A technique for efficiently generating bimetallic clusters

Abstract

Reactivities of bimetallic clusters can be controlled by varying their composition, making them potentially valuable as catalysts and for use in elucidating the reactivities of such subnanoscale surfaces. A 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 Nb/Al clusters are formed in two plasmas induced by the second harmonic (532 nm photons) of a single Nd:YAG laser and then detected by a quadrupole mass spectrometer. The beam from the laser is split and then focused onto 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 V/Al clusters.

Characterization of neutral boron-silicon clusters using infrared spectroscopy: The case of Si6B

“…To produce mixed clusters, various approaches have been demonstrated, such as single targets of alloys [34], binary compounds [35][36][37], pressed mixed powders [38,39], and dual-target (dual-laser) sources [40][41][42][43][44]. The dual-target dual-laser source designs allow for controlling the mixing ratios by changing the laser fluences, laser timing, and the rotation and/or translation speeds of the targets.…”

Cluster reactivity experiments: Employing mass spectrometry to investigate the molecular level details of catalytic oxidation reactions

“…A variety of cluster formation methods, primarily including laser vaporization (LaVa) (10)(11)(12), pulsed-arc discharge (PACIS) (13)(14)(15), electrospray ionization (ESI) (16), gas aggregation (17)(18), and inert gas sputtering (CORDIS) (18) have enabled the creation of both positively and negatively charged as well as neutral gas-phase clusters across a large size range and with diverse elemental composition. The thermodynamic properties of clusters, including bond-dissociation energies (19)(20)(21), endothermic-reaction barriers (22), heat capacities (23), and the enthalpy, entropy, and free-energy changes associated with clustering reactions (24,25), including those composed of hydrogen-bonded and van der Waals systems, have been widely studied, employing both GIB-MS and flow-tube experiments.…”

Stability patterns of multiphoton ionized YAun clusters

“…Binary metal clusters are produced by a laser vaporization source. The laser vaporization technique for bimetallic cluster production, developed for metals with high boiling points, is mainly applied using dual rod sources and one or two lasers for vaporization [3,11]. Our concept of binary cluster production is based on the application of two vaporization lasers, however, the targets of the cluster source are disks.…”