Aydin, M: Photofragmentation Spectroscopy

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, optical, and magnetic properties vary with cluster size, eventually reaching those of the bulk metal. Even for small transition metal (ionic) clusters, their electronic structures are complexes and remain questions. For theory, too, the future holds its challenges. Even cluster as small as diatomics may prove difficult species to get right answers for because of the partially occupied d orbitals. Therefore, it is difficult to calculate the exchange-correlation energy contribution to the system in an accurate manner.