Luminescence, Fluorescence & Phosphorescence

Luminescence is the emission of light from a substance not resulting from heat; it can be caused by chemical, electrical, or physiological means. Fluorescence is a type of luminescence where a substance absorbs light at one wavelength and emits it at a longer wavelength almost instantaneously. Phosphorescence, on the other hand, is a type of luminescence where a substance absorbs light and then re-emits it slowly over a period of time, even after the original light source is removed.

Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. The emitted light has a longer wavelength than the absorbed radiation, and the process typically occurs very quickly, often within a fraction of a second after the absorption of the excitation energy. This phenomenon is commonly observed in certain substances, such as fluorescent dyes, that are used in various applications, including microscopy, medical diagnostics, and environmental monitoring

Phosphorescence is a type of photoluminescence in which a substance absorbs photons (electromagnetic radiation) and then re-emits them slowly over a longer time scale than in fluorescence. This delayed emission of light can continue for milliseconds to hours, or even longer, after the excitation source is removed. Phosphorescent materials are used in various applications, including glow-in-the-dark products, some types of safety signs, and certain types of lighting.