MATERIALS SCIENCE COLLOQUIUM

Refreshments will be served at 10:45 a.m.

ABSTRACT: Heterogeneous catalysis is a major synthetic approach to the generation and production of new materials and important industrial chemicals. Moreover, small clusters and nanoparticles are often responsible for inducing new chemical reactions, both wanted and unwanted. Our studies are focused on the mechanisms for both types of reactions (catalysis and nanoparticle), because mechanistic understanding in these instances (currently unavailable) can lead to improved catalytic reactions and better control over nanoparticle and cluster chemistry, in general. In this presentation we will discuss three catalytic reactions dealing with the following chemistry:

1. as the catalyst;
2. with Com as the catalyst; and
3. 2 CO + O2 2 CO2 with Aum as the catalyst.

In each instance the neutral catalytic clusters are generated through laser ablation/supersonic expansion/expansion cooling and they are passed into a reaction cell with the appropriate chemicals. Reactants and products are analyzed through single photon ionization of the neutral species with 6.4 eV, 10.5 eV, and/or 26.5 eV laser light and detection of the ensuing ions through time of flight mass spectrometry. These experiments serve to identify the active cluster species and their products. With this information, calculations are undertaken to generate thermodynamically allowed mechanistic pathways for each cluster reaction. From this information, a catalytic cycle can be generated that can be tested against known condensed phase appropriate reactions and improved catalytic conditions can be proposed.
In addition, new clusters of the form MmCnHx, with M= Al, Mg, Be, that can store up to 20-30 wt % of hydrogen, will be discussed. These systems may be useful for applications as fuel sources for mobile power generation.