Department of
Chemistry,
● Spectroscopy and Photochemistry of
Metal-Containing Clusters
● Cluster Models of Metal Ion Solvation and
Coordination
● Protonated Molecular Clusters and Proton
Transfer Dynamics
● Carbocations and Laboratory Studies of
Interstellar Molecules
● Synthesis of Nanocluster Materials
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Dr. Michael A. Duncan Department of Chemistry
Office: 706-542-1998 Journal of Physical Chemistry Editorial Office
Fellow, American Physical Society, 2001 Fellow, American Association for the Advancement of
Science, 2004 Alexander von Humboldt Fellow, 2007- |
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August 2007
Front: Mike Duncan,
Biswajit Bandyopadhyay, Karen Molek
Middle: Joe
Velasquez, Zach Reed, Brian Ticknor, Gary Douberly
Back: Prosser Carnegie, Allen Ricks, Tim Cheng
Research Group:
CURRENT MEMBERS:
Allen Ricks, Graduate Student (aricks@gmail.com)
Brian Ticknor, Graduate Student (bticknor@uga.edu)
Joe Velasquez, Graduate Student (jviii@uga.edu)
Prosser Carnegie, Graduate Student (pcarnegi@chem.uga.edu)
Zach Reed, Graduate Student (zachreed@uga.edu)
Tim Cheng, Graduate Student (timccheng@gmail.com)
Biswajit Bandyopadhyay, Graduate Student (biswajit@uga.edu)
Gary Douberly, Postdoc (douberly@email.unc.edu)
Our research
program works on the synthesis and characterization of novel atomic and
molecular clusters containing metals. These clusters may consist of only
a few atoms of pure metal, mixtures of metals, or metal compounds (carbides,
oxides, etc.), or they may be a metal center with one or more molecules
attached to it. The overall goal is the elucidation of the chemical
bonding between metals and at the metal-molecular interface. The work is
fundamental, but practical implications are easily found in heterogeneous
catalysis, physisorption on metal surfaces, production of microelectronic
materials, metal-ligand bonding, metal ion solvation, atmospheric meteor
ablation chemistry, astrophysics and interstellar dust, and interactions in
metal and semiconductor plasmas. In all projects, the metal systems are
produced in a gas phase/molecular beam environment using pulsed laser
vaporization of metal targets. The resulting clusters and/or metal
complexes are analyzed and size selected using time-of-flight mass spectrometers.
A significant component of the research focuses on the design and optimization
of time-of-flight mass spectrometers. High resolution spectroscopy
measurements are conducted using a variety of tunable visible, ultraviolet and
infrared lasers, using the techniques of laser induced fluorescence, laser
multiphoton ionization, laser multiphoton photodissociation and laser
photoelectron spectroscopy. These studies investigate the electronic
orbital energies, bonding configurations, ionization potentials, vibrational
frequencies, bond energies, bond distances, geometric structures and
photochemical pathways in the clusters. We study neutral clusters as well
as positive and negative ions.
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Research Areas: |
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Metal Ion
Complexes |
Metal-Carbide
and Oxide Cages and Nanocrystals |
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Protonated
Water Clusters |
Novel
Organometallic Clusters |
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Other
Protonated Molecular Clusters |
Laser
Desorption Mass Spectrometry of Thin Films |
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Carbocations |
Synthesis
of Ligand-Coated Nanoparticle Materials |
This is a photograph of the
inside of one of our "source" chambers where clusters are
produced. The sample in this example is a silver rod hanging down from
above that is mounted in a special holder that we built. The laser comes
through the window on the opposite side and hits this rod as it is
rotating. A spray of helium or argon gas flows over the metal rod surface
where the laser hits the rod. The metal-containing cluster molecules
spray out of this (toward the right in this figure) and the center part of this
spray goes through the hole in the "skimmer" (the silver cone-shaped
device mounted on the right wall). This gas then goes into another vacuum
chamber connected to this one where the mass spectrometer is located.
Here is
a photograph of one of our beam machines with the reflectron time-of-flight
mass spectrometer
(our lab has three of these instruments):
Clusters are produced in the
source chamber on the right (see expanded photo above) and then they flow
through the skimmer into the second chamber at left where the mass spectrometer
is loctated. Two pipes come out of this chamber to make the flight tube
for the time-of-flight mass spectrometer. The ions are reflected down the
second pipe in the turning region, which is the can closest and to the
left. This is where the laser excites the ions.