SATURDAY MORNING PHYSICS – SPRING 2011
February 18, 2011
Let’s Get Small
Chris Hughes
Scott Paulson
Costel Constantin
What is a nanometer?
This is a flea on Murray.
A flea is about 1
millimeter in size.
1000 times
smaller
This is Murray. Murray is
about 1 meter in size
Why study nanophysics?
Fleas (and all
living things)
are made of
cells. A
typical cell is
about 1
micron in size
1000 times
smaller
1000 times
smaller
Inside cells
we find
Recent breakthroughs allow us to not only study, but also
DNA. DNA
CREATE (see the 10 micron long “nanoguitar”, with 50 nm wide
is, about 1
strings!) objects at the nanometer scale. At this size we find that nanometer
systems behave very different from their macroscopic
across (but
counterparts, and this will lead to exciting new technologies.
can be very
JMU’s nanoscience laboratories house state of the art facilities
where students can create and study a wide variety of systems at long!)
this length scale!
Material Properties: Continuum
• Measure Bulk Properties
• Electrical (Resistivity)
• Mechanical (Strength)
• Thermal (melting point)
• Optical (color)
Material Properties: Atoms
Electron Density of C60
Hydrogen Spectrum
What is Nano?
Study of structure
where at least 1 and
usually 2-3 dimensions
are 1~100 nanometers
in size
Fluorescence of CdSe Nanocrystals
Why is Nanoscience Different?
Strength and Composites
Why is Nanoscience Different
Electronics
Why is Nanoscience Different
Chemistry (and Thermal)
Why is Nanoscience Different
Chemistry (and Thermal)
Why is Nanoscience Different
Chemistry
• Number of atoms on surface?
– Proportional to r2
• Number of atoms in volume?
– Proportional to r3 as
• Reactivity depends on ratio of surface/volume
– Proportional to r2/r3 = 1/r
– The smaller the sample the bigger surface/volume
Why Now?
Atomic Force Microscopy
Tools of the trade
What Can Nanoscience Do?
Lighter, more agile, fly longer
without refuel, hovers,
smaller, gather more
information (superior
sensors).
1947- 100 Transistors
2004-108 Transistors
More is Different!
Imitating Nature
• Nature creates useful
structures at the
nanoscale all the time.
Nacre is 3000x stronger than the aragonite
it is made of…how?
Red Abalone
Nudelman, F.; Gotliv, B. A.; Addadi, L.; Weiner, S. (2006).
"Mollusk shell formation: Mapping the distribution of
organic matrix components underlying a single aragonitic
tablet in nacre". Journal of Structural Biology 153 (2): 176.
Imitating Nature
Kalpana S. Katti, Dinesh R. Katti and Bedabibhas Mohanty (2010).
“Biomimetic Lessons Learnt from Nacre”, in Biomimetics Learning from
Nature, Amitava Mukherjee (Ed.), ISBN: 978-953-307-025-4, InTech,
Available from: http://www.intechopen.com/articles/show/title/biomimeticlessons-learnt-from-nacre
DNA
• Nature’s most important polymer
DNA Origami
• Because of the
complementarity of DNA, it
can be used as a scaffold to
self-assemble structures on the
nano-scale.
DNA Origami
•
Top row, folding paths. a, square; b, rectangle; c, star; d, disk with three holes; e, triangle with rectangular domains; f, sharp triangle with trapezoidal domains
and bridges between them (red lines in inset). Dangling curves and loops represent unfolded sequence. Second row from top, diagrams showing the bend of
helices at crossovers (where helices touch) and away from crossovers (where helices bend apart). Colour indicates the base-pair index along the folding path; red
is the 1st base, purple the 7,000th. Bottom two rows, AFM images. White lines and arrows indicate blunt-end stacking. White brackets in a mark the height of an
unstretched square and that of a square stretched vertically (by a factor >1.5) into an hourglass. White features in f are hairpins; the triangle is labelled as in Fig.
3k but lies face down. All images and panels without scale bars are the same size, 165 nm 165 nm. Scale bars for lower AFM images: b, 1 m; c–f, 100 nm.
Folding DNA to create nanoscale shapes and patternsPaul W. K.
RothemundNature 440, 297-302 (16 March
2006)doi:10.1038/nature04586
DNA Origami
•
a, Model for a pattern representing DNA, rendered using hairpins on a rectangle (Fig. 2b). b, AFM image. One pixelated DNA turn (100 nm) is 30 the size of an actual DNA turn (3.6 nm)
and the helix appears continuous when rectangles stack appropriately. Letters are 30 nm high, only 6 larger than those written using STM in ref. 3; 50 billion copies rather than 1 were
formed. c, d, Model and AFM image, respectively, for a hexagonal pattern that highlights the nearly hexagonal pixel lattice used in a–i. e–i, Map of the western hemisphere, scale 1:2
1014, on a rectangle of different aspect ratio. Normally such rectangles aggregate (h) but 4-T loops or tails on edges (white lines in e) greatly decrease stacking (i). j–m, Two labellings of
the sharp triangle show that each edge may be distinguished. In j–u, pixels fall on a rectilinear lattice. n–u, Combination of sharp triangles into hexagons (n, p, q) or lattices (o, r–u).
Diagrams (n, o) show positions at which staples are extended (coloured protrusions) to match complementary single-stranded regions of the scaffold (coloured holes). Models (p, r)
permit comparison with data (q, s). The largest lattice observed comprises only 30 triangles (t). u shows close association of triangles (and some breakage). d and f were stretched and
sheared to correct for AFM drift. Scale bars: h, i, 1 m; q, s–u, 100 nm.
Folding DNA to create nanoscale shapes and patternsPaul W. K.
RothemundNature 440, 297-302 (16 March
2006)doi:10.1038/nature04586
Toward Better Circuits?
• Working with the
CalTech group,
researchers at IBM
Almaden Res.
Center are
developing ways of
using DNA selfassembled
structures as
templates for
microelectronics.
http://www-03.ibm.com/press/us/en/pressrelease/28185.wss
DNA Origami
• From
http://www.physics.ox.ac.uk/biophysics/turbe
rfield/images/tetrahedron.jpg
NanoDays/Making Stuff
When: 1-4 pm, on March 27th.
Where: Explore More Discovery Museum, Harrisonburg VA.
Local high school educators, JMU Nanotechnology faculty,
and the Explore More Discovery Museum are partnering for
the first annual NanoDays Celebration.
NanoDays celebrations will combine simple hands-on activities for children with events exploring current research
for adults.
NanoDays activities demonstrate different, unexpected properties of materials at the nanoscale
-- sand that won’t get wet even under water, water that won’t spill from a teacup, and colors that depend upon
particle size. There will also be a microscope that allows you to "feel" the surface of materials on the nanoscale.