[ToC]

 

H. N. Southworth, Introduction to Modern Microscopy, Wykham, 1975

BALL MODEL OF THE SURFACE OF A FIELD-ION OR FIELD EMISSION SPECIMEN, (A) SHOWING THE REGULAR TERRACED STRUCTURE, WITH VARIOUS FACETS INDEXED CRYSTALLOGRAPHICALLY; (B) WITH THE MOST PROTRUDING ATOMS ILLUMINATED

Each facet on the tip surface is made up of a series of ledges and steps, and it is the atoms at the edges of the leges which protrude the most from the surface, and hence experience the highest field. Fig. 6.13 b [bottom] shows the same model as in fig. 6.13 a [top] but with these most protruding atoms highlighted.