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Metastable structures and recombination pathways for atomic hydrogen on the graphite (0001) surface.
L Hornekaer1, Z Sljivancanin, W Xu
1Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, University of Aarhus, Ny Munkegade bygning 1520, 8000 Aarhus C, Denmark. liv@phys.au.dk
Physical Review Letters
|May 23, 2006
Summary
Two hydrogen dimer states on graphite surfaces were identified using scanning tunneling microscopy. One state
Area of Science:
- Surface science
- Materials science
- Physical chemistry
Background:
- Hydrogen adsorption on surfaces is crucial for catalysis and materials science.
- Understanding hydrogen dimer formation and stability is key to controlling surface reactions.
Purpose of the Study:
- To investigate the distinct states of hydrogen dimers on graphite basal planes.
- To elucidate the atomic structure and stability of these dimer states.
- To explain the observed double peak in temperature-programmed desorption spectra.
Main Methods:
- Scanning tunneling microscopy (STM) for real-space imaging of hydrogen dimers.
- Density functional theory (DFT) calculations for atomic structure and reaction pathway determination.
Main Results:
- Identified two distinct hydrogen dimer states on graphite basal planes.
- Determined the atomic structures and recombination/desorption pathways for both states.
- Found that direct recombination is only possible from one dimer state, leading to increased stability.
Conclusions:
- The differential stability of the two hydrogen dimer states explains the double peak observed in temperature-programmed desorption spectra.
- The findings provide fundamental insights into hydrogen-surface interactions on graphite.