Editing Field electron emission (section)

=== Atomically sharp emitters ===
Nowadays it is possible to prepare very sharp emitters, including emitters that end in a single atom. In this case, electron emission comes from an area about twice the crystallographic size of a single atom. This was demonstrated by comparing FEM and [[field ion microscope]] (FIM) images of the emitter.<ref name=Fi88>{{cite journal|doi=10.1088/0031-8949/38/2/029|title=Point source for ions and electrons|year=1988|last1=Fink|first1=Hans-Werner|journal=Physica Scripta|volume=38|pages=260–263|bibcode = 1988PhyS...38..260F|issue=2 |s2cid=250806259 }}</ref> Single-atom-apex Mueller emitters also have relevance to the [[scanning probe microscopy]] and [[scanning Helium Ion Microscope|helium scanning ion microscopy]] (He SIM).<ref name=WNB06>{{cite journal|doi=10.1116/1.2357967|title=Helium ion microscope: A new tool for nanoscale microscopy and metrology|year=2006|last1=Ward|first1=B. W.|last2=Notte|first2=John A.|last3=Economou|first3=N. P.|s2cid=55043024|journal=Journal of Vacuum Science and Technology B|volume=24|page=2871|bibcode = 2006JVSTB..24.2871W|issue=6 }}</ref> Techniques for preparing them have been under investigation for many years.<ref name=Fi88/><ref name=BGP96>{{cite journal|doi=10.1016/S1076-5670(08)70156-3|title=Electron Field Emission from Atom-Sources: Fabrication, Properties, and Applications of Nanotips|year=1996|last1=Binh|first1=Vu Thien|last2=Garcia|first2=N.|last3=Purcell|first3=S.T.|volume=95|pages=63–153|journal=Advances in Imaging and Electron Physics|bibcode=1996AdIEP..9582b83B |isbn=9780120147373}}</ref> A related important recent advance has been the development (for use in the He SIM) of an automated technique for restoring a three-atom ("trimer") apex to its original state, if the trimer breaks up.<ref name=WNB06/>