Metal cluster-rare gas van der Waals complexes: Physisorption on a microscopic scale
- Argonne National Lab., IL (United States)
Van der Waals complexes consisting of argon or krypton atoms bound to clusters of iron, cobalt, nickel, and niobium atoms have been generated by supersonic expansion from a liquid nitrogen-cooled laser vaporization source. Laser photoionization time-of-flight mass spectrometry reveals significant nonmonotonic variations in the efficiency of formation of these species as a function of metal cluster size. A correlation between these variations and the size-dependent reactivities of the bare metal clusters toward molecular hydrogen is observed. This correlation suggests that those metal cluster surface sites which readily support the binding of rare gas atoms are also highly reactive sites in direct cluster-hydrogen encounters. Alternatively, this correlation may imply that these cluster-hydrogen reactions occur by a two-step mechanism involving the production of a physisorbed M{sub n}{hor_ellipsis}H{sub 2} intermediate. Analysis of the post-threshold behavior in the photoionization efficiency spectra of niobium cluster-argon van der Waals species (Nb{sub n}Ar{sub m}) suggests that argon atoms bind with different efficiencies to each of the structural isomers of Nb{sub 7}, Nb{sub 9}, and Nb{sub 11}. 25 refs., 11 figs.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 468066
- Journal Information:
- Journal of Physical Chemistry, Vol. 96, Issue 16; Other Information: PBD: 6 Aug 1992
- Country of Publication:
- United States
- Language:
- English
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