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Bimetallic Clusters: Insights into Reactions of Subnanoscale Surfaces.
PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF CHEMISTRY
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Reactivities of bimetallic clusters can be controlled by varying their composition, making them potentially useful as catalysts and valuable for use in elucidating the reactivities of such subnanoscale surfaces. A new dual rod laser vaporization source coupled to a fast flow reactor is developed for the study of bimetallic clusters and their reactions. In order to establish the versatility of the technique, the results of studies are presented in which NbAl clusters are formed in two plasmas induced by the second harmonic 532 nm photons of a single NdYAG laser and then detected by a quadrupole mass spectrometer. The beam from the laser is split and then focused on to each rod, allowing the mixing ratio within the cluster to vary by altering the laser fluence on each rod. With a low fluence on the Nb rod and a high fluence on the Al rod, an Al rich cluster distribution is formed NbAlm m 2 - 20, and Alm m 5-31. By increasing the fluence on the Nb rod, and decreasing the fluence on the Al rod, a Nb rich cluster distribution is formed NbnAlm n 3-8 and m 1-3, NbnOAlm n 3-8 and m 1-5, and NbnO n 3-8. Additional characterization is also performed on VAl clusters.
APPROVED FOR PUBLIC RELEASE