Under the award, "Collaborative Research: Excited State Dynamics of Structurally Precise Metal Nanoclusters," the Ackerson lab at Colorado State University collaborated with the Knappenberger Lab of Pennsylvania State University and the Aikens Lab of Kansas State University.  In the overall collaborative award, the goal was to "make, measure and model" how energy can flow in the smallest possible discrete collections of atoms.  At less than one billionth of a meter in diameter, these discrete collections of atoms, or "nanoclusters" may be ultimately useful in  solar-to-electric energy conversion devices, optical sensors, and medical diagnostics and therapeutics, among others.  However, many of these proposed applications required understanding of how energy can flow in these nanoclusters.

The role of the Ackerson group in this award was to synthesize or make the nanoclusters that were being measured in cutting edge ways by the Knappenberger group and theoretically modeled by the Aikens group.  In this award, the Ackerson lab produced samples of nanoclusters that were subsequently measured in the Knappenberger lab.  Many of these samples came from known synthetic proceedures.  The role of the Ackerson lab was also to develop novel syntheses of gold clusters that contained additional non-gold atoms, in order that the effect of non-gold atoms on energy flow in these clusters could be measured and modeled.

We encountered some difficulty in synthesizing clusters with non-gold elements that were most desirable.  While less interesting elements such as Palladium and Cadmium could be integrated, more interesting elements such as Iron, Cobalt, Rhodium, and Iridium proved to be difficult.  Sometimes we observed evidence of synthetic success, but had difficulty isolating the desired products from other reaction products.   In the course of pursuing these more difficult elements, we made some fundamental findings about gold cluster synthesis, for instance, clarifying the role of atmospheric oxygen in these syntheses. Ultimately, we were able to incorporate Rhenium into Gold Clusters.  We still had difficulty with the purification of the Rhenium-Gold cluster compounds, but found that we could isolate mixtures containing just two compounds: a Rhenium-Gold compound and a pure-Gold compound.  The stability of the Rhenium-Gold compound depends on the presence of the pure-Gold compound.  We are working now to understand why that is. 

The results of these research findings were reported in several peer-reviewed papers, published in journals under the American Chemical Society family of journals and the Royal Society of Chemistry family of journals.  

In addition to the research findings, this grant was supported the training of several Chemistry PhD students, as well as several undergraduate students with majors in Chemistry, Chemical Engineering, and Biochemistry. 

As a further part of the training accomplished under this grant, all 3 PIs (Aikens, Knappenberger, Ackerson) put on a summer workshop targeted toward PhD students.  This workshop, which was conducted across all 3 campuses by viedoconference, covered the synthesis, spectroscopy, and modeling of the gold clusters studied in this grant.  The workshop was targeted towards students who may have expertise in one of the areas, but not in all 3. Prof Ackerson taught the module on synthesis (~10 lecture hours), and Prof Aikens and Prof Knappenberger taught modules on their areas of expertise.  Some students were able to receive course credit towards their PhDs on the basis of this summer workshop. 

Last Modified: 01/22/2020
Modified by: Christopher Ackerson