Why Nano now

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Why Nano now?
What has enabled Nanoscience?
An incomplete list . . . .

• Advances in Computing Power
• New Generation of Scientific Instruments
• Scanning Probe Microscopes

Scanning Tunneling Mic. (STM) Atomic Force Mic.
(AFM) Magnetic Force Mic. (MFM) Near Field
Scanning Optical Mic. (NSOM)
Very Sharp Tip scans over sample surface
ATOMIC RESOLUTION
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Scanning Probe Microscopy

• SCANNING TUNNELING MICROSCOPE (STM) First SPM
  1983. The Since then, many types of SPM
• ATOMIC FORCE MICROSCOPY (AFM, also known as
  scanning force microscopy)
• MAGNETIC FORCE MICRSCOPY (MFM)
• near field scanning optical microscopy (NSOM)
• Others .

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Scanning Probe Mic Sharp tip
Sharp tip moves over surface and measures some
property
Scanning Probe Tip
Sample
Sample
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STM, Nobel Prize 1986
Binnig and Rohrer
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STM, Imaging
- Battery
Current
Tunneling Current
Sample
Sample
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STM images, Examples
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STM Images, Eigler 1
Don Eigler, IBM
Eigler et al. NATURE 363, 1993
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STM Images, Eigler 2
Don Eigler, IBM
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STM Images, Wilson Ho 1
Wilson Ho, UC Irvine
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STM Images, Wilson Ho 2
Wilson Ho, UC Irvine
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Handmaking Molecules! Wilson Ho 3
Wilson Ho UC, Irvine.
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Atomic Force Microscopy
LASER
LASER Detector
Computer
Mirror
Microscope Tip
Display
Sample Surface scanned back and forth
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• A Thermo Microscopes Explorer AFM

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AFM tips
Made from Si or Si3N4
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Carbon nanotubes
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AFM images Materials
This montage of atomic force microscope images
above shows the (0001) growth surface of a 6H-SiC
crystal grown by physical vapor transport. The
single steps on the surface are each 15.2
Angstroms high, the lattice parameter along
0001. Carnegie Mellon University Material
Science and Engineering
Pittsburgh, PA, USA
http//neon.mems.cmu.edu/rohrer
/rohrer.html
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AFM imagesBiological Samples
The image shows human eurythrocytes, or red blood
cells, imaged in a buffer solution. The shape of
the cell is important to its function. Atomic
force microscopy can be used to identify the
unique characteristics of the cell shape and
size. Luana Scheffer Tel-Aviv University School
of Medicine/Department of Physiology Tel-Aviv,
Israel
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Images and Manipulation of DNA !
Departmento Física de la Materia Condensada UAM
Asylum Research
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Pulling on Biological Fibers
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More than topography
Topography
Hardness
Visco-elasticity
Simultaneous C-AFM images of carbon fiber-epoxy
composite used in aircraft manufacturing,
acquired simultaneously in topography (left),
force modulation (center), and phase detection
(right), modes. The force modulation image
(center) shows the harder (brighter) carbon fiber
in the darker colored epoxy matrix. The phase
image (right), shows similar image contrast, and
shows differences in the visco-elasticity or
"stickiness" across the fiber.
Field of view 15 µm.
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AFM images Carbon Nanotubes
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AFM images Adenovirus
Viral DNA
Atsuko Negishi UNC Mat. Sci.
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AFM, (sub)atomic resolution
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Titin unfolding
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Titin
http//www.ks.uiuc.edu/Research/smd_imd/titin/
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Pulling Titin 2
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Pulling Titin 3
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AFM feedback
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Contact Mode
DC deflection maintained by feedback loop
Deflection Force
Piezoelectric translators
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Non-Contact and Tapping Mode
Amplitude maintained by feedback loop
Amplitude Force
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Interaction Potential
Energy
Tip Sample separation
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Resolution and Artifacts
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Tip Shape Effects
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LEGO Atomic Force Microscope