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Author Topic: Can any opaque solid become transparent?  (Read 874 times)

Offline memoryerase1

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Can any opaque solid become transparent?
« on: 07/01/2016 22:17:12 »
Can any opaque solid become transparent so long as the "right" kind of light, which won't excite the material's electrons, is used?

Or does the material need to be a amorphous solid, like glass, water, and gas.
If hydrogen does not get exited by green yellow light then some other atoms electrons in other elements should not get exited right.

Or is this just because its a gas, and not a solid.

Could carbon, which is a solid become transparent.

Thank you for your help, anything helps even a few words.
« Last Edit: 08/01/2016 08:00:51 by chris »


 

Offline chiralSPO

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There are many examples of transparent crystalline materials:
diamond, quartz, sodium chloride, calcium carbonate etc.

As far as visible light is concerned, electronic transitions and plasmon resonances are most likely reasons for a material to be colored, transparent or opaque.
 

Offline evan_au

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Can any opaque solid material become transparent, as long as you shine the right kind of light at the materials (so the) electrons don't get excited?
I think it's unlikely to be achieved for a material that is opaque at every frequency.

But for some materials that absorb a certain frequency strongly, it is possible to "pump" the electrons into a higher energy state. If this state is "metastable" (ie it takes a relatively long time for the electrons to fall back to the low energy state), then there will be a "population inversion", with few electrons in the ground state, and it will become fairly transparent to the pump frequency (where it was previously opaque).

This effect is used in lasers.

If you stop the pump frequency, it will again be opaque to the pump frequency.
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(1) If hydrogen does not get exited by green yellow light then (2) some other atoms electrons in other elements should not get excited, right?
I would say that (1) and (2) are independent.
(1) Hydrogen has a particular set of energy levels, due to its 1 proton charge n the nucleus, and 1 electron. At room temperature, Hydrogen is transparent to green and yellow light (ie the single electron does not get excited by these frequencies).
(2) Other elements have quite different energy levels, due to their multiple protons, and multiple electrons. I am sure that many elements will have electrons excited by green and yellow light at room temperature. If you include compounds of several elements, the combinations are enormous!

So I have trouble linking the two parts of this question. This sounds like a "non sequitur".

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Could carbon, which is a solid become transparent?
Yes, you just need to crush it to pressures and temperatures found about 150km beneath Earth's surface, where it changes crystal structure to diamond, which is transparent at room temperature.

Or you could view it with X-Rays, where graphite is fairly transparent (and diamonds fluoresce).
 

Offline alysdexia

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Re: Can any opaque solid become transparent?
« Reply #3 on: 09/01/2016 17:54:37 »
The conduction band of metals fails at EUV: en.wikipedia.org/wiki/Plasmon.  And their complex refraction defines their finite extinction coefficient so that you can get a clear micron film: en.wikipedia.org/wiki/Refractive_index#Complex_refractive_index.

There are two ways to get transparent [solid] aluminium, both by diffraction, antireflective layers and metamaterial lattices: en.wikipedia.org/wiki/Anti-reflective_coating, en.wikipedia.org/wiki/Extraordinary_optical_transmission.
 

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Re: Can any opaque solid become transparent?
« Reply #3 on: 09/01/2016 17:54:37 »

 

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