Fjcs. Aires et al., MODEL CATALYSTS OBTAINED BY CLUSTER DEPOSITION OF PALLADIUM ONTO HOPG- TEM AND STM CHARACTERIZATION, Microscopy microanalysis microstructures, 4(5), 1993, pp. 441-452
Supported particles (model catalysts used in hydrogenation reactions)
are obtained by cluster beam deposition onto HOPG and characterised by
transmission electron microscopy (TEM) and scanning tunneling microsc
opy (STM). TEM shows the formation of groups of particles on the surfa
ce and the decoration of the steps of graphite. The groups of particle
s on the surface are well separated from each other. STM large scale o
bservations agree with these observations. A detailed experimental stu
dy of the (square-root 3 x square-root 3)R30-degrees periodic charge d
ensity modulations of the graphite observed around the particles is pr
esented and these modulations are interpreted in terms of a perturbati
on introduced by the particle to the degenerate wave functions of grap
hite, lifting up the degeneracy and yielding the (square-root 3 x squa
re-root 3)R30-degrees superstructure.