Collect. Czech. Chem. Commun. 1988, 53, 1613-1619

XPS determination of dimensions of metal clusters on supports

Tomáš Juška

Institute of Inorganic Chemistry, Czechoslovak Academy of Sciences, 160 00 Prague 6


The applicability of the XPS technique to the indirect determination of the size of metal clusters on supports was tested on two types of the Ag/Al2O3 system. For clusters formed from vapour deposited layers, relations were derived enabling the size to be determined from photoemission line intensities of the metal measured after deposition at liquid nitrogen temperature and after heating to 25 °C or 400 °C. For metal clusters on supported Ag/α-Al2O3 catalysts, their size was estimated by using two models, viz. the Kerkhof-Moulijn model and the Kuipers-van Leuven-Visser model. Spherical and hemispherical shapes of the clusters were assumed for the two Ag/Al2O3 systems, and the results were confronted with electron microscopy photographs. The Kuipers-van Leuven-Visser model applied to the supported catalyst was found to fit the reality better than the Kerkhof-Moulijn model.