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Encyclopedia of Physical Science and Technology EN009M-428 July 18, 2001 1:6

Metal Particles and

Cluster Compounds

Allan W. Olsen
Kenneth J. Klabunde

Kansas State University

I. Metallic Elements
II. Metal Particles
III. Metal Cluster Compounds

GLOSSARY Nanocrystal A crystalline piece of solid matter less than
100 nm in diameter.
Arachno Polyhedron two vertices short of close config- Nanoparticle A crystal or aggregate of crystals of solid
uration (weblike). matter less than 100 nm in diameter.
Closo Deltahedron (all triangular faces, closed configu- Nido Polyhedron one vertex short of closo configuration
ration). (nest like).
Cluster Group of atoms bound together. Nuclearity Number of metal atoms bound together.
Colloid Particle small enough to remain suspended in so- Plasmon Collective oscillation of electrons in a solid, of-
lution or a gas. ten of characteristic frequency.
Coordination sphere Immediate vicinity around a metal Sintering Growth of metal particles by movement and
atom. agglomeration of smaller particles.
Coordinative unsaturation Open binding site(s) on a Sol Similar to a colloidal particle; a particle that remains
metal atom due to loss of a ligand. suspended in a solution.
Fermilevel Energydifferencebetweenelectronfilledand Work function Energy to pull an electron off of a bulk
unfilled levels in a semiconductor (the chemical poten- metal.
tial at 0 K).
Isolobal Two molecular fragments with similar orbital
energies and symmetries. VERY SMALL pieces of metal, each made up of only
Knudsen cell High-temperature furnace with one small a few atoms, constitute an unusual form of matter.
pin hole exit for high-temperature vapors to escape. These metal particles/clusters by themselves exhibit high
Ligand Molecule bound to a metal atom or cluster. chemical and catalytic reactivity, as well as unusual mag-
Ligation Act of bonding a metal with a ligand. netic and spectroscopic properties. In addition, these metal

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