Fluoresenssien

Fluoresenssien is the emission of light by a substance after it absorbs light or other electromagnetic radiation. The emitted light typically has a longer wavelength (lower energy) than the absorbed radiation, a phenomenon known as fluorescence. Fluorescence occurs on very short timescales, usually nanoseconds, and ceases almost immediately when the excitation source is removed. The process involves excitation of electrons to a higher singlet state, rapid relaxation to the lowest excited singlet state, and radiative decay back to the ground state with photon emission. A characteristic feature is the Stokes shift, the difference between excitation and emission wavelengths.

Fluorescent materials include organic dyes (for example, fluorescein, rhodamines), quantum dots, and certain minerals. The efficiency of fluorescence is described by the quantum yield, and the brightness depends on the product of the extinction coefficient and quantum yield. Fluorophores can be excited by ultraviolet or visible light, and emission is usually detected with specialized equipment such as fluorescence microscopes, spectrofluorometers, or cameras.

Applications are widespread in science and industry. In biology and medicine, fluorescent labels and probes enable tracking of cellular processes, gene expression, and diagnostic assays. In chemistry and materials science, fluorescence is used for sensing, imaging, and the study of molecular interactions. Photobleaching and autofluorescence can limit experiments, and spectral overlap between fluorophores requires careful choice of dyes and detection filters.

Fluoresenssien is a broad term that encompasses many fluorophores and applications, unified by the common mechanism of light emission triggered by light absorption.