Imaging and spectroscopy of α-Al 2O 3, diamond, Ni and Fe bulk crystal surfaces

Abstract

Reflection electron microscopy (REM) and reflection electron energy-loss spectroscopy (REELS) have been used to study the structures of several bulk crystal surfaces of practical importance. Different radiation damage responses to the electron beam were found on both the α-Al 2O 3 (0–1) and (0–2) surfaces for regions with different atomic terminations. The damage causes desorption of oxygen ions from surface domains initially terminated with oxygen. Surface microanalysis by REELS is complicated by the channeling of electrons along the different atomic planes parallel to the surface under resonance conditions, but the effect was used to measure the density of absorbed oxygen atoms. The variation in contrast of alumina (0–2) with changes of diffraction conditions cannot be interpreted based on the traditional criterion for surface resonance; a new criterion is introduced for identifying true resonance. Synthetic diamond grains in the as-received condition were imaged with REM and surface steps were observed. Nickel (110) surfaces were found to have a terraced structure with offset step modulations. REELS easily detected the NiM and NiL edges but failed to detect any light elements expected to be adsorbed at the surfaces. It was difficult to image iron surfaces due to strong magnetic deflection, but reasonable FeL edge REELS spectra were obtained.