Physics Graduate Projects at UT Space Institute

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Physics Graduate Projects at UT Space Institute

• Professor Horace Crater
• Professor Lloyd Davis
• Associate Professor Christian Parigger
• Research Assistant Professor Ying Ling Chen
• Emeritus Professor Jim Lewis
• Adjunct Professor Charles Johnson
• Center for Laser Applications
• www.utsi.edu/ldavis ldavis_at_utsi.edu

UTSI
Physics 599 seminar class UT Knoxville, November
11, 2009
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University of Tennessee Space Institute

• UTSI is a graduate campus of the UT Knoxville
• Graduate students may transfer between the
  campuses
• Students at UTSI obtain MS and PhD degrees from
  the University of Tennessee Knoxville
• Same degree requirements at UTSI and UTK
• UTSI has GRA positions, but no TA positions
• UTSI physics common practices
• PhD students have a committee member based in
  Knoxville
• Most students complete the MS degree en route to
  the PhD
• Some classes are offered at both campuses by
  interactive distance education
• Phys. 513, 514 606, 610, 643

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University of Tennessee Space Institute

• GRA and thesis/dissertation physics research
  opportunities are available
• with the Center for Laser Applications
• with research groups at the Air Force
  Arnold Engineering
  Development Center
• and in selected areas of theoretical particle
  physics
• Opportunities are also available for
  interdisciplinary research in Materials Science
• Solid state / materials physics

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Theoretical Particle Physics with Professor
Horace W. Crater

• Relativistic Two-Body Dirac Equations
• Meson Spectroscopy and Decays
• Bound and Scattering States in Quantum
  Electrodynamics
• Nucleon Nucleon Scattering
• Bound States in Quark-Gluon Plasma
• Relativistic N-Body Problem Plus Fields
• Electrodynamics, General Relativity
• Relativistic Center of Mass

Matthew Duran-MS Physics, 2007 Modeling the
ground-state Baryon octet using a generalization
of the Lagrange triangle solution
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Kyle Peterson-PhD Physics, December
2003 Computational magnetohydrodynamic
investigation of flux compression and implosion
dynamics in a Z-pinch plasma with an azimuthally
opposed magnetic field configuration electronic
resource Karen Norton-MS Physics, August
2006 Ultraviolet image analysis of spacecraft
exhaust plumes
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Jesse Labello - MS Physics, 2007 Characterization
of the temperature dependence of optical
components in the 10V cryo-vacuum chamber
Howard Frederick MS Physics,
2008 Experimental determination of emissivity
and resistivity of Yttria stabilized Zirconia at
high temperatures
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University of Tennessee Space Institute Center
for Laser Applications
CLA lab
Tennessee Higher Education Commission Center of
Excellence
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Laser Spectroscopy with
Professor Christian Parigger

• Laser-induced breakdown spectroscopy
• Atomic and molecular spectroscopy
• Computational
  modeling of
  
  laser breakdown
  phenomena

Pavlina J. Jeleva-PhD Physics, 2005 Photo-acousti
c analysis of dental materials and tissue
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Research Interests Professor Lloyd M. Davis

• Single-molecule spectroscopy, nanophotonics,
  biophotonics, biophysics, chemical physics
• Non-linear optics, quantum optics, ultrafast
  spectroscopy
• Femtosecond laser material and laser plasma
  interactions
• Numerical physics, Monte Carlo simulations

David Ball-PhD Physics, December
2006 Single-molecule detection with active
control

• Present position Postdoctoral fellow,
  Virginia
  Bioinformatics Center, 5-yr NIH funding

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Davis GRA Students (spring 08)

• Justin Crawford
• You Li
• Jason King
• James Germann
• Jesse Ogle (AEDC)
• Will Robinson
• Isaac Lescano (EE)

Larissa Wenren
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Outreach OSA student chapter
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Single-molecule detection in solution was first
achieved
by using pulsed laser excitation and time-gated
photon counting to reject the Raman scatter that
overlaps the fluorescence band
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Maximum likelihood data analysis
Measurements with small numbers of photons Eg.,
Fluorescence Lifetime of a single molecule
Find ? such that Prob(Data ? ) is a maximum
Error in lifetime ? ? ? number of photons
Least-squares curve fitting fails because it
assumes a Gaussian distribution of errors
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Maximum-likelihood multi-channel photon-counting
microscopy
Justin Crawford
count-rate dependent time-walk
We have improved the sensitivity of time and
spectrally-resolved imaging for applications that
require resolving the signal contributions from
fluorescent species with overlapping spectra
NIH/NIBIB R03 grant
New MPD Modified Module
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High-throughput modular microfluidic systems for
drug discovery/development

• NIH R01-grant 2007-2011
• Collaborators Louisiana State University, Tulane
  University
• UTSI
• Develop of a set of ultra-sensitive near-infrared
  fluorescence readout methods for determining
  molecular species concentrations within plastic
  (PMMA) microfluidic devices
• Goal is to determine changes in enzyme activity
  in response to a library of 100,000 compounds
• Parallelized assays of enzyme activity with
  nanoliter samples by use of CCD camera
• Demonstrate the developed platform by searching
  for inhibitors of L1-endonuclease, an enzyme
  implicated in cancer

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Use of diode laser for detection of near-infrared
phthalocyanine dyes
You Li
Raman notch transmission
We are developing custom instrumentation for
ultrasensitive detection of deep-red fluorophores
for application to pharmaceutical drug screening
within PMMA microfluidic devices.
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You Li Photon bursts from single near-ir dye
molecules
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Single Protein Studies
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Single-molecule detection in a nanochannel

• Goal
• To detect and trap single molecules of
  fluorescently-labeled proteins in solution with
  high photon count rate for studies of protein
  interactions and conformational changes with time
  resolution of tens of microseconds
• Approach
• Confocal fluorescence microscope
• Confine molecules in nanofluidic channel
• Custom electronics to actively
  control
  electrokinetic transport
  
  for positioning each molecule in
  confocal
  volume
• Excite fluorophore to saturation
  using intense
  laser
• Replace molecule after bleaching

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Nanofluidics fabrication strategies

• Approach 1 EBL/RIE Nanochannels and Bonding
• Electron Beam Lithography
• Photolithography
• Bonding with Fused-Silica
• Approach 2 Sacrificial Nanochannels and Bonding
• Electron Beam Lithography
• Wet Etching of Sacrificial Lines
• Approach 3 FIB Machining and Bonding
• Focused Ion Beam
• Bonding with Fused-Silica
• Approach 4 Femtosecond Laser Direct Writing
• High-Aspect Vertical Nanoholes
• Possibility of enhanced light collection from
  
  a single molecule in a vertical nanochannel

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Single microjoule femtosecond laser-pulse
fabrication of 10-micron deep nano-holes
photodiode
ultrafast mirror
3D piezo

• Nikon CF Plan Achromat 79173
• 150 mm conjugate
• Dry, NA 0.85, WD 0.410.45 mm
• cc for 0.110.22 mm, n 1.52

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Depth measure by SEM/FIB sectioning
Cross-section near top of holes

• Use of the DualBeam? SEM/FIB tool, CNMS, ORNL
• Diameters of 200-500 nm and depths exceeding 11
  micron

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Possible mechanisms for high aspect holes

• Creation of similar long features internal to the
  material has been attributed to
• self-focusing due to Kerr nonlinearity of fused
  silica EN Glezer E Mazur, Appl. Phys. Lett.
  71, 882884 (1997)
• interface-induced spherical aberration
  self-focusing
  Q Sun, et
  al., J. Opt. A Pure Appl. Opt. 7, 655659
  (2005)
• long features only when gt 20 µm from the surface
• Focusing with spherical aberration
• objective correction collar for 0.110.22 mm, n
  1.52

Air SiO2
cc.17
Zemax
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Possible mechanisms for high aspect holes

• Creation of similar long features internal to the
  material has been attributed to
• self-focusing due to Kerr nonlinearity of fused
  silica EN Glezer E
  Mazur, Appl. Phys. Lett. 71, 882884 (1997)
• interface-induced spherical aberration
  self-focusing
  Q Sun, et
  al., J. Opt. A Pure Appl. Opt. 7, 655659
  (2005)
• long features only when gt 20 µm from the surface
• Focusing with spherical aberration
• objective correction collar for 0.110.22 mm, n
  1.52

Zemax
Single-pulse ultrafast-laser machining of high
aspect nano-holes at the surface of SiO2,
YV White X Li Z Sikorski LM Davis W
Hofmeister, Optics Express 16, 1441114420 (2008).
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Nanofluidic device fabrication
microchannels
4 inch, 500 mm SiO2 wafer
UV
nanochannels
coat 3 mm
e-beam
exposure
UV resist
exposure
develop
PMMA
50 nm
etch
develop
chrome
50 nm
reactive ion etch
SiO2
etch
cleaning CO2 laser hole punching wafer
dicing cleaning cover slip bonding
reactive ion etch ? PMMA removed
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Bonding of patterned chips
To avoid nanochannel collapse Low temperature
bonding lt100 ?C Surface cleaning in HF
solution Pressure1MPa Bonding time 12 hours
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SEM characterization of nanochannels
Dual Beam FIB/SEM
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Assembled nanofluidic device
electrodes
Plexiglass housing
nanofluidic chip
aluminum base
laser
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1-D trap in a nanochannel
Irradiance profile

• Molecules are confined to 1-D within 100 nm
  nanochannel
• Two displaced laser beam foci pulse-interleaved
  excitation
• Irradiance at center constant
• Time-gated photon detection
• Electrophoretic/electro-osmotic motion along the
  nanochannel

V2
nanochannel
immersion fluid
V1
V
microscope objective
nanochannel
laser
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The Laboratory
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Control of electrokinetic voltage
nanofluidic device
sync
1.2 NA objective
beam dump
pump laser 76 MHz 608 nm two beams, each 30 mW
with 6.6 ns delay
filters
custom FPGA board
sliding mirror
I-MAX ICCD camera
pinhole
NI PCI-6602 counter / timer
SPAD
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Numerical simulations of single-molecule trapping
William N. Robinson
First molecule enters at 70.8 ms
Molecule photobleaches
Laser beam positions 0.3 µm
Expected duration of capture before bleaching
(?10?5)
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Fluorescence autocorrelation
15 s
Nanochannel freshly loaded with 0.6 pM
streptavidin/Alexa 610 in 0.2 PBS
active electrokinetic control
?10 V
0 V
FPGA voltages seen on oscilloscope during trapping
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Other ongoing projects

• Single-Molecule Trapping
• 1-D in nano-fluidic device
• 3-D in micro-fluidic device
• Single-Molecule Tracking

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4-Foci Fluorescence Microscope and Maximum
Likelihood Analysis
James Germann
Confocal microscope with 4 beams focused in
tetrahedon provides sub-micron position
trajectory information
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Microfluidic device for 3-D electrophoretic trap
Jason K. King
Platinum coated coverslip

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Configuration 2.5V, 10mA
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Further information

• Contact ldavis_at_utsi.edu