Comments on ``Grain boundary contrast in field-ion microscope images''. II

Abstract
A recent paper by French and Bishop has discussed the field‐ion contrast from a particular grain boundary configuration as a function of increasing angular misorientation, the images being constructed by computer simulation. Although their boundary configuration was pure tilt about [110], the resulting surface contrast displays apparent tilt and twist character because of the oblique surface section of the emitter tip chosen to contain the boundary trace. The present paper aims to distinguish the contrast events occurring in such images as a function of this apparent tilt and twist character and to quantify the expected contrast in terms of the ``ring‐matching'' contrast theory proposed by the present authors.