E-viri
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Lubcke, M; Sonntag, B; Niemann, W; Rabe, P
Physical review. B, Condensed matter, 10/1986, Letnik: 34, Številka: 8-IJournal Article
The L sub III absorption thresholds of Pr, Nd, and Sm clusters isolated in solid Ar are marked by prominent white lines. The lines ascribed to divalent and trivalent rare-earth metals are well separated in energy. From the relative intensities of these lines an average valence of the rare-earth atoms in the cluster has been determined. For dimers and trimers the average valence is close to two, the value for free atoms. For clusters consisting of > 20 atoms the average valence approaches three, the value for bulk metals. In between the valence changes abruptly, indicating the existence of a critical cluster size of approximately five atoms for Pr and Nd and of 13 atoms for Sm. 46 ref.--AA
