Abstract: An ultrasharp diamond edge or point, which may be a monocrystalline diamond cut and ground to provide an ultrasharp edge or point or a polycrystalline diamond molded from ultrafine diamond or graphite powder to form an ultrasharp edge or point is irradiated with an electron microbeam and preferably simultaneously is subjected to a controlled jet of highly purified gas in an enclosure at low temperature and low pressure to smooth out any minute irregularities and to obtain an atomic smoothness, glazing and annealing. By selectively masking the surface of the diamond edge or point or facet planes, the effect of the irradiation or jet can be confined to well defined areas.

Abstract: Ultrasharp diamond edges and points which are usable as high intensity point sources for the emission of electrons, ions, X-rays, coherent and incoherent light and high frequency electromagnetic radiation are produced by preparing and classifying ultrafine diamond powder having a particle size of 10 to 100 angstroms, placing the powder in a diamond mold defining the ultrasharp edge or point to be produced and applying a pressure of the order of 80 to 90 kb while heating the powder to a temperature of the order of 2440.degree. K. in an ultrahigh vacuum or inert atmosphere after degasing to avoid oxidation of the diamond powder.