A metal cluster is a group of metal atoms consisting
of two to several thousand metal atoms in gas,
liquid, solid, and plasma phase. Chemical physicists
studying the spectra of transition metal clusters
produced in supersonic nozzle beams and detected by
either resonant two-photon ionization or
photofragmentation allude in their discussions to the
metal-metal multiple bonding. In the field of cluster
chemistry and physics the aim is to understand how a
chemical process depends on cluster size, how the
chemistry of a metal changes with its state of
aggregation, and how structural, electronic,...