Transcript Tool of the Nanosciences

Tools of the Nanosciences
• There’s plenty of room at the bottom
• It is my intention to offer a prize of $1,000 to the first guy
who can take the information on the page of a book and put
it on an area 1/25,000 smaller in linear scale in such
manner that it can be read by an electron microscope.
• another $1,000 to the first guy who makes an operating
electric motor---a rotating electric motor which can be
controlled from the outside and, not counting the lead-in
wires, is only 1/64 inch cube.
-Richard Feynman, 1960
Tools for Measuring Nanostuctures
• Scanning Probe Instruments
– Atomic Force Microscope (AFM)
– Scanning Tunneling Microscope (STM)
– Magnetic Force Microscope (MFM)
• Spectroscopy
• Electrochemistry
• Electron Microscopy
Atomic Force Microscopy
• Probe is nanoscale
dimensions, often
only a single atom in
size
• Electronics are used
to measure the force
exerted on the probe
tip as it moves along
the surface
Picture of MoO3 single crystal by an inter-atomic-force
microscopy
Scanning Tunneling Microscope
• The amount of
electrical current
flowing between a
scanning tip and a
surface is measured.
• Can be used either to
test the local
geometry or to
measure the local
electrical conducting
characteristics
Silicon atoms as viewed with the scanning tunneling
electron microscope (STEM).
Spectroscopy
• Nuclear Magnetic Resonance Imaging
– is a physical phenomenon based upon the quantum
mechanical magnetic properties of an atom's nucleus.
Magnetic Force Microscopy
• The tip the scans the
surface is magnetic.
• Used to sense the
local magnetic
structure on the
surface.
• Works in a similar
way to the reading
head on a hard disk
drive or audio
cassette player
• .
10x10 µm MFM images of magnetic tape, topography (A)
and phase image (B). The magnetic domains are ~ 650 nm
in length.
Electrochemistry
• Deals with how chemical processes can be changed by the
application of electric currents, and how electric currents can be
generated from chemical reactions.
• Nature of the surface atoms in an array can be measured directly
Electron Microscopy
•
•
Electrons are accelerated and passed through a sample. As the electrons
encounter nuclei and other electrons, they scatter. By collecting electrons
that are NOT scattered, we can construct an image that describes where
the particles were that scattered the electrons that didn’t make it through.
Based on the use of electrons rather than light to examine the structure and
behavior of the material.