R. L. Cohen

Hydrogen storage materials: properties and possibilities

The physics, chemistry, and possible applications of the storage of hydrogen in intermetallic reservoirs are discussed. Storage in the form of intermetallic hydrides can be safe and, where hydrogen has some special value as a fuel, economical. New pumps and refrigerators based on the heat of sorption of the hydrogen into the intermetallic are approaching commercial viability.

Dependence of iridium Mössbauer isomer shifts on oxidation state: an inversion for low valent carbonyl complexes

Abstract The 193 Ir Mossbauer isomer shifts of a set of closely related iridium carbonyl chloride complexes with oxidation states +1, +1.1, +1.4, and +2 have been found to decrease with increasing oxidation state. This is the inverse of the normal trend due to decreased shielding of the s electrons from the nuclear charge by removal of d electrons, and is attributed to the combined effect of strong π-backbonding and 6s character in the nominally 5d electrons removed in changing the oxidation state. An inverted isomer shift-oxidation state dependence is predicted for d m ( m > 7) metal complexes with strong π-acceptor ligands.

Mössbauer spectroscopy: recent developments.

In this review I have emphasized two basic points. First, M�ssbauer spectroscopy has been widely used as a tool for basic research in solid-state physics, chemical structure, and magnetism. Second, the technique has been applied to many analytical and materials science problems where the nature of the sample prevents the use of more traditional approaches. M�ssbauer spectroscopy research on frozen solutions, colloids, interface chemistry, and crystallographic transformations can be expected to increase rapidly in the next few years.