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Phosphorescence is a type of photoluminescence related to fluorescence. When exposed to light (radiation) of a shorter wavelength, a phosphorescent substance will glow, absorbing the light and reemitting it at a longer wavelength. Unlike fluorescence, a phosphorescent material does not immediately reemit the radiation it absorbs.
Jablonski diagram including vibrational levels for absorbance, non-radiative decay, and fluorescence. When a molecule absorbs a photon, the photon energy is converted and increases the molecule's internal energy level. Likewise, when an excited molecule releases energy, it can do so in the form of a photon.
Jablonski diagram shows the energy levels in a fluorescing atom in a phosphor. An electron in the phosphor absorbs a high-energy photon from the applied radiation, exciting it to a higher energy level. After losing some energy in non-radiative transitions, it eventually transitions back to its ground state energy level by fluorescence, emitting ...
Phosphorescence is similar to fluorescence in its requirement of light wavelengths as a provider of excitation energy. The difference here lies in the relative stability of the energized electron. The difference here lies in the relative stability of the energized electron.
Electrons change energy states by either resonantly gaining energy from absorption of a photon or losing energy by emitting photons. In chemistry-related disciplines, one often distinguishes between fluorescence and phosphorescence. The former is typically a fast process, yet some amount of the original energy is dissipated so that re-emitted ...
Phosphorescence is a property of materials to absorb light and emit the energy several milliseconds or more later (due to forbidden transitions to the ground state of a triplet state, while fluorescence occurs in excited singlet states). Until recently, this was not applicable to life science research due to the size of the inorganic particles.
A corollary of Kasha's rule is the Vavilov rule, which states that the quantum yield of luminescence is generally independent of the excitation wavelength. [4] [7] This can be understood as a consequence of the tendency – implied by Kasha's rule – for molecules in upper states to relax to the lowest excited state non-radiatively.
Fluorescence microscopy relies upon fluorescent compounds, or fluorophores, in order to image biological systems.Since fluorescence and phosphorescence are competitive methods of relaxation, a fluorophore that undergoes intersystem crossing to the triplet excited state no longer fluoresces and instead remains in the triplet excited state, which has a relatively long lifetime, before ...