"The Role of Clusters in the Design of Nano-Scale Systems"Prof. Puru Jena , Virginia Commonwealth University [Host: Joseph Poon/Louis Bloomfield]
ABSTRACT:
Atomic clusters consisting of a few to a few thousand atoms constitute a
new phase of matter intermediate between atoms and solids. Unlike
conventional nanostructured materials, the size and composition of these
clusters can be controlled one atom at a time. The properties of such
clusters brought about by their large surface-to-volume ratio, unique
geometry, low dimensionality and reduced coordination, exhibit novel
behavior quite unlike that in the bulk. For example, metallic elements can
be made to form ionic bonds while nonmagnetic and anti-ferromagnetic
materials can become ferromagnetic or ferrimagnetic. This talk will
introduce the principles for designing these clusters and discuss a concept
where clusters can be viewed as super-atoms - adding a third dimension to
the periodic table. Recent experimental evidence to support this idea will
be presented. Examples of cluster assembled materials will include
high-energetic materials involving Al(MnO4)3, alkali metal clusters
isolated in zeolites, transition metal clusters supported on organic and
metallic substrates, and manganese-oxide clusters passivated by acetate
ligands. Ultimately the properties of crystals composed of clusters as the
building blocks will be discussed. It is hoped that the synergy between
theory and experiment will lead to the synthesis of cluster assembled
materials with unique and tailored properties, thus creating new
opportunities in materials science at the dawn of the new millennium.
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Colloquium Friday, September 13, 2002 4:00 PM Physics Building, Room 204 Note special time. Note special room. |
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