par Kruse, Norbert
Référence Ultramicroscopy, 89, page (51-61)
Publication Publié, 2001-01-03
Article révisé par les pairs
Résumé : Recent progress in imaging surface chemical reactions and adsorbate-induced reconstruction by means of field ion microscopy is reviewed . Achievements and prospects of a local chemical analysis during imaging afe also presented and discussed. Major shape transformation is reported to occur during the field-free interaction of oxygen with Rh crystal tips. Rather than hemispherical when clean they appear polyhedral after reaction at temperatures between 500 and 550 K. Kinetic non-linearities are found in both the NO and NO2 reaction with hydrogen on the surface of a pyramidal Pt crystal tip. Oscillatory reaction behavior is observed for both reactions. In the NO2-H2 case explosive ignition in {O I 2} planes is followed by one-dimensional chemical wave propagation along the <100) zone lines. Atom-probe time-of flight mass spectrometry demonstrates that water (field ionized as H20+ and H30+) is the product of the catalytic reaction. During the NO/H2 reaction , dynamic formation and motion of small islands arc observed. These islands appear on the (001) pole and are interpreted as being due to adsorbed hydroxyl species. Island sizes are confined to the equivalent of 10-30 Pt atoms.