Photoelectron spectroscopy of AlnD-2 (n=3-15):: Observation of chemisorption and physisorption of dideuterium on aluminum cluster anions -: art. no. 054308

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 D-2-seeded helium carrier gas. Comparison between the well-resolved photoelectron spectra of AlnD2- and Al-n(-) reveals the nature of interactions between D-2 and Al-n(-). Depending on the size of the Al-n(-) 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 Al-n(-) for n=9, 11, 13, and 15, suggesting that D-2 is physisorbed on these closed-shell Al-n(-) clusters. For AlnD2- with n=3, 6, 7, and 10, completely different spectra are observed in comparison with the corresponding Al-n(-) clusters, suggesting that the AlnD2- species may be characterized as dideuterides. For AlnD2- with n=8, 12, and 14, in which the Al-n(-) clusters are open shell, the D-2 is characterized as chemisorption on the basis of spectral shifts and similarities relative to those of the corresponding Al-n(-) clusters. (c) 2006 American Institute of Physics.