Scintillator
A scintillator is a device or substance that absorbs an electromagnetic wave of one wavelength and emits an electromagnetic wave of a different wavelength.
Common-life examples include
- the milky-white internal coating in neon lighting tubes, which converts the ultraviolet light emitted by the neon plasma to visible light
- the yellowish white coating on the chip in a "white" light emitting diode (LED). This converts part of the visible blue light emitted by the LED chip to visible yellow light. The blue and yellow light together create the subjective impression of white light.
In principle, Scintillators can have any aggregate state: gaseous, liquid or solid state. Most scintillators for practical use will come in solid state form.