PNNL

Abstract

Photoelectron spectroscopy is used to investigate aluminum dideuteride cluster anions, AlnD2 - _n=3,6–15_, produced by laser vaporization of a pure Al target with a D2-seeded helium carrier gas. Comparison between the well-resolved photoelectron spectra of AlnD2 - and Aln - reveals the nature of interactions between D2 and Aln -. Depending on the size of the Aln - clusters and their electronic structure, three types of AlnD2 - species are observed, dideuteride _dissociative chemisorption_, molecular chemisorption, and physisorption. Striking spectral similarities are observed between photoelectron spectra of AlnD2 - and Aln - for n=9, 11, 13, and 15, suggesting that D2 is physisorbed on these closed-shell Aln - clusters. For AlnD2 - with n=3, 6, 7, and 10, completely different spectra are observed in comparison with the corresponding Aln - clusters, suggesting that the AlnD2 - species may be characterized as dideuterides. For AlnD2 - with n=8, 12, and 14, in which the Aln - clusters are open shell, the D2 is characterized as chemisorption on the basis of spectral shifts and similarities relative to those of the corresponding Aln - clusters. © 2006 American Institute of Physics.