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Oxygen abstraction from dioxygen on the Al(111) surface
A J Komrowski1, J Z Sexton, A C Kummel
1U.C.S.D. Department of Chemistry and Biochemistry, La Jolla, California 92093, USA.
Physical Review Letters
|December 12, 2001
Summary
Abstractive chemisorption of oxygen on aluminum surfaces is an activated process. This study experimentally verified abstractive chemisorption, challenging existing adiabatic models.
Area of Science:
- Surface Science
- Materials Chemistry
- Physical Chemistry
Background:
- The initial oxidation of aluminum surfaces is crucial for understanding material degradation and passivation.
- Current models often assume non-activated adsorption pathways for oxygen on Al(111).
Purpose of the Study:
- To experimentally investigate the mechanism of initial oxygen interaction with Al(111) surfaces.
- To determine if abstractive chemisorption is an activated process.
Main Methods:
- Utilizing variable incident energy of molecular oxygen (O2) on Al(111).
- Employing Scanning Tunneling Microscopy (STM) to observe surface reaction products.
- Detecting ejected oxygen atoms in the gas phase using Resonant Enhanced Multiphoton Ionization (REMPI).
Main Results:
- Observed a transition from single O-adatom to O-adatom pair products with increasing O2 incident energy.
- Experimentally confirmed abstractive chemisorption as an activated process.
- Dissociative chemisorption was also found to be activated.
Conclusions:
- Abstractive and dissociative chemisorption of O2 on Al(111) are activated processes.
- These findings contradict predictions from current adiabatic absorption models.
- The incident energy of O2 plays a critical role in determining the chemisorption pathway.