A broad range of state-of-the-art methods to determine properties of clusters are presented. The experimental setup and underlying physical concepts of these experiments are described. Furthermore, existing theoretical models to explain the experimental observations are introduced and the possibility to deduce structural information from measurements of dielectric properties is discussed. Additional case studies are presented in the book to emphasize the possibilities but also drawbacks of the methods.

Optical Properties of Metal Clusters deals with the electronic structure of metal clusters determined optically. Clusters - as state intermediate between molecules and the extended solid - are important in many areas, e.g. in air pollution, interstellar matter, clay minerals, photography, heterogeneous catalysis, quantum dots, and virus crystals. This book extends the approaches of optical molecular and solid-state methods to clusters, revealing how their optical properties evolve as a function of size. Cluster matter, i.e. extended systems of many clusters - the most frequently occuring form - is also treated. The combination of reviews of experimental techniques, lists of results and detailed descriptions of selected experiments will appeal to experts, newcomers and graduate students in this expanding field.

The matrix isolation (MI) method has now been used for nearly thirty years. During this period it has been actively developed and the range of problems tackled greatly extended. Originally it was used for studies of transient species involv ing vibrational, electronic and ESR spectroscopy. Nowadays the study of transient species forms a comparatively small part of HI work since it has been amply demonstrated that very fruitful information can be obtained of the structure and interactions of stable molecules and their aggregates. In addition to the s~ectroscopic methods mentioned above the MI technique is nowadays a standard method in research based on vibrational relaxation, luminescence, Mossbauer, magnetic circular dichroism, pulsed NMR and photoelectron spectroscopy. The matrix isolation technique affords considerable advantages over more conventional methods in most applications of spectroscopy. Areas where the technique has been widely applied, or shows great potential, include: metal atom chemistry, and its relation to surface chemistry, high temperature inorganic species, transition metal complexes, interstellar species, free radicals and unstable molecules, conformational studies, molecular com plexes, and intermolecular forces.

This volume contains papers which have been presented at the International Sym posium on Metal Clusters in Heidelberg from April 7-11, 1986. Clusters, and in particular metal clusters, have been the topic of fa~t growing scientific interest. Indeed, clusters constitute a field of interdisciplinary nature where both physical and chemical questions have to be addressed. Clusters are offundamental importance for the deeper understanding of the transition from atoms via molecules and larger aggregates of particles to the properties of solid materials. Moreover, metal clusters and their character istics are of vital significance for such applied topics as catalysis or photography. Experimentally, the field exhibited rapid progress in the last years. Different sources for clusters have been developed. Intense beams made possible the investigation of free neutral clusters and cluster ions as well. Even though a number of issues concerning metal clusters is still discussed controversially, the present volume tries to give an overview of current work in this field and to illustrate the large variety of experiments as well as the advances made possible by modern theoretical methods. Looking at the many interesting questions still to be addressed it is fair to propose a rapid further growth of this field.