured to examine the characteristics of the analyser. The energy resolution obtained at 26 keV was 0.5 eV. This resolution was limited not by the resolving power of the electron filter but by the primary beam energy spread.