Term phosphorescence

Edmond Becquerel (1820-1891) was the nineteenth-century scientist who studied the phosphorescence phenomenon most intensely. Continuing Stokes s research, he determined the excitation and emission spectra of diverse phosphors, determined the influence of temperature and other parameters, and measured the time between excitation and emission of phosphorescence and the duration time of this same phenomenon. For this purpose he constructed in 1858 the first phosphoroscope, with which he was capable of measuring lifetimes as short as 10-4 s. It was known that lifetimes considerably varied from one compound to the other, and he demonstrated in this sense that the phosphorescence of Iceland spar stayed visible for some seconds after irradiation, while that of the potassium platinum cyanide ended after 3.10 4 s. In 1861 Becquerel established an exponential law for the decay of phosphorescence, and postulated two different types of decay kinetics, i.e., exponential and hyperbolic, attributing them to monomolecular or bimolecular decay mechanisms. Becquerel criticized the use of the term fluorescence, a term introduced by Stokes, instead of employing the term phosphorescence, already assigned for this use [17, 19, 20], His son, Henri Becquerel (1852-1908), is assigned a special position in history because of his accidental discovery of radioactivity in 1896, when studying the luminescence of some uranium salts [17]. 

Generation of excited triplet states is normally achieved as a result of (iv) above and, once formed, they may decay by processes analogous to (i)—(iv) with the obvious distinction that radiative decay of triplet states is termed phosphorescence, and that radiationless transition of excited triplet states, back to ground singlet states, involves intersystem crossing. Whilst there are very many mechanisms whereby so called quenching of excited states may occur (1,2), and a full discussion is outside the scope of this article, a large part of the review will be... 

ES2 has its own decay processes including radiative (k, termed phosphorescence) and non-radiative deactivation (k ), unimolecular reaction to product(s) (kp) and bimolecular quenching by energy or electron transfer (kq) to another species. For this model the ES2 lifetime is defined by... 

The term phosphorescence refers to delayed emission of light as a result of deexcitation of atoms or molecules. Phosphorescent half-lives may extend to hours. This source of background may originate in phosphorescent substances contained in the glass of the phototube, the walls of the sample holder, or the sample itself. 

The term phosphorescence comes from the Greek fee = light (genitive case < >otoq photon) and opeiv = to bear (Scheme 1.1). Therefore, phosphor means which bears light . The term phosphor has indeed been assigned since the Middle... 

A phosphor screen is used to convert electron energy into radiant energy in a CRT display device. The screen is composed of a thin layer of luminescent crystals, phosphors, that emit Kght when bombarded by electrons. This property is referred to as cathodoluminescence. It occurs when the energy of the electron beam is transferred to electrons in the phosphor crystal. The property of Kght emission during excitation is termed fluorescence, and that immediately after excitation is removed is termed phosphorescence. 

Backstrom measured the quenching of the emission (called for the moment long-lived fluorescence, although in later papers he used the term phosphorescence) [35] by alcohols, amines, and phenols and obtained quenching constants from 2.6 X 10 s (methanol) to 5.9 x 10 s (hydroquinone). Recalling... 

For longer reemission times, the term phosphorescence is used. 

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