ELECTRONIC
MATERIALS & PULSED LASER DEPOSITION
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)
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.
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.
Thermoelectrics
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.
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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 GeO2
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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