is the sum of all the decay rates of the excited state. Other rates of decay of the excited state are caused by mechanisms other than photon emission and are therefore often referred to as “non-radiological rates”, which may include: dynamic collision extinction, near-field dipole-dipole interaction (or resonance energy transfer), internal conversion, and intersystem crossing. Thus, when the speed of a path changes, the lifetime of the excited state and the quantum efficiency of fluorescence are affected. Another adaptive use of fluorescence is to produce orange and red light from the blue ambient light of the photic zone to support vision. Red light can only be seen over short distances due to the attenuation of red light wavelengths by water. [38] Many species of fish that fluorescent are small, live in groups or benthic/aphotic and have striking patterns. This pattern is caused by fluorescent tissue and is visible to other members of the species, but the pattern is invisible on other visual spectra. These intraspecific fluorescence patterns also coincide with species signaling. The patterns present in dark circles to indicate directional dependence on an individual`s gaze, and along the fins to indicate directional dependence on an individual`s movement. [38] Recent research suggests that this red fluorescence is used for private communication between members of the same species. [29] [32] [38] Due to the importance of blue light in the depths of the ocean, red light and light of longer wavelengths are confused, and many predatory reef fish have little or no sensitivity to light at these wavelengths.

Fish such as fairy wrasse, which have developed visual sensitivity at longer wavelengths, are able to display red fluorescence signals that form a high contrast with the blue environment and are noticeable by congeners at short distances, but are relatively invisible to other common fish that have reduced sensitivity to long wavelengths. Thus, fluorescence can be used as adaptive signaling and intra-species internal communication in reef fish. [38] [39] Phosphorescence is similar to fluorescence in its light wavelength requirements as a supplier of excitation energy. The difference here lies in the relative stability of the energized electron. Unlike fluorescence, phosphorescence allows the electron to maintain its stability and emit light that continues to “glow in the dark” even after the stimulating light source has been removed. [24] For example, incandescent stickers are phosphorescent in the dark, but no truly biophosphate animals are known. [28] Several species of mantis shrimp, which are stomatopod crabs, including Lysiosquillina glabriuscula, have yellow fluorescent markings along their antennae scales and shells that pose males in case of threats to predators and other males. The display includes lifting the head and chest, distributing distinctive appendages and other maxillipeds, and lengthening the distinctive oval antennae scales laterally, making the animal appear larger and highlighting its yellow fluorescent markings. In addition, the fluorescence of mantis shrimp with increasing depth represents a greater part of the available visible light.

During mating rituals, mantis shrimp actively fluorescent, and the wavelength of this fluorescence coincides with the wavelengths detected by their ocular pigments. [47] In other words, Grew appears to have observed the fluorescence characteristic of chlorophyll. Nglish: The translation of fluorescence for Spanish-speaking anthracene is a white crystalline hydrocarbon with bluish fluorescence that melts at 213°C and boils above 360°C. Many types of calcite and amber fluoresce under short-wave UV, long-wave UV and visible light. Rubies, emeralds and diamonds show red fluorescence under long-wave, blue and sometimes green UV light; Diamonds also emit light under X-rays. Fluorescence has many practical applications, including mineralogy, gemology, medicine, chemical sensors (fluorescence spectroscopy), fluorescence labeling, dyes, biological detectors, cosmic ray detection, vacuum fluorescence screens, and cathode ray tubes. Its most common daily application is in fluorescent (gas discharge) lamps and LED lamps, in which fluorescent coatings convert UV or blue light into longer wavelengths, resulting in white light that may even be indistinguishable from that of traditional but energy-inefficient incandescent lamps. Bony fish that live in shallow waters usually have good color perception because they live in a colorful environment. Thus, in shallow-water fish, red, orange and green fluorescence most likely serves as a means of communication with congeners, especially given the large phenotypic variance of the phenomenon. [32] Mirabilis jalapa flower contains purple fluorescent betacyans and yellow fluorescent betaxanthins.

Under white light, parts of the flower that contain only betaxanthins appear yellow, but in areas where betaxides and betayanins are present, the visible fluorescence of the flower fades due to the internal mechanisms of light filtering. It has already been suggested that fluorescence plays a role in pollinator attraction, but it was later found that the visual signal of fluorescence is negligible compared to the visual signal of light reflected by the flower. [64] There are several general regulations dealing with fluorescence. Each of the following rules has exceptions, but they are useful guidelines for understanding fluorescence (these rules do not necessarily apply to the absorption of two photons). The ground state of most molecules is a singlet state called S0. A notable exception is molecular oxygen, which has a triplet ground state. The absorption of a photon of the energy h ν e x {displaystyle hnu _{ex}} gives an excited state of the same multiplicity (spin) of the ground state, usually a singlet (Sn with n > 0). In solution, states with n > 1 rapidly relax at the lowest vibrational level of the first excited state (S1) by transferring energy to solvent molecules through non-radiating processes, including internal conversion followed by vibrational relaxation, in which energy is dissipated as heat. [12] Therefore, fluorescence most often occurs from the first excited state of the singlet, S1. Fluorescence is the emission of a photon that accompanies the relaxation of the excited state in the ground state. Fluorescence photons are of lower energy ( h ν e m {displaystyle hnu _{em}} ) compared to the energy of the photons used to generate the excited state ( h ν e x {displaystyle hnu _{ex}} ) Spiders fluorescent under UV light and have a wide variety of fluorophores.

Remarkably, spiders are the only known group in which fluorescence is “taxonomically widespread, expressed in a variable manner, evolutionarily unstable, and probably in the process of selection and potentially of ecological importance for intraspecific and interspecific signaling.” A study by Andrews et al. (2007) shows that fluorescence has evolved several times through spider taxa, with new fluorophores developing during spider diversification. In some spiders, ultraviolet signals are important for predator-prey interaction, intraspecific communication, and camouflage with matching fluorescent flowers. Different ecological contexts could promote inhibition or improvement of fluorescence expression, depending on whether fluorescence helps spiders be cryptic or makes them more visible to predators. Therefore, natural selection could act on the expression of fluorescence in spider species. [59] The fluorescence quantum yield reflects the efficiency of the fluorescence process. It is defined as the ratio between the number of photons emitted and the number of photons absorbed. [13] [12] Fluorescence in minerals is caused by a variety of activators.