# Nanotechnology/Physics#Quantized Nano Systems

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 Quantum mechanics and classical
mechanics are still valid on the nanoscale - but many assumptions we are
used to take for granted are no longer valid. This makes many
traditional systems difficult to make on the atomic scale -if for
instance you scale down a car the new relation between adhesion forces
and gravity or changes in heat conduction will very likely make it
perform very poorly if at all - but at the same time a wealth of other
new possibilities open up!

 Scaling laws can be used to determine how
the physical properties vary as the dimensions are changed. At some
point the scaling law no longer can be applied because the assumptions
behind it become invalid at some large or small scale.

So, scaling is one thing - the end of scaling another, and surfaces a
third! For instance at some point the idealized classical point of view
on a system being downscaled will need quantum mechanics to describe
what\'s going on in a proper way, but as the scale is decreased the
system might also be very different because the interaction at the
surface becomes very significant compared to the bulk.

This part will try to give an overview of these effects.

# Scaling laws

 Scaling laws can be used to describe how
the physical properties of a system change as the dimensions are
changed.

! The scaling properties of physical laws is an important effect to
consider when miniaturizing devices. On the nanoscale the mass and heat
capacity become very unimportant, whereas eg. surface forces scaling
with area become dominant.
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# Quantized Nano Systems

 Quantum wires are examples of nanosystems
where the quantum effects become very important.

 Break junctions is another example.

Resources

-   Simple model of conduction -
    the classical case

# Bulk matter and the end of bulk: surfaces

-    Surface states are electronic states
    on the surface of a material, which can have radically different
    properties than the underlying bulk material. For instance, a
    semiconductor can have superconducting surface states.

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-   Surface reconstruction

The surface of a material can be very different from the bulk because
the surface atoms rearrange themselves to lower their energy rather than
stay in the bulk lattice and have dangling bonds extending into space
where there is no more material. Atoms from the surroundings will easily
bind to such surfaces and for example for silicon, more than 2000
surface reconstructions have been found, depending on what additional
atoms and conditions are present.

-   Surface plasmons

 Plasmons are collective oscillations of the
electrons in matter, and the electrons on the surfaces can also make
local plasmons that propagate on the surface.

# The Tyndall Effect

The Tyndall Effect is caused by reflection of light off of small
particles such as dust or mist. This is also seen off of dust when
sunlight comes through windows and clouds or when headlight beams go
through fog. The Tyndall Effect can only be seen through colloidal
suspensions. A colloid is a substance that consists of particles
dispersed throughout another substance, which are too small for
resolution with an ordinary light microscope but are incapable of
passing through a semi permeable membrane. The Tyndall Effect is most
easily visible through liquid using a laser pointer. The Tyndall Effect
is named after its discoverer, the 19th-century British physicist John
Tyndall.[^1][^2][^3][^4][^5][^6]

# References

See also notes on editing this book about how to add references
Nanotechnology/About#How_to_contribute.

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[^1]: "Tyndall Effect." Silver Lighting. 1 June 2008.
    <http://silver-lightning.com/tyndall/>

[^2]: Davies, Paul. The Tyndall Effect. 1 June 2008.
    <http://www.chm.bris.ac.uk/webprojects2002/pdavies/Tyndall.html>

[^3]: SonneNebel. 1 July 2008.
    <http://upload.wikimedia.org/wikipedia/commons/f/f6/SonneNebel.jpg>

[^4]: Bright Flashlight. 1 July 2008.
    <http://www.geekologie.com/2008/02/04/bright-flashlight.jpg>

[^5]: "The Tyndall Effect."

    `http://www.chm.bris.ac.uk/webprojects2002/pdavies/Tyndall.html`` `

[^6]: "Colloid." 3 June 2008.
    <http://www.merriam-webster.com/dictionary/colloid>
