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by mercuryrising 4683 days ago
I made this comment yesterday in another thread, but it provides some of 'why' for the colors we see in stained glass.

> You've seen it before... Stained glass. Stained glass was one of the first use of nanoparticles and plasmonics to become commonplace. The wide range of colors that you can get in stained glass is due to the nano properties of the materials you add to the glass. The effect is due to surface plasmons - electric field waves that travel on the surface of conductors. Much like ocean waves, plasmons are created from light's electric field. They bounce back and forth, and since they are only permitted on the surface of a material, there are limits on what waves can exist. This is what gives them the weird properties - the size and shape determine the optical properties.

On another tangent (this one's pretty cool) - since you can tune the properties of these nanoparticles, you can make them respond in a specific way. Let's say we have a cancer cell that we want to kill, and only that cancer cell should die. We can create nanoparticles that bond with that cancer cell, and only that cancer cell. But how do we kill it? We can tune the absorption spectrum of the nanoparticle to absorb infrared light - light that is transparent to the human body. We create a small heater that absorbs tons of the input energy, while keeping the rest of the area cool. Localized heating destroys the nearby cancer cell.

Plasmonics are really cool - http://en.wikipedia.org/wiki/Plasmon http://en.wikipedia.org/wiki/Plasmonic_Nanoparticles

2 comments

> light that is transparent to the human body.

That bit didn't make sense to me.

The rest does, I think what you're saying is that this is a tuned circuit which will absorb certain wavelengths.

Whoops, that should have been translucent. Yeah you tune the gold nanoparticles to absorb radiation that is able to be transmitted into the body (I can't find any graphs of the human body's vis/ir transmittance - although water is a good 'baseline'[1]). Tuning something to green wouldn't work so well, because you can't get the light in. But infrared works great - evidenced by how readily red light passes through fingers with flashlights.

[1] http://en.wikipedia.org/wiki/File:Absorption_spectrum_of_liq...

That still makes no sense: 1) light itself cannot be transparent or translucent, only objects, and 2) the human body is in fact opaque in the infrared, as evidenced by the fact that heat lamps warm us up.
I just watched this the other day: http://video.pbs.org/video/1754649512/
Couldn't see this video due to regional restrictions. Is this the same ? https://www.youtube.com/watch?v=XJRZ-OFKbuM
Yes, that is the same video.