Nanoscience
and Technology
Research
Thrusts
.... .Nanostructures
.... .Biomimetics
..... Bio-Nano
Nanoscience Research in the Physics Department
- BIO-NANO PHYSICS:
- Probes of Protein Folding
(Steve Hagen): The mechanism by which proteins fold is still
largely a mystery. This problem has taken on increasing importance
because now there are diseases that have clearly been linked to
errors in the protein folding mechanism. Steve Hagen is studying
protein folding using nano-scale capillaries. The strain created
by flowing through such a narrow orifice causes the proteins to
change configuration, which can be detected optically. His work
provides a window in real time how proteins fold.
Funding:
National Science Foundation: Dynamics of Polypeptide Diffusion and Collapse - $100K/year.
NIH: Novel Inhibitors of Fungal Aspartic Proteinases - $57K/year.
- Nanoscale In-vivo Probes of Plant Cells
(Mark Meisel): A fundamental problem with long distance space
exploration is the ability to grow plants in a zero gravity environment.
Prof. Meisel and coworkers in IFAS have magnetically levitated plants
to see the effects of zero gravity. They found that the plants become
stressed in their experiments and this has been linked to the large
magnetic fields they apply, which are five times larger than in
a hospital MRI apparatus. As part of the nanoscience proposal to
DOE, they mark individual genes with fluorescent dye and are able
to see how the plants are stressed in a magnetic field from inside
the plant on a nanometer scale.
Funding:
NSF (NHMFL In-House-Science Program) - Low Gravity Plant Growth Experiments Using High Magnetic Field Gradient Levitation.
- Probes of Protein Folding
(Steve Hagen): The mechanism by which proteins fold is still
largely a mystery. This problem has taken on increasing importance
because now there are diseases that have clearly been linked to
errors in the protein folding mechanism. Steve Hagen is studying
protein folding using nano-scale capillaries. The strain created
by flowing through such a narrow orifice causes the proteins to
change configuration, which can be detected optically. His work
provides a window in real time how proteins fold.
- NANO-MAGNETS/SPINS:
- Dynamics of Nanoscale Magnets (Steve
Hill, Mark Meisel): More and more information is put on computer
hard drives by increasing the density (reducing the size) of magnetic
bits. If the bits become small enough, they become superparamagnetic
and do not retain their information content. How to overcome this
limitation is the central problem of the magnetic industry. Steve
Hill, George Christou (Chemistry) and coworkers, in a NSF funded
NIRT proposal, are studying the dynamics of tiny magnetic molecules
- the smallest known man made magnets. From electron spin resonance
studies, they aim to better understand how magnetic bits flip and
how to suppress superparamagnetism, allowing far greater information
density storage than at present. Unraveling the quantum behavior
of these bits may also lead to new applications such as quantum
computers.
Funding:
NSF (Hill): Quantum Effects In Single Molecule Magnets - $110K/year.
NSF (Hill): Electron Magnetic Resonance Investigations Of Low Dimensional Conductors And Superconductors - $75K/year
Am. Chemical. Society (Meisel): Synthesis and Characterization of Novel Spin Ladder Materials - $60K.
NSF (Meisel): Characterization of Novel Low Dimensional Magnetic Systems - $42K.
NSF(Meisel): Acquisition of Variable Temperature and Magnetic Field Magnetometer for Nanoscience Research and Education - $133K.
- Nanoscale Applications of New Spintronics
Materials (Art Hebard): A collaboration between Physics
(Hebard) and MSE (Abernathy and Pearton) has led to the exciting
discovery of room temperature ferromagnetism in the diluted magnetic
semiconductors (Ga, Mn)P and Ga,Mn)N. Controlling and manipulating
electron spin at the nanoscale in these new "spintronics"
materials should enable a new generation of magnetoelectronic devices
for non-volatile memories, high speed information processing, and
quantum computing. Electric field gated ferromagnetism and the use
of tunnel injection for spin filtering are among the ambitious goals
of this effort.
A full MRSEC proposal has recently been submitted to the NSF. Physics Faculty on the MRSEC Proposal are: Art Hebard, David Tanner, Selman Hirschfeld, Dmitrii Maslov, Chris Stanton, Andrew Rinzler, Mark Meisel.
Funding:
US Air Force: Nanoscale Devices & Novel Engineered Materials - ~75K/year.
NSF: In Situ Characterization Of Electrical And Optical Properties Of Air-Sensitive Ultra-Thin Films And Thin-Film Interfaces - ~$110K/year.
Am. Chemical Society: C60 Adsorption On Metal Surfaces - Physics And Chemistry Of Interfacial Charge Transfer - $60K.
- Dynamics of Nanoscale Magnets (Steve
Hill, Mark Meisel): More and more information is put on computer
hard drives by increasing the density (reducing the size) of magnetic
bits. If the bits become small enough, they become superparamagnetic
and do not retain their information content. How to overcome this
limitation is the central problem of the magnetic industry. Steve
Hill, George Christou (Chemistry) and coworkers, in a NSF funded
NIRT proposal, are studying the dynamics of tiny magnetic molecules
- the smallest known man made magnets. From electron spin resonance
studies, they aim to better understand how magnetic bits flip and
how to suppress superparamagnetism, allowing far greater information
density storage than at present. Unraveling the quantum behavior
of these bits may also lead to new applications such as quantum
computers.
- NANO PHYSICS at SURFACES and INTERFACES:
- Low Temperature Scanning Tunneling Microscope
(Yoonseok Lee): Although scanning tunneling microscopes (STM)
and atomic force microscopes (AFM) have become ubiquitous, there
are very few low temperature microscopes in operation around the
world. Yet low temperature STM's have the ability for detailed spectroscopy
of the electronic structure of materials and to move individual
atoms to precise positions. Yoonseok Lee, a new hire in the Physics
department, is going to build a low temperature STM as part of his
start-up in order to study nanostructures and reduced dimensionality
molecules and compounds.
- Scanning Proton Microprobe (Henri
Van Rinsvelt, Gene Dunnam)- The scanning proton microprobe is
essentially an analytical high energy ( 2.5 MeV ) proton probe produced
by magnetic focusing of the beam from an electrostatic particle
accelerator. At this time, analytical and structural information
can be extracted at the part per million level with a 500 nm spatial
resolution. Typical applications include:
- Three-dimensional maskless micro-machining
of components for MEMS devices and photonic devices.
- Applications to the life sciences, such
as the elemental distribution at the single cell level.
- Material sciences investigations of
segregation, diffusion, impurity, defect, and composition
- Environmental pollution studies including
toxic element speciation.
- Geological investigations such as the
correlation between trace elements in core samples and historical
climatic data.
- Applications to the arts, archeology, and criminology in the investigation of the authenticity of old paintings, manuscripts, artifacts, and fossils, and the analysis of crime evidence.
- Three-dimensional maskless micro-machining
of components for MEMS devices and photonic devices.
- Low Temperature Scanning Tunneling Microscope
(Yoonseok Lee): Although scanning tunneling microscopes (STM)
and atomic force microscopes (AFM) have become ubiquitous, there
are very few low temperature microscopes in operation around the
world. Yet low temperature STM's have the ability for detailed spectroscopy
of the electronic structure of materials and to move individual
atoms to precise positions. Yoonseok Lee, a new hire in the Physics
department, is going to build a low temperature STM as part of his
start-up in order to study nanostructures and reduced dimensionality
molecules and compounds.
- NANOSCALE STRUCTURES
- Carbon nanotubes (Andrew Rinzler)
for reasons of mechanical strength, chemical stability and the availability
of both metallic and semiconducting variants, have emerged as the
material most likely to make molecular scale electronics, orders
of magnitude smaller than present day microelectronics, with concomitant
increases in speed and power, a reality. Already, in the Department
of Physics at UF, we are investigating the interfacing of carbon
nanotubes with microelectronic systems for the development of new
devices ranging from ultra small anemometers (needed for development
of the next generation supersonic fighter aircraft), ultra-fast
chemical sensors (for 100% monitoring of high traffic areas), and
Terahertz radiation detectors (a large, remaining, uncharted region
of the electromagnetic spectrum). Figure 1 shows the basis of these
devices, nanotubes pinned on their ends by gold electrodes, tethered
across deep trenches micro-machined in a silicon substrate.
Carbon nanotubes will also revolutionize nanoscale probe techniques. Figure 2 shows a multi-wall carbon nanotube mounted on a standard atomic force microscopy tip. The structure has been coated with a polymer and the tip of the nanotube has been exposed by a focused laser beam. The polymer provides robust attachment to the tip and electrically insulates all but the end of the nanotube. Beyond allowing in-vivo imaging of cellular structures of unprecedented resolution, this research may lead to the development of nanoscale bioelectrodes useful in nerve replacement therapies. These structures will also be used in the development of a nanoscale thermal sensor having potential applications in monitoring local energy consumption in sub-cellular processes.
Figure 1- Tethered nanotube device Figure 2 - Nanotube bio-nanoelectrode
Funding:
Honeywell: Artificial Muscle Arrays - ~$100K/year.
US Army: Materials And Devices For Optical Sources And Protection Of Optical Sensors - ~$200K/year
NSF: Construction Of A Nanotube Tip Mounting Workbench For Generation Of Nanoscale Probes - $90K.
- Carbon nanotubes (Andrew Rinzler)
for reasons of mechanical strength, chemical stability and the availability
of both metallic and semiconducting variants, have emerged as the
material most likely to make molecular scale electronics, orders
of magnitude smaller than present day microelectronics, with concomitant
increases in speed and power, a reality. Already, in the Department
of Physics at UF, we are investigating the interfacing of carbon
nanotubes with microelectronic systems for the development of new
devices ranging from ultra small anemometers (needed for development
of the next generation supersonic fighter aircraft), ultra-fast
chemical sensors (for 100% monitoring of high traffic areas), and
Terahertz radiation detectors (a large, remaining, uncharted region
of the electromagnetic spectrum). Figure 1 shows the basis of these
devices, nanotubes pinned on their ends by gold electrodes, tethered
across deep trenches micro-machined in a silicon substrate.
- THEORETICAL AND COMPUTATIONAL NANOSCIENCE (QTP: Trickey, Cheng and CMT Kumar, Maslov, Ingersent, Dorsey, Hershfield, Hirschfeld, Muttalib, Obhukov, Stanton): All the above are experimental probes on the nanoscale. The largest number of researchers on campus studying theoretical nanoscience is in the New Physics Building in the Quantum Theory Project and the Condensed Matter Theory groups. They are working on many projects including: 1) modeling the structure of molecules and solids, 2) performing technologically important investigations as searching through millions and millions of atomic configurations in magnetic multilayers to optimize the magnetoresistance, 3) Electronic, optical and transport properties of reduced dimensional semiconductor nanostructures, 4) thermal conductivity in nanowires, 4) properties of dilute magnetic semiconductors, 5) metal-insulator transitions in reduced dimensional systems, 5) quantum hall effect.. This theoretical effort complements the above experimental effort. It is important remember that all the funded Nanoscience and Engineering Centers (NSEC) last year had strong theoretical components.
Physics Resources
Major Equipment for NanoScience Research Currently in Physics Laboratories:
- Nanotube Mounting Workbench for
mounting carbon nanotubes on atomic force microscopy cantilevers (see
Figure 2, above).
- CVD nanotube growth system.
- Nanotube purification system.
- Renishaw Micro-Raman spectrometer
(Kr ion (647.1 nm) and Nd-YAG (532 nm) laser excitation).
- Perkin-Elmer 900 UV-Vis-NIR spectrophotometer
(185 nm - 3300 nm range)
- Diffusion pumped general-purpose evaporation
station (base pressure of 1.5E-7 Torr) equipped with a multiple
source carousel for resistively heated depositions. The system includes,
multiple shutters, a thickness monitor, a rotating substrate holder
which can be tilted through an angle of 270 degrees, a 2.5 cm CommonWealth
ion source which can be configured either for substrate cleaning or
deposition, and a dc glow discharge ring for growing tunnel-junction
oxides or removing photoresist residues.
- Load locked, turbopumped, thin-film deposition
system (two sputtering stations DC and RF magnetron, one resistive
evaporation station).
- Turbo-pumped ion beam deposition system
(base pressure of 3.0E-6 Torr) dedicated to reactive ion beam sputter
deposition of transparent conducting In/InOx films.
- Diffusion-pumped all stainless steel vacuum
system (base pressure of 1.5E-8 Torr) for multiple-source evaporations
of metals from thermally regulated crucibles. The system includes multiple
shuttering, a nitrogen-cooled substrate holder, and an in situ mask
changing capability which will allow three different masks to be placed
in close proximity to the sample without breaking vacuum or disturbing
the electrical contacts for the in situ transport measurements
- Cyro-pumped three station ion-beam system
(base pressure of 1.5E-6 Torr). Two of the ion guns are directed at
two different target carousels, each of which can hold two targets.
The third gun is directed at the substrate and can be used for cleaning
or ion-assist processing.
- SHIVA vacuum/deposition system
for in situ deposition and characterization at low temperatures (1.5-300K)
and high fields (0-7T) of air-sensitive thin films.
- Quantum Design Physical Properties Measurement
System (PPMS). Provides a stable temperature (1.8-400K) and
magnetic field (7T) platform in a one-inch diameter modular space. The
system also includes a horizontal sample rotation stage and instrumentation
for ac measurements of resistivity, Hall, critical current, and I-V
measurements.
- Variable temperature flow cryostat with
controller.
- ThermoMicroscopes scanning probe microscope
with CP Research Head for ex situ characterization of topography (AFM)
and surface electric potentials (EFM).
- Digital Instruments MultiMode scanning
probe microscope.
- Solartron Model 1260 Impedance Analyzer
with four terminal measurement capability extending from 1mHz to 32MHz.
- Linear Research Model LR-700 AC Bridge
has state of the art low noise performance.
- Miscellaneous electronics including Lock-In amplifiers, voltmeters, signal generators, multimeters, current and voltage amplifiers, an electrometer, a source measure unit, and a spectrum analyzer.
- Eight computers fully equipped with LabView and interconnected to
the central physics computers.
Other Resources in the New Physics
Building:
- Professor David Tanner's group - visible/IR
reflection and transmission.
- A Class 5000, UV safe clean room for photolithography
with 3 class 100 workstations, Mask Aligner, Photoresist spinner, wet
bench, ovens and inspection microscopes.
- The services of the departmental machine shop
staffed with five full-time machinists and an electronics shop staffed
with three full-time repair technicians are readily available.
- A diffusion-pumped general-purpose evaporator
set up in a common use facility.
- Access to a shared Quantum Design SQUID
magnetometer.
- Computational Tools including
Proposed New Equipment for Nanolithography (to be housed
in NPB):
- E-beam writer
- Focused ion beam system
- Deep ultraviolet exposure system
- Sputter deposition system
- Reactive ion etch system
- Expanded clean room facility
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