Transcript nanoworld-to-real-wo..

From the Nanoworld to the
Real World: Using
Nanoscience to Teach
Leigh M. Smith
Department of Physics
University of Cincinnati
www.physics.uc.edu/~smithl
Financially supported by the National Science Foundation (0806700 and 0701703) The
Institute for Nanoscale Science and Technology at the University of Cincinnati, the
Nano-Biotechnology Initiative at Ohio University and the Australian Research
Council.
Outline
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What is nanoscience?
Is it really a scientific revolution?
Understanding quantum dots..
Quantum Mechanics and Music
Quantum tunneling and an STM
Electrons really are waves after all
Applications
Controlling electron waves…
Cadmium Selenide (CdSe)
Quantum Dots
1 nm
5 nm
•Same material (CdSe), different colors!
Controlling electron densities
Gold nanoparticles?
Naomi Halas, Rice
Shaelev, Purdue
Controlling light waves
Silica – Quartz – SiO2
Opals – (Silica)
Biology does it all the time..
Joe Haus, University of Dayton
Change the index of the pores and
the reflected color changes…
Tayeb et al, Optics and Photonics News, Feb. 2003
Photonic Band Gap Materials
Synthetic 3D photonic band gap materials
Opals – Silica Spheres
But is it a revolution?
• Thomas Kuhn, “The structure of scientific
revolutions”
• “Normal” Science
• Model of Nature
• Test-test-test-test-test
• Crisis
• New measurement tools or techniques
• Paradigm Shift
• Re-write the textbooks!
• Not just New Tools but we are now creating New
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Structures in Nature itself
The way we are doing science is changing!
Breakdown of the division between disciplines
Whither Quantum Dots?
• The origins of quantum mechanics
Black Body Spectrum
• The spectrum and
intensity of
electromagnetic
waves from a
black body
depend only on its
temperature
Atomic Spectra
Helium
Hydrogen
Neon
Atoms emit in very narrow bands of light…and the colors emitted are
singular signatures of the atoms involved
Rutheford alpha particle
scattering
Using undergraduates as slave
labor
• In 1909, an undergraduate, Ernest Marsden, was being trained by
Geiger. To quote Rutherford (a lecture he gave much later):
• "I had observed the scattering of alpha-particles, and Dr. Geiger
in my laboratory had examined it in detail. He found, in thin
pieces of heavy metal, that the scattering was usually small, of
the order of one degree. One day Geiger came to me and said,
"Don't you think that young Marsden, whom I am training in
radioactive methods, ought to begin a small research?" Now I
had thought that, too, so I said, " Why not let him see if any alphaparticles can be scattered through a large angle?" I may tell you
in confidence that I did not believe that they would be, since we
knew the alpha-particle was a very fast, massive particle with a
great deal of energy, and you could show that if the scattering
was due to the accumulated effect of a number of small
scatterings, the chance of an alpha-particle's being scattered
backward was very small. Then I remember two or three days
later Geiger coming to me in great excitement and saying "We
have been able to get some of the alpha-particles coming
backward …" It was quite the most incredible event that ever
happened to me in my life. It was almost as incredible as if you
fired a 15-inch shell at a piece of tissue paper and it came back
and hit you."
Result….
http://abyss.uoregon.edu/~js/cosmo/lectures/lec08.html
The Bohr Model
http://abyss.uoregon.edu/~js/cosmo/lectures/lec08.html
Electrons as waves….
• Prince Louis de Broglie was a member of
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an illustrious family, prominent in politics
and the military since the 1600's. Louis
began his university studies with history,
but his elder brother Maurice studied xrays in his own laboratory, and Louis
became interested in physics. He worked
with the very new radio telegraphy during
the war (World War I).
The only PhD Thesis which won a Nobel
Prize
The Music of Quantum
Mechanics…
http://www.youtube.com/watch?v=fN4fIRjMf-M
http://www.youtube.com/watch?v=iUDNQfePKlQ
http://www.nytimes.com/2006/08/27/arts/television/27heff.html
http://www.youtube.com/watch?v=owAj5LiXG5w
Waves on a string
f=
l=
L
f1
2f1
3f1
4f1
2L/1
2L/2
2L/3
2L/4
Idea was quite simple
•Radiation pressure p = E/c
•Planck’s E = hf, v = fl
•p = E/c = hf/c = h/l
• l = h/p
•Can explain atomic spectra!
A prince comes to the rescue!
Prince Louis-Victor Pierre Raymond deBroglie
Planck says E = h f = h c/l
But Einstein says that E/c = p
So then E/c = h/l  l = h/p
Davisson-Germer Expt.
The origin of electron microscopes!
A particle in a box…
“Seeing” quantum confinement
1.9 nm

5.2 nm
The Scanning Tunneling
Microscope
• Quantum tunneling and seeing
atoms
"Figure: Michael Schmid, TU Wien"
http://phet.colorado.edu/simulations/quantum-tunneling/quantum-tunneling.jnlp
•Now there is
no doubt at all
that electrons
are waves!
Assembling 48 iron atoms on copper
The quantum corral
Atomic art…
Applications of Nanoscience
Making CdSe QDs Bio-compatible
Klimov, Los Alamos Science
(2003)
Development of Frog Embryo
Animal/Organ Visualization
Cancer Resection - Biopsy
Summary and Conclusions
• Nanoscience is the fabrication and
study of objects ~1 to 100 nm.
• Things change when you get that
small  quantum mechanics
• Vast new opportunities for designing
materials for new purposes!
Good web sites
• Nanoscale Informal Science Education (NISE) Network
• http://www.nisenet.org/
• National Center for Learning and Teaching in Nanoscale
Science and Engineering (NCLT)
• http://www.nanoed.org/
• “When Things Get Small”: 30 min. TV show, 5 Emmy
Awards!
• http://www.uctv.tv/getsmall/
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“There’s Plenty of Room at the Bottom”, Feynman’s
lecture from 1959
• http://www.zyvex.com/nanotech/feynman.html
• Science in Motion (Pennsylvania)
• http://www.science-in-motion.org/
• Profile of Naomi Halas
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http://www.pbs.org/wgbh/nova/sciencenow/3209/03.html