Auger and electron energy loss spectroscopies of small palladium particles supported on (111) oriented MgO films

Abstract

The most common tool used to characterize supported metal clusters is the transmission electron microscope. The main advantage of TEM is the combination of high (lateral) resolution imaging with electron diffraction. However the TEM observations are usually made ex-situ i.e. UHV deposited clusters have to be exposed to the atmosphere during transfer to the TEM. This could be a severe limitation for very small reactive clusters. This paper demonstrates that electron spectroscopies can provide in-situ information on the cluster growth (AES), on the electronic structure (ELS) and on the local atomic order (SEELFS) of the clusters. These techniques were applied to Pd clusters of varying size (∼10-200 Å) vapor-deposited on thin (111) MgO support films under UHV conditions. An expansion of the lattice and a shift of the loss peaks towards higher energies are observed with decreasing particle size. © 1989 Springer-Verlag.