High-resolution thermionic cathode scanning transmission electron microscope

A new scanning transmission electron microscope has been built which uses a lanthanum hexaboride thermal cathode electron gun. Initial results indicate a beam diameter of 5 Å and point-to-point resolution of 7 Å. The vacuum level in the instrument is similar to that of standard commercially available electron microscopes. A comparison of the performance of tungsten hairpin, lanthanum hexaboride, and field emission cathodes for scanning transmission electron microscopy is given. © 1973 American Institute of Physics.