Physical Properties and Characterisation of Small Gold Particles

Physical Properties and Characterisation of Small Gold Particles 

Small particles are energy-rich, because the work that has to be done in subdividing a large piece of metal is used to break chemical bonds, and this energy ends up in the free valences or dangling bonds thereby created. As size is decreased, the proportion of atoms at or close to the surface that are incompletely bound to neighbours therefore increases the lower the mean 

There are many ways in which small metal particles can be created and examined (Section 3.2). When the gold particles are supported, the first step is to determine their mean size and size distribution for this there is no real substitute for transmission electron microscopy (TEM). The various energetic and electronic properties then need to be examined, and the bases of the available experimental techniques will be briefly rehearsed in Section 3.3. Of particular interest is the point at which the change from metallic to nonmetallic behaviour occurs as size is decreased, because this corresponds very roughly to the point at which catalytic activity (at least for oxidation of carbon monoxide) starts to rise dramatically. Relevant experimental results and theoretical speculations are reviewed in Section 3.4. 

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