EXTENDED X-RAY-ABSORPTION FINE-STRUCTURE OF SMALL CU AND NI CLUSTERS - BINDING-ENERGY AND BOND-LENGTH CHANGES WITH CLUSTER SIZE

Extended x-ray-absorption fine-structure measurements have been made on metal clusters of Cu and Ni which were formed by vapor deposition on amorphous carbon substrates. Small clusters of both elements show a substantial contraction of the nearest-neighbor metal-metal distance and an increase in binding energy for the onset of the K absorption edge. The results are explained by the increasing surface-to-volume ratio as the cluster size decreases resulting in a more free-atom like configuration of the metal atoms. © 1979 The American Physical Society.