1. An Introduction to Nano-Science
& Nano-Technology
Dr. Abdul Waheed Anwar
Nanotechnology Research Center
Department of Physics
UET Lahore

2. What Is Nano?
• In 1959, a physicist named Richard Feynman shared his
vision that how very small things would look like and
how they would behave.
• In a speech at the California Institute of Technology titled
“There’s Plenty of Room at the Bottom,” Feynman gave
the first hint about what we now know as “nanoscience”
[1]
• “The principles of physics, as far as I can see, do not
speak against the possibility of maneuvering things atom
by atom.”
[1] http://www.zyvex.com/nanotech/feynman.html

3. What Is Nano?
Nanometer 10-9 meter 0.000000001 meter [1 nm]
One nanometer is one billionth of a meter, or the length of 10 hydrogen atoms lined up
So Nanoscience and Nanotechnolgy are the science and technology of things that are 10-9
to 10-7 meters in size [1-100 nm].
Comparisons & Scaling:
Biggest 1000 m = 103 m Height of tallest building
Everyday
Things 1 m = 100 m Height of people
0.001 m = 10-3 m size of a pinhead, smallest machined
parts (currently) [visible to naked eye]
0.000001 m = 10-6 m (electronic “micro” circuitry)
Small 10-7 m (bacteria)
10-8 m (viruses)
10-9 m
10-10 m diameters of atoms

4. Nano-Science & Nano-Technology
Is it science? Is it technology?
Nanoscience is the study of nano-materials, their properties
and related phenomena.
Nanotechnology is the application of nanoscience to produce
devices and products.

5. What is the Different About Nanoscience?
Just a bunch of really small things?
What makes the science at the nano scale special ?
 At such a small scale, all physical laws affect the behavior of matter.
 Different laws dominate over those that we experience in our everyday lives.
For example:
 Gold (Au) has a nice yellowish-brown color to it—the color we know as “gold.”
 However, if only 100 gold atoms are arranged in a cube, color would be much
more red.
 Color is just one property (optical) that is different at the nano scale.
Other properties, such a flexibility/strength (mechanical) and conductivity
(electrical) are often very different at the nano scale as well.

6. Very Large Surface Area
Size Volume Surface Area
Skyscraper (102 m)(102 m)(103 m) 2 (100 m 100 m) + 4 (100 m 1000 m)
= 107 m3 = 4.2 105 m2
Person (10-1 m)(10-1 m)(1 m) 2 (0.1 m 0.1 m) + 4 (0.1 m 1 m)
= 10-2 m3 = 0.42 m2
Small machine (10-3 m)(10-3 m)(10-3 m) 6 (0.001 m 0.001 m)
part = 10-9 m3 = 6.0 10-6 m2
Nano-cube 10-27 m3 6 (10-9 m 10-9 m)
= 6.0 10-18 m2

7. Very Large Surface to Volume Ratio
Look at the ratio of surface area (SA) to volume (V)
SA/V [m-1]
Skyscraper 4.2 10-2
Person 42
Small Machine part 6000
Nano-cube 6 109
Surface Area becomes relatively more important (compared to Volume) when
the things become smaller!

8. Bulk Sample
In terms of the number of atoms in objects (bulk and nano),
For example,
the number of atoms in a micro-cube (10-6 m on an edge)
3
10-6 m
= 1012 atoms
10-10 m
Enough atoms to behave like a “bulk” sample.
Bulk behavior = physical character of a macroscopic sample
(electrical, chemical, thermal, optical properties).

9. Nano Sample
Atoms in a nano-cube (10-9 m on an edge)
3
10-9 m
= 103 or 1000 atoms, with about 600 at the surface!
10-10 m
Not enough atoms to preserve bulk behavior.
Melting, heat conduction, electrical conductivity, chemical
reactivity, color, other optical properties,…all can change as we
move into the nano-world.
BUT does the science needed (chemistry, physics, biology)
change as we approach the nano-world?

10. Nano World
Quantum World Nano World Micro World Everyday World
Atoms Molecules Classical Physics
& Chemistry
0.1 nm 0.2 – 100 nm 103 nm 103 – 109 nm
The Nano World—its science and technology—is at the boundary between
the everyday world of classical science and the unusual world of Quantum
Mechanics.
Some Nano aspects can be handled with everyday physics & chemistry, and
some nano devices can only be understood with quantum concepts.

11. Small Devices
1965, Gordon E. Moore (co-founder of Intel) : number of transistors
squeezed onto a computer chip roughly doubles every 18 months.
This is known as “Moore’s Law.”
The more transistors on a chip, the smaller their size and
closer their spacing .
This is why computers of room size in the 1950s now fit on your lap.

12. Nanostructures
Two interesting structures that have been constructed and fall into the
nanoscale range are carbon nanotubes and buckyballs.
in Nature

13. How to “See” Nano Structures
STM: Scanning Tunneling Microscope which was developed in 1981.
The very end of the tip of this microscope is one atom in size.
 The “tunneling” of electrons (quantum tunneling) between the tip and the
substance being viewed creates a current (flow of electrons).
The strength of the current and how it changes over time can
be used to create an image of the surface of the substance.
Today’s scanning microscopes can do much more than just see.
Among other things, they can be used to move atoms around and arrange them
in a preferred order.

14. How to “See” Nano Structures
STM tip
Surface
atoms
Battery powered
circuit

15. How to “See” Nano Structures
A different type of microscope, the atomic force microscope
(AFM), uses a tiny tip that moves in response to the
electromagnetic forces between the atoms of the surface and
the tip.
As the tip moves up and down, the motion is recorded and an
electronic image of the atomic surface is formed

16. How to “See” Nano Structures
As the AFM tip is attracted to the surface (causing the cantilever to
bend), a laser beam bounces off the end of the cantilever—allowing the
tip’s movement to be tracked.
Laser
~1 m (1000 nm)
The cantilever is visible to the naked eye but
the AFM tip is too small to see without
magnification.

17. How to “See” Nano Structures
AFM tip
Surface of
sample
The attractive van der Waals interaction acts at a molecular and atomic
level, between the AFM tip and the local atoms at the sample’s surface.