fluoreszcenciát

Fluoreszcencia is a photophysical phenomenon where a substance absorbs light at a specific wavelength and then re-emits light at a longer wavelength. This emission is nearly instantaneous, occurring within nanoseconds of absorption. The absorbed energy excites electrons in the molecule to a higher energy state. As these electrons return to their ground state, they release the excess energy as photons of light. The color of the emitted light depends on the specific substance and its molecular structure. Different fluorescent materials absorb and emit light at distinct wavelengths, making them useful for various applications.

This property is exploited in numerous fields. In biology and medicine, fluorescent dyes are used as markers to visualize cells, tissues, and molecules, aiding in diagnostics and research. For example, fluorescent proteins like GFP (Green Fluorescent Protein) are vital tools in molecular biology. In analytical chemistry, fluorescence spectroscopy allows for the detection and quantification of trace amounts of substances. Beyond scientific applications, fluorescence is used in security features on currency and identification documents, in fluorescent lighting, and in optical brighteners found in detergents and paper. The efficiency of fluorescence, measured by quantum yield, indicates the proportion of absorbed photons that are re-emitted. Not all substances that absorb light fluoresce; some lose energy through non-radiative processes like heat.