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Are there materials that absorb light in the long wave radiation (like infrared Spectrum at room temperature) and emit light near the short wave radiation (say visible spectrum)?

Is there some source/list of objects (with their absorbed and emitted wavelength range mentioned) that behave as above?

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  • $\begingroup$ A light bulb and a diode emit visible light. They probably also absorb far infrared if cold enough. $\endgroup$ – my2cts Jun 23 '18 at 8:20
  • $\begingroup$ Thank you. I must clarify I was specifically looking for passive materials i.e. with no external energy source that work as asked and at room temperature (20-45 degree C). $\endgroup$ – TheoryQuest1 Jun 23 '18 at 8:23
  • $\begingroup$ Without an energy source no emission. There is no free lunch. $\endgroup$ – my2cts Jun 23 '18 at 9:37
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Short answer is that this does not happen naturally in a relevant amount.

Photons of shorter wavelength carry more energy. So a one-photon process will always have an emission spectra at the same or lower frequency than the excitation frequency (see common fluorophores here). As the opposite would violate energy conservation (with no external energy source, like you asked).

Nonetheless, there are two-photon processes that can yield shorter wavelength photons, but these tend to be very small effects, lets look at rubidium for example:

Rb Energy levels

You can see that it is possible to excite the atom to the 5D level with two IR photons to create a nice 420 nm photon. The problem is that the decay time of the intermediate level is very short (26 ns), so this will almost never happen unless you shoot lasers at it.

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  • $\begingroup$ Thank you. When I said no external source it simply meant other than the room air/temperature itself. I should have been more precise. Now what I had in mind was this: A material that could hypothetically absorb N photons (low energy from room environment) and emit a single photon (high energy). I think that would maintain the conservation of energy. But I am not aware of concrete examples/materials and their properties like this? $\endgroup$ – TheoryQuest1 Jun 23 '18 at 11:29

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