High-Resolution Electron Energy-Loss Studies of Metal Oxides

Abstract

Studies of ordered MgO and NiO have been carried out by synthesizing ultra-thin films under ultra-high vacuum (UHV) conditions via evaporating Mg and Ni onto Mo(100) in the presence of oxygen. Low-energy electron diffraction (LEED) studies indicate that the films grow epitaxially with their (100) faces oriented parallel to Mo(100). The MgO and NiO films, prepared under optimum synthesis conditions, have essentially one-to-one stoichiometry, are nearly free from point-like surface defects, and have properties essentially identical to their bulk, single-crystal counterpart. Molecular adsorption onto the films has been studied using High-Resolution Electron Energy-Loss Spectroscopy (HREELS) and temperature programmed desorption (TPD). In order to circumvent the difficulty associated with intense multiple surface optical phonon (Fuchs-Kliewer modes) losses, a new approach to acquisition of HREELS data has been demonstrated. This new approach enables the direct observation of weak loss features due to excitation of the adsorbates without serious interference from multiple phonon losses.KeywordsTemperature Program DesorptionDesorption FeatureLEED PatternTemperature Program Desorption SpectrumOptimum Synthesis ConditionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.