Metal clusters, experimental

W. A. De Heer The physics of simple metal clusters Experimental aspects and simple models, Rev. Mod. Phys. 65, 611 (1993)... 

The reactivity of size-selected transition-metal cluster ions has been studied witli various types of mass spectrometric teclmiques [1 ]. Fourier-transfonn ion cyclotron resonance (FT-ICR) is a particularly powerful teclmique in which a cluster ion can be stored and cooled before experimentation. Thus, multiple reaction steps can be followed in FT-ICR, in addition to its high sensitivity and mass resolution. Many chemical reaction studies of transition-metal clusters witli simple reactants and hydrocarbons have been carried out using FT-ICR [49, 58]. 

Gingerich, K.A. (1980) Experimental and Predicted Stability of Diatomic Metals and Metallic Clusters. Faraday Symposia of the Chemical Society, 14, 109-125. 

Several characteristics of the metal beam have been studied in detail. It is well known that metal clusters and metal oxides are formed as a result of the ablation process. However, these potentially interfering species have been studied in detail130 and it has been concluded that they do not introduce any doubt as to the validity of the experimental results. Much more important than cluster or oxide formation are the atomic electronic state populations of the metal beams. For each metal reactant, these have been characterized using laser-induced fluorescence (LIF) excitation spectroscopy. For Y, only the two spin-orbit states of the ground electronic state (a Dz/2 and a D-3,/2) were observed.123... 

Geometric structure of the bare metal clusters and the complexes formed by reaction are unknown and present a significant experimental challenge. Chemical studies are starting to imply something about the structure of the products and will be invaluable until more direct chemical physics probes are available. 

In this paper, the photofragmentation of transition metal cluster complexes is discussed. The experimental information presented concerning the gas phase photodissociation of transition metal cluster complexes comes from laser photolysis followed by detection of fragments by ionization (5.). Ion counting techniques are used for detection because they are extremely sensitive and therefore suitable for the study of molecules with very low vapor pressures (6.26.27). In addition, ionization techniques allow the use of mass spectrometry for unambiguous identification of signal carriers. 

Although STM is not a particularly fast observation technique, the growth of a metal cluster can still be monitored during its initial stages, provided the growth rate is slowed down by appropriate experimental parameters, such as overpotential and electrolyte composition. In addition, the interference of the STM tip with electro-... 

The observation of O-protonation with the attendant formal reduction of the carbonyl carbon suggested to us that further protonation steps might lead to methane or methanol formation. In this process the necessary electrons for the reduction would be provided by the metal cluster, as indicated schematically in equation 21. After considerable experimentation with reactants... 

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