Penn State Castleman Group

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Updated January 7, 2014


Cluster Deposition and Reactivity
Jordan Smith

We study gas phase reaction kinetics of metal clusters (molecules with less than 100 atoms). The properties of clusters are highly dependent on their size and the addition or removal of just one atom can change a cluster’s properties completely. Understanding cluster reactivity can help us develop tunable materials with possible catalytic or energetic qualities. Aluminum is the primary metal that we study because of its potential as a high-energy-density material. Aluminum nanoparticles are currently used as fuel additives and in explosives; their effectiveness is primarily limited by a layer of aluminum oxide that forms around the nanoparticle. Previous studies in our group have found aluminum cluster ions that are resistant to oxidation and are a step towards making aluminum a more efficient energy source. Our studies also investigate the reactivity properties of noble metal cluster such as Au, Ag, and Cu.

In addition to gas-phase studies we also study methods of depositing clusters onto a surface. When a cluster impacts a surface its geometric structure is often lost and so are the unique properties of the cluster. We use information gained from gas-phase research to provide pathways that allow us to deposit clusters onto a surface while maintaining the integrity and specific properties of the clusters.

We have recently modified our instrument to include a cavity ring-down chamber to provide spectroscopic analysis of cluster—cluster interactions. We will be able to observe how clusters interact with each other and how specific cluster ions react with complementary reagent ions. Hopefully this will lead to a better understanding of clusters and ways to construct stable cluster compounds.

MIFT Diagram

A. Ion Source.
B. Fast-Flow Reactor
C. Collisional Focusing Conical Octopole
D. Differential Pumping
E. Quadrupole Mass Spectrometer
F. Ion Current Detector