AVS 47th International Symposium
    Surface Science Monday Sessions
       Session SS1-MoM

Paper SS1-MoM1
STM Study of H - Al (111): From Alane-Formation Reactions to Absorption-Induced Roughening

Monday, October 2, 2000, 8:20 am, Room 208

Session: Atomic-Scale Studies of Model Catalysts
Presenter: M. Noh, University of Maryland
Authors: M. Noh, University of Maryland
J.E. Reutt-Robey, University of Maryland
Correspondent: Click to Email
We investigated the reaction of atomic hydrogen with Al (111) with STM under UHV conditions. We show that hydrogen reacts strongly with the substrate to form aluminum hydride oligomers (alanes) which are stable up to ~350K. At lower reaction temperatures (T< ~230K), the distribution of surface alanes is highly nonuniform, with one dimensional strings of alanes extending for thousands of Å. These strings act as mass barriers that direct the distribution of later-form alanes. The alane strings run roughly parallel to crystallographic steps and exhibit a terrace-width-dependent nucleation. We discuss the physical origin of these intriguing reaction patterns. These surface reactions are accompanied by hydrogen absorption. Subsurface hydrogen is sensed indirectly by regions of increased surface roughness that can eventually leads to delamination. * Supported under NSF contract DMR-9632521 and CHE-9800470.