I'm not sure I get how the beads re-radiate energy at 8 microns that came in at other frequencies. If the energy didn't come in at a different frequency, then the building isn't going to end up any cooler. If it did, then the beads are essentially phosphorescing in the IR region, aren't they? Or exhibiting some other form of nonlinear conversion?
I would believe that the heat energy gets transferred to the beads by conduction and or radiation.
I tend to think this is like a gas mantle in a gasoline (propane) lantern. The mantle is doped with rare earth that emit more strongly in the visible section than a black body would. On this case the temperature is much lower of course and the glass beads are sized to emit strongly in an the infrared band that isn't absorbed by the atmosphere.
So, couple this, in terms of the dispersion of energy:
"Our hybrid metamaterial is extremely emissive across the entire atmospheric transmission window (8-13 μm) due to phonon-enhanced Fröhlich resonances of the microspheres."
And this in terms of the absorbtion:
"In the case of large microspheres, modal interference between higher order modes makes the hybrid metamaterial strongly infrared-absorbing."
And finally this in terms of reflectance:
"The hybrid metamaterial strongly reflects solar irradiation when backed with a 200-nm-thick silver thin film prepared by electron beam evaporation... The measured spectral absorptivity (emissivity) of the sample (Fig. 3D) indicates that the 50-μm-thick film reflects ~ 96% solar irradiation..."
I don't know about this particular technology but as a parallel all Florescent Lights operate on a similar concept. They absorb radiation at frequency X and emit in frequency Y where Y is visible light.
It appears that the researchers have tuned the emission to a frequency that is not reabsorbed by the atmosphere but emitted unimpeded into space. Pretty clever engineering.
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I'm not sure I get how the beads re-radiate energy at 8 microns that came in at other frequencies. If the energy didn't come in at a different frequency, then the building isn't going to end up any cooler. If it did, then the beads are essentially phosphorescing in the IR region, aren't they? Or exhibiting some other form of nonlinear conversion?
That would be pretty cool, no pun intended.
I would believe that the heat energy gets transferred to the beads by conduction and or radiation.
I tend to think this is like a gas mantle in a gasoline (propane) lantern. The mantle is doped with rare earth that emit more strongly in the visible section than a black body would. On this case the temperature is much lower of course and the glass beads are sized to emit strongly in an the infrared band that isn't absorbed by the atmosphere.
I'm not entirely sure about the mechanism, but it appears to work via phonon-polariton resonance:
https://en.wikipedia.org/wiki/Polariton
So, couple this, in terms of the dispersion of energy: "Our hybrid metamaterial is extremely emissive across the entire atmospheric transmission window (8-13 μm) due to phonon-enhanced Fröhlich resonances of the microspheres."
And this in terms of the absorbtion: "In the case of large microspheres, modal interference between higher order modes makes the hybrid metamaterial strongly infrared-absorbing."
And finally this in terms of reflectance: "The hybrid metamaterial strongly reflects solar irradiation when backed with a 200-nm-thick silver thin film prepared by electron beam evaporation... The measured spectral absorptivity (emissivity) of the sample (Fig. 3D) indicates that the 50-μm-thick film reflects ~ 96% solar irradiation..."
I don't know about this particular technology but as a parallel all Florescent Lights operate on a similar concept. They absorb radiation at frequency X and emit in frequency Y where Y is visible light.
It appears that the researchers have tuned the emission to a frequency that is not reabsorbed by the atmosphere but emitted unimpeded into space. Pretty clever engineering.