Definitions: F

Förster resonance energy transfer (FRET) is a mechanism describing the transfer of energy between two closely spaced fluorescent molecules. This phenomenon is named after the German scientist...

The decrease of a component's efficiency, or a reduction in a material's light sensitivity, as the result of accumulated exposures to radiant energy.

A femtosecond laser is a type of laser that emits ultrashort pulses of light with durations on the order of femtoseconds, where one femtosecond is equal to 10-15 seconds. These lasers are capable of...

The mathematical expression of the probability of any given state of energy being occupied when a semiconductor is in thermal equilibrium.

A bundle of optical fibers arranged randomly for the purpose of transmitting energy, not an image.

In solar energy technology, the percent of usable land covered by collectors. The horizontal collector is the only design that exhibits 100 percent fill factor.

The study and interpretation of the spectra of substances after they have absorbed the radiant energy emitted by a brief, intense light source.

A device that converts stored electrical energy into light by means of a sudden electrical discharge.

Flow chemistry, also known as continuous-flow chemistry, is a chemical manufacturing process where reactions take place in a continuous stream of fluids (liquids or gases) rather than in batch...

A flowmeter is a device used to measure the flow rate or quantity of a fluid passing through a particular point in a system. It works by sensing the velocity of the fluid passing through it and...

Fluence is a term used in various scientific and technical disciplines to describe the amount of something per unit area. The specific meaning of fluence can vary depending on the context in which it...

A device, also called a fluorescence lifetime instrument, that measures decay curves of fluorescing samples. It generally consists of a gated pulsed flashlamp or a cavity dumped dye laser...

A fluorescent screen refers to a phosphorescent or fluorescent-coated surface that emits visible light when exposed to other forms of electromagnetic radiation, such as x-rays or ultraviolet light....

A fluorophore is a molecule or a portion of a molecule that has the ability to emit light upon excitation by an external energy source, such as ultraviolet or visible light. The process by which a...

A special laser glass made primarily of fluoride compounds that exhibits extremely low refractive index and allows greater levels of energy to be generated as the laser beam passes through the...

Time rate of flow of energy; the radiant or luminous power in a beam.

A solid-state laser consisting of active atoms or ions of a transition metal, rare-earth metal or actinide, imbedded in a crystal or glass material, often garnet. Excitation and transfer to different...

The principle that electronic energy transitions occur at such speeds that the nuclei of the atoms in the molecular system remain stable during the transfers.

The phenomenon whereby an electron within a band absorbs radiation by transferring from a low-energy level to an empty high-energy level.

A free-electron laser (FEL) is a type of laser that generates coherent, high-intensity electromagnetic radiation by using a beam of accelerated electrons as the lasing medium. Unlike traditional...

A Fresnel lens is a type of optical lens that consists of a series of concentric grooves or steps carved into a flat, thin piece of transparent material, typically plastic or glass. This design...

Functional materials refer to materials that possess specific properties or functionalities that make them suitable for particular applications or purposes. These materials are designed and...

Fusion ignition refers to the point in a controlled nuclear fusion reaction where the energy released by the fusion reactions becomes self-sustaining, leading to a continuous release of energy...