par Visart de Bocarmé, Thierry 
;Bar, Thomas ;Kruse, Norbert
Référence European Conference on Surface Science (ECOSS) (18: 1998-09-19->24: Vienne, Autriche)
Publication Non publié, 1998-09-24
;Bar, Thomas ;Kruse, Norbert Référence European Conference on Surface Science (ECOSS) (18: 1998-09-19->24: Vienne, Autriche)
Publication Non publié, 1998-09-24
Communication à un colloque
| Résumé : | Oxygen-covered Rh crystal were probed for their reactivity with hydrogen to form water using video-FIM (Field Ion Microscope) at temperatures of 400 to 500 K and pressures up to 10-2 Pa. Following on previous work, a polyhedral Rh crystal was prepared by reaction with oxygen. Subsequent imaging in hydrogen at 400 K was found to provoke water formation in an explosive manner. The video sequence allowed ud to make visible the ignition of the reaction in the central (001) pole and the propagation of the respective chemical wave towards the outskirts of the tip sample. On the other hand, experiments with stoichiometric amounts of hydrogen and oxygen demonstrated chemical waves to move from the shank towards the apex part of the tip. In this case planes like (012) and (011) lying along (001) zones act as barriers to the water formation, i.e. the four quadrants of the (001) oriented apex react independently from each other. |
