From left to right:

Tim Hogan (Associate Professor)

Jonathan D'Angelo (PhD. Student)

Muhammad Farhan (PhD. Student)

Muhammad Khan (PhD. Student)

Nuraddin Matchanov (Visiting Research Associate)

Chun-I Wu (Visiting Research Associate)

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Our main areas of research are thermoelectrics and surface enhanced Raman spectroscopy (SERS). 
Our developed measurement systems and capabilities are listed here.
Researchers in our group are shown below.
Hogan's Heroes
This research of thermoelectrics for shipboard applications is sponsored by the Science and Technology Division of the Office of Naval Research under Program Officer Dr. Mihal Gross.

Thermoelectric devices can used for cooling applications, or for power generation applications.  If electrical energy is supplied to the thermoelectric module it will create a thermal gradient across the device.  The direction of the thermal gradient can be reversed by changing the direction of current through the module.  Conversely, thermal energy can be supplied to a thermoelectric module and some of the heat flow through the module will be converted to electric power.  An introduction to thermoelectrics is given here.  We are working to increase the conversion efficiency of these power generation devices so that waste heat can be converted into electricity.
This research of thermoelectrics for the use on internal combustion engines for waste heat recovery is sponsored by the Department of Energy under Program Managers John Fairbanks, and Sam Taylor.
This research of thermoelectrics for waste heat recovery from mobile generators, battery recharging and waste reduction is sponsored by the Strategic Environmental Research and Development Program  under Program Officer Dr. John Hall.
Surface Enhanced Raman Spectroscopy (SERS)

The Raman effect was observed by CV Raman and KS Krishnan in 1928.  It consists of inelastic scattering of light from matter such that the frequency of the scattered light is shifted with respect to the incident light.  The energy difference between incident and scattered light is caused by changes in the vibrational state of the molecules the light interacts with.

Raman scattering is an inherently weak effect with only approximately one in a billion photons exhibiting the Raman effect.  In 1970
Fleischmann, et al. reported a 5 to 6 magnitude increase in the Raman signal of the chemical pyridine when it was placed on a rough silver surface.  This enhancement in the Raman signal from surface roughening is now known to include two components: electromagnetic (~106 increase) caused by surface plasmon excitation, and chemical (~10-100 increase) caused by charge transfer between the metal and the chemical molecules.  One of the challenges in this field of study has been obtaining sensors that give relatively uniform enhancement factors over the detector.  Often "hot spots" are found where sizable enhancements of the Raman signal are found, however these spots can be few and difficult to locate.

We are using GeO
2 nanowires, and ZnO nanowires as substrates that we coat with gold.  The gold forms nanometer sized droplets on these nanowires, and SERS enhancement factors of approximately 106 have been measured with a ±20% variation over the substrate.
This research is sponsored by the National Science Foundation {Electrical, Communications and Cyber Systems(ECCS)}.
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