Fluorescerande

Fluorescerande describes a property where a substance emits light after being excited by another energy source, usually by absorbing higher-energy photons and releasing photons with longer wavelengths. This phenomenon is a form of luminescence called fluorescence. The term traces its origin to observations of glowing minerals such as fluorite under ultraviolet light.

In a fluorescent material, photons promote electrons from a ground state to a higher-energy singlet state. The excited electrons quickly return to the ground state, emitting light in the visible range or other parts of the spectrum. The emission stops when the excitation source is removed, occurring on a very fast timescale (nanoseconds). The difference between the excitation and emission wavelengths is known as the Stokes shift. The efficiency of fluorescence is described by the quantum yield, which varies between substances and depends on factors like environment and concentration.

Fluorescerande materials encompass a wide range of substances. Organic dyes such as fluorescein and rhodamine, fluorescent proteins like GFP and its derivatives, and inorganic options like quantum dots or rare-earth–doped crystals are common examples. Fluorescence is also exploited in coatings and pigments that glow under ultraviolet light, as well as in fluorescent phosphors used in lighting and display technologies.

Applications span science, medicine, industry and safety. In biology and medicine, fluorescence enables microscopy, flow cytometry, DNA probes and diagnostic assays. In industry, fluorescent materials are used for security features, anti-counterfeiting, sensors and imaging technologies. Limitations include photobleaching (loss of signal with light exposure) and potential toxicity or environmental concerns for certain dyes.