Physics
Negative luminescence is most readily observed in semiconductors. Incoming infrared radiation is absorbed in the material by the creation of an electron–hole pair. An electric field is used to remove the electrons and holes from the region before they have a chance to recombine and re-emit thermal radiation. This effect occurs most efficiently in regions of low charge carrier density.
Negative luminescence has also been observed in semiconductors in orthogonal electric and magnetic fields. In this case, the junction of a diode is not necessary and the effect can be observed in bulk material. A term that has been applied to this type of negative luminescence is galvanomagnetic luminescence.
Negative luminescence might appear to be a violation of Kirchhoff's law of thermal radiation. This is not true, as the law only applies in thermal equilibrium.
Another term that has been used to describe negative luminescent devices is "Emissivity switch", as an electric current changes the effective emissivity.
Read more about this topic: Negative Luminescence
Famous quotes containing the word physics:
“... it is as true in morals as in physics that all force is imperishable; therefore the consequences of a human action never cease.”
—Tennessee Claflin (1846–1923)
“He who is conversant with the supernal powers will not worship these inferior deities of the wind, waves, tide, and sunshine. But we would not disparage the importance of such calculations as we have described. They are truths in physics because they are true in ethics.”
—Henry David Thoreau (1817–1862)
“The labor we delight in physics pain.”
—William Shakespeare (1564–1616)