Electron Monochromator Design

Abstract

A study has been made of all the known factors which limit the performance of high resolution (0.07 to 0.01 eV FWHM) monochromators. These limiting factors have been incorporated into design equations for the optimum (maximum current output) monochromator. The conclusions are tested by performance measurements on a prototype instrument. The results require the introduction into the design equation of a new limiting factor, an anomalous energy spread in dense electron beams, which is empirically determined.

Electron monochromator-mass spectrometer instrument for negative ion analysis of electronegative compounds

“…This instrument produced homogeneous electron beams with energy spreads of <0.005 eV, but no improvement in beam brightness. In all of these devices, the intensities of the electron beams produced were very weak, and efforts to increase beam brightness could only be achieved at the expense of energy bandwidths that were much greater than those that would have been predicted on the basis of the filament temperatures (40). Electrostatic analyzers are notorious for unpredictable performance when gases introduced into the target chamber modify the contact potentials of the electron optic elements (41).…”

Invited Article: An improved double-toroidal spectrometer for gas phase (e,2e) studies

“…Historically, the most commonly used momentumdispersive analyzers have been based around electrodes of cylindrical 21,22 or spherical 23,24 geometry. Both of these geometries are, in fact, topologically related, with cylindrical and spherical surfaces representing limiting cases of the whole family of toroidal surfaces.…”

Photoelectron Diffraction and Synchrotron Radiation

“…In order to monitor the photoelectron flux as a function of emission direction relative to the sample crystal axes, some angle-resolving energy analyzer -usually a hemispherical-sector analyzer [11] -is either mounted at a fixed position relative to the exciting photon source while the crystal is rotated, or alternatively a smaller analyzer is moved above a fixed crystal. The first solution has usually the advantage of higher sensitivity, while the second permits also to exploit the dependence of diffraction effects on the photon polarization, particularly if the crystal can still be rotated [12].…”