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There are any number of fluorescent materials that glow when exposed to UV light.

But what if I wanted such a material that only glows in response to very specific wavelengths, emitting no visible light at all in response to any others? Is such a material possible to create, and how would it work?

EDIT: The original phrasing of this question could have been interpreted as asking about materials that only emit certain wavelengths instead of materials that only emit in response to certain wavelenghts. Edited to make it clear that the second meaning was the intended one.

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  • $\begingroup$ how about quantum dots? $\endgroup$ – wcc Jul 2 at 0:45
  • $\begingroup$ @wcc Sounds promising, could you expand that into an answer? $\endgroup$ – Tal Jul 2 at 1:03
  • $\begingroup$ Sorry, but I have no detailed knowledge of the products. A cursory search tells me that UV quantum dots (wavelength <400 nm) are not available (although it seems there are experimental demonstrations). You can buy suspended quantum dots that emit blue, for sure. $\endgroup$ – wcc Jul 2 at 1:20
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Fluorescence works with vibrational relaxation. The molecule first goes to vibrational sublevels, which are over the first excited state (LUMO). Then with vibrational relaxation, it goes to LUMO.

Then, comes the fluorescence itself, that is a deexitation via emission of a photon. This way the molecule goes back to ground state (HOMO).

Now the emitted photons this way always have a longer wavelength (smaller energy), then the absorbed ones.

When a molecule absorbs a photon of UV or visible light, an electron moves from the HOMO to the LUMO to create either the excited state in its ground vibrational level, or the excited state vibrationally excited. From the sublevels, it can undergo “vibrational relaxation”, which causes it to lose a little bit of energy non-radiatively (that is, without emitting a photon), and drop back down to the ground state. Once it reaches the lowest vibration level of the excited state, it can emit a photon and drop back to the ground state or the ground state vibrationally excited, or it can decay back to ground state non-radiatively by emission of heat.

http://www.orgchemboulder.com/Labs/Handbook/UV-Vis.pdf

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You are asking whether certain materials will fluoresce only in response to certain wavelengths.

http://www.starna.com.au/docs/FMaterials.PDF

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It is possible to do Molecular fluorescence spectrophotometry, and create certain materials that will only emit (fluoresce) if a certain wavelength photon excites their molecules.

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  • $\begingroup$ Any chance you have a few terms I can search for to find more information on such materials? $\endgroup$ – Tal Jul 4 at 21:24

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