PHOTOELECTRON DIFFRACTION IMAGING OF MICROCRYSTALLITES ON THE SURFACEOF A NI POLYCRYSTAL

The applicability of the forward scattering of photoelectrons in elect ron microscopy is demonstrated for the characterization and investigat ion of the polycrystalline substrates. The well-resolved images of ind ividual microcrystallites on the surface of Ni polycrystal have been o btained by using the Ni 2p(3/2) photoelectrons (E-kin = 635 eV) collec ted at a widely variable direction of emission. By using the forward s cattering approach, not only crystallites resolved by an optical micro scope but also the microcrystallites, which were not distinguished by the optical method, have been easily identified through the photoelect ron diffraction contrast. This contrast amounted to almost 50% of the whole intensity scale and could be observed directly during the acquis ition of the images. Crystallographic information on the orientation o f the microcrystallites constituting the polycrystal was obtained: som e crystallites with the low index surfaces were identified, some micro crystallites with the same orientation were recognized, and the symmet ry of the surfaces of the individual crystallites was partly controlle d. An approximate identification of the crystallographic orientation o f several individual microcrystallites in the investigated Ni polycrys tal has been achieved.