Nano Questions

Day 1 Scale

What is the density of cosmic dust?

According to George Mason University Astronomy:

There are on the average of 1000 dust particles in each cubic kilometer.

or 10^-12 particles per m^3

What is a model of a photon?

Electrostatics: Charge styrofoam...electrophorus  rub styrofoam with wool.

Explore Electric charge with Scotch magic Tape

The sign of the mobile charge carrier was first measured by Tolman and Stewart.

They used a galvanometer to measure the charge distribution in an accelerated metal.

If a copper metal block was acelerated upward the bottom became negative relative to the top. Because the negative electrons had inertia and were mobile.

So as the atomic cores of the copper atoms acclerated upward the conduction electrons were free to  lag behind and accumulate at the bottom.

Powers of 10 the video is available on VIMEO

The length of a photon

The transition from a 2p to a 1s orbital can take 10^-8 s. Durring one transition the electron is in a superposition of the 1s and 2p orbitals, it oscillates back and forth between these orbitals at the frequency of the emitted light. 6 x 10^14 Hz for the transition time of 10^-8 s. The length of the photon is 3 x 10^8 m/s x 10^-8s = 3 m.

In this 3 m of length there are 6 x 10^14 s^-1 * 10^-8 s =  6 x 10^6 oscillations of green light.

The width of the probability density wave parcel is gaussian in profile and mostly contained within a diameter of 1 wavelenth 550 nm.

The diameter of an atom

Feynman quote

Physicist Richard Feynman once said that if he knew that all scientific information was going to be lost, but that he could pass on one sentence to the future it would be a summary of the atomic theory: All the world is made of atoms, small indivisible particles that repel each other when close together and attract each other when a little ways apart.

From the physics Factbook:

"The diameter of an atom ranges from about 0.1 to 0.5 nanometer"

P.W. Atkins Physical Chemistry P409 "One finds that all atoms are roughly the same size with d = 0.3 +- 0.1 nm." Note in this quote he says r but he means to say d for diameter.

But actually atomic radius is a bit more complicated than this.

From hyperphysics we have this plot of atomic radius

atomic radius



Day 2 Tools

Big Ideas in Nanoscale Science, NSTA  The 9 fundamental science concepts for nanotechnlogy.


Magnet Viewing paper  From Educational Innovations

Earth globe with a magnet inside  3D compass (Magnaprobe)  from Arbor Scientific

scanning light microscope

Sodium Alginate, To buy sodium alginate

MSDS for Phenolphthalein

MSDS sand

Rydberg atoms


3 Self Assembly

Troy's links to liquid crystal labs

Airplane center of gravity, center of pressure.

Deletum anti grafiti paint

“Deletum 5000’s special ingredient is silica. It is loaded with particles of the stuff that are but a few nanometres (billionths of a metre) across. These particles have had both oil-repellent and water-repellent molecules attached to their surfaces. Both are necessary, since the materials used by graffiti artists may be oil-based or water based. However, if merely mixed together, the two would end up repelling each other, and thus separating. By attaching them to the silica, this mutual loathing can be overcome and, as the paint dries, the changes that take place force the oil-and-water-proofing to the surface. The result is that most agents used by graffiti artists will not stick to that surface—and what does stick can be washed or brushed off easily.”

Powdered donut solar cell

Wisconsin MRSC homepage

Wisconsin MRSC nano explorations

Silver as an antimicrobial

Antimicrobial silver  Discovered in 1893 by the Swiss KW Nägeli as a toxic effect of metal-ions on living cells, algae, moulds, spores, fungi, virus, prokaryotic and eukaryotic microorganisms, even in relatively low concentrations. This antimicrobial effect is shown by ions of: mercury, silver, copper, iron, lead, zinc, bismuth, gold, aluminum and other metals.
Especially heavy metals show this effect. The exact mechanism of action is still unknown. Data from silver suggest that these ions denature proteins (enzymes) of the target cell or organism by binding to reactive groups resulting in their precipitation and inactivation. Silver inactivates enzymes by reacting with the sulfhydryl groups to form silver sulfides. Silver also reacts with the amino-, carboxyl-, phosphate-, and imidazole-groups and diminish the activities of lactate dehydrogenase and glutathione peroxidase. Bacteria (gram+ and gram-) are in general affected by the oligodynamic effect, but they can develop a heavy-metal resistance, or in the case of silver a silver-resistance. Virus in general are not very sensitive. The toxic effect is fully developed often only after a long time (many hours).


Blue skin as a result of ingesting silver.  silver blue skin

0.1 milligram of water/ 18 g/mole = 5 x 10^-6 moles    x 6* 10^23 =  30 * 10^17 = 3000000000000000000.  molecules of water

Butterfly irridescence

says Sir Isaac Newton in his book Opticks, published in1704, put forward a reason for the iridescent nature of the colour from the feathers of peacock tails.

Digital microscope  Celestron $50  10x to 150x  USB

Sea mouse irridescent hairs sea mouse spines

Opal  opal beads of amorphous silica


Layers of silica balls in opal create irridescence.

Blue morpho buttefly


The wings of M. rhetenor [17] are tiled with a single layer of blue scales.
These scales are typically 75μm by 200μm in size. On the upper surface they
have a longitudinal ridging with an in-plane periodicity of (675
± 75)nm. The
ridges have a pine-tree cross-sectional shape as shown in figure 1.2, with ten
branches attached on both sides to a central stem, horizontal and regularly
ordered, with a vertical thickness of about 90nm. The thickness of the air
interstices is also about 90nm, which results in an average periodicity of
180nm. The trees are wide with respect to the in-plane periodicity and the
cuticle material (chitin) fills approximately 30% of the volume occupied by
the structure.

The index of refraction of Chitin is 1.56

c = L f   c = speed of light, f = frequency, L = wavelength

The frequency of the light remains  constant so c/L is a constant

In chitin the speed of light is reduced to 2/3 of the speed in a vacuum. c = cvacuum /n

The wavelength of blue light in a vacuum is 450 nm, in pure chitin it is Lvacuum /c vacuum = Lchitin /c chitin  and so L chitin= L vacuum * L Cchitin/c vacuum

L chitin = 450 nm 2/3 = 300 nm

now the wave travels through 50% chitin 50% air so the wavelength averages to 375 nm.  and half a wavelength is 190 nm  very close to the 180 nm spacing between the tops of the tree limb pattern.

Great book "The Gecko's Foot"

polystyrene spheres how to make them.

Polysciences makes polystyrene spheres.

Peacock Color A scientific article.

Superhydrophobic plants

Beetle colors from Rashmi

Liquid Crystal Labs

Day 4 LEDs

Solid State physics on hyperphysics

The nanoventure game


Day 5 Stanford

Center for Probing the Nanoscale

CPN nano-activities

CPN powerpoint images

NSTA Nanoscale Science, book for teaching nanoscale science.

You have a nanoprobe in your computer.

The width of a domain in a modern hard drive is 50 nm

Piezo electric motion

The wavelentgth of an electron in a color TV is 0.012 nm

Paper battery




Scientific Explorations with Paul Doherty

© 2010

7 April 2010