Boersch effect
The Boersch effect (after the Berlin physicist Hans Boersch , who discovered the phenomenon in 1948 at the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig ) is an anomalous energy distribution in intense electron beams . The effect limits the resolution (energy and spatial resolution ) of electron microscopes and in electron beam lithography .
description
When exiting a cathode , the electrons have different speeds due to the Maxwell-Boltzmann distribution . This velocity distribution widens further in front of the cathode due to the formation of space charge clouds , which result in an electrostatic repulsion of the electrons from one another. The Boersch effect is the difference between the actual and Maxwell's velocity distribution, which is in the order of about one electron volt. The effect is particularly pronounced at low beam voltage and high beam current.
literature
- J. Schubert: Physical Effects. 2nd edition, Physik-Verlag, 1984, ISBN 3-87664-082-2 , p. 10.
- L. Bergmann, H. Niederig, C. Schaefer: Optics: Wave and particle optics. Volume 3, Verlag Walter de Gruyter, 2004, ISBN 3-11-017081-7 , p. 1120 ( limited preview in the Google book search)
Web links
Individual evidence
- ↑ University of Tübingen: Estimating calculation of the Boersch effect in an electron monochromator. ( Page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. Retrieved December 31, 2010
