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Condensed Matter Theory

Cluster Catalysis

(a) Aln + CH4

Bulk Aluminum and large Aluminum clusters do not interact with CH4.
Small Aluminum neutral or charged clusters (of 2, 3, 4, 5 atoms) can interact with CH4 at temperatures of 400 - 800 o C, forming methyl-aluminum-hydrides.
The larger the cluster is, the hardest the reaction, depending on the charge and the total spin.

''Investigation of the reaction between Aluminum clusters and Methane'', E. Alexandrou, H.M. Polatoglou and N.C. Bacalis, International Conference on Computational Methods in Science and Engineering (2008), Hersonissos, Crete, Greece, 25 - 30 /9/ 2008 (oral presentation)

Collaborators:
Prof. Dr. Axel Gross, Ulm University, Germany.
Dr. Hariton Polatoglou, Assoc. Prof. of Physics, Aristotle University of Thessaloniki, Greece.
Dr. Nicolaos Papanicolaou, Assoc. Prof. of Physics, University of Ioaninna, Greece.

(b) Al4 + O2

Aluminum presents a small hindrance in the adsorption of O2 on the surface.
Why? - There is no potential barrier.

Anomalous surface can be simulated by small tetrahedral Al4 clusters.

O2 reacts slightly with the cluster when it approaches the pyramid apex, trapped locally near the apex (in a potential energy local minimum).

Drastic electronic rearrangement occurs when it approaches just above the apex.

But O2 has enough energy to escape the little trap while it approaches the surface.
Then it is adsorbed finding the deeper energy minimum, below the apex.

NC. Bacalis, A. Metropoulos and A. Gross, unbublished.

Collaborators:
Prof. Dr. Axel Gross, Ulm University, Germany.
Dr. Aristophanes Metropoulos.


 

 

 

 

 

 

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