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In SEM, in order to 'focus' the electron beam, an aperture is used (which usually is metal); what happens to the metal after so many electron hits the metal constantly?

since metals are usually are saturated, and its in vacuum; its highly unlikely no chemical reaction happens, but does it make any kind of change to the metal?

based on my assumption, if there is no chemical reaction, there should be no chemical change or physical change, but I hope someone could shed a light on this for me.

Thanks a million!

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  • $\begingroup$ The apertures are conductive, and tied to ground. The main chemical reactions are various junk on the aperture (water, hydrocarbons, ...) that are adsorbed on the surface. $\endgroup$ – Jon Custer Jun 26 at 17:36
  • $\begingroup$ @JonCuster: thank you for your explanation. from this 1) there is certain amount, if not large amount, of electrons are getting wasted inevitably 2) we might need to replace the column periodically. can I understand like that? $\endgroup$ – Dil Azat Jun 27 at 15:45
  • $\begingroup$ Apertures are, indeed, a maintenance item. $\endgroup$ – Jon Custer Jun 27 at 16:03

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