It has been previously reported that the cleavage of singlehyphen;crystal LiF produces intense, longhyphen;lasting electron emission persisting several minutes after fracture (called posthyphen;emission). We find that this contrasts dramatically with the weak, rapidly decaying emission accompanying LiF fracture in threehyphen;point bend or tension. We examine the dependence of intensity and duration of the electron emission produced by LiF cleavage on the interaction of the cleavage blade with the LiF crystal. We show that the damaged region where the cleavage blade and crystal come into contact is by far the major source of the posthyphen;emission. Macroscopic particles (lsquo;lsquo;ejectarsquo;rsquo;) from the damaged region which frequently cling to the fracture surface are also shown to be highly emissive. In contrast, the lsquo;lsquo;untouchedrsquo;rsquo; cleavage surface emits little, if any, posthyphen;emission (on the time scale of several seconds). We propose that the high intensity emission originates from defects created during the production of higher index plane fracture surfaces.
展开▼
