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  2. Photon upconversion - Wikipedia

    en.wikipedia.org/wiki/Photon_upconversion

    Optical fiber that contains infrared light shines with a blue color in the dark. Photon upconversion (UC) is a process in which the sequential absorption of two or more photons leads to the emission of light at shorter wavelength than the excitation wavelength. It is an anti-Stokes type emission. An example is the conversion of infrared light ...

  3. Electromagnetic spectrum - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_spectrum

    The electromagnetic waves in each of these bands have different characteristics, such as how they are produced, how they interact with matter, and their practical applications. Radio waves, at the low-frequency end of the spectrum, have the lowest photon energy and the longest wavelengths—thousands of kilometers, or more.

  4. Photosynthetically active radiation - Wikipedia

    en.wikipedia.org/wiki/Photosynthetically_active...

    Blue light, while not delivering as many photons per joule, encourages leaf growth and affects other outcomes. [9] [11] The conversion between energy-based PAR and photon-based PAR depends on the spectrum of the light source (see Photosynthetic efficiency). The following table shows the conversion factors from watts for black-body spectra that ...

  5. Visible spectrum - Wikipedia

    en.wikipedia.org/wiki/Visible_spectrum

    An example of this phenomenon is when clean air scatters blue light more than red light, and so the midday sky appears blue (apart from the area around the Sun which appears white because the light is not scattered as much). The optical window is also referred to as the "visible window" because it overlaps the human visible response spectrum.

  6. What's up with the mysterious purple streetlights at the ...

    www.aol.com/news/whats-mysterious-purple...

    The science behind the white to purple light change. ... LED lights are made of a blue LED light combined with the yellow phosphor that produces white light. In the Acuity lights, the phosphor ...

  7. Absorption (electromagnetic radiation) - Wikipedia

    en.wikipedia.org/wiki/Absorption_(electromagnetic...

    A white light source—emitting light of multiple wavelengths—is focused on a sample (the pairs of complementary colors are indicated by the yellow dotted lines). Upon striking the sample, photons that match the energy gap of the molecules present (green light in this example) are absorbed, exciting the molecules. Other photons are scattered ...

  8. Electromagnetic radiation - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_radiation

    Classically, electromagnetic radiation consists of electromagnetic waves, which are synchronized oscillations of electric and magnetic fields. In a vacuum, electromagnetic waves travel at the speed of light, commonly denoted c. There, depending on the frequency of oscillation, different wavelengths of electromagnetic spectrum are produced.

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