Download STM/AFM Images - Purdue College of Science

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Explanations from
Scanning Tunneling Microscopy
In 1981, the Scanning Tunneling microscope
was developed by Gerd Binnig and Heinrich
Rohrer – IBM Zurich Research Laboratories in
Switzerland (Nobel prize in physics in 1986).
This instrument works by scanning a very sharp
metal wire tip over a sample very close to the
surface. By applying an electric current to the tip
or sample, we can image the surface at an
extremely small scale – down to resolving
individual atoms.
Quantum mechanics tells us that
electrons have both wave and
particle like properties.
Tunneling is an effect of the
wavelike nature. The top image
shows us that when an electron
(the wave) hits a barrier, the
wave doesn't abruptly end, but
tapers off very quickly. For a
thick barrier, the wave doesn't
get past.
The bottom image shows the
scenario if the barrier is quite
thin (about a nanometer). Part of
the wave does get through, and
therefore some electrons may
appear on the other side of the
The number of electrons that will actually tunnel is
very dependent upon the thickness of the barrier.
The actual current through the barrier drops off
exponentially with the barrier thickness.
To extend this description to the STM: The barrier
is the gap (air, vacuum, liquid) between the
sample and the tip. By monitoring the current
through the gap, we have very good control of the
tip-sample distance.
Computer software is used to add color
and analyze the captured data.
Use images from Science Express laptop.
Diffraction Grating
3-D View: Diffraction Grating
Diffraction Grating - Analysis
Red Blood Cells
Red Blood Cells – Analysis
3-D View : Graphite
Graphite - Analysis
Graphite - magnified
Graphite - magnified
Graphite - magnified
Graphite – magnified – AGAIN!
Graphite – magnified – AGAIN!
Graphite – magnified – AGAIN!
Purdue University
Physics Department
Atomically flat
gold film.
Atoms of Highly
Oriented Pyrolytic
Graphite (HOPG).
Atomic Force Microscopy
In principle, the AFM works like the
stylus on an old record player.
There is actual contact between the
probe tip and the sample.
The following explanation taken from
Atomic Force Microscopy
1. Laser
2. Mirror
3. Photodetector
4. Amplifier
5. Register
6. Sample
7. Probe
8. Cantilever
Atomic Force Microscopy
DIC (Differential Interference
DIC (Differential Interference Contrast) image
of human lymphocyte
lymphocyte metaphase
metaphase chromosomes on microscopy
chromosomes on microscopy
dimensions 83 µm * 83 µm
dimensions 83 µm * 83 µm
height image (left, 3D plot) and
corresponding optical
microscope image (above, bright
field) of a
moth wing scale
height image (left, 3Dintermittent
field 10 µm * 10 µm
corresponding optical scan
z-range 0 - 1.7 µm
image (above, bright field) of a
moth wing scale
intermittent contact mode
scan field 10 µm * 10 µm
z-range 0 - 1.7 µm
Height image (left, 3D plot) and corresponding
optical microscope image (above, phase
of a moth's eye - region of three adjacent
intermittent contact mode
scan field 10 µm * 10 µm
z-range 0 - 6.0 µm
Atomic force microscope topographical scan of a glass surface. The micro and nano-scale features of
the glass can be observed, portraying the roughness of the material.
Constructed at the Nanorobotics Laboratory at Carnegie Mellon University (
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