Types of Luminescence

In addition to ECL, light can be generated by a wide variety of luminescent processes (Table 13.1). Of them, both ECL and chemiluminescence (CL) involve the production of 

Lyoluminescence Excitation induced by dissolution of an irradiated or other energy-donating solid (89, 90) 

Sonoluminescence Excitation of compounds by ultrasonication, either by energy transfer from the intrinsic SL centers of water or by chemical excitation by hydroxyl radicals and atomic hydrogen (91-110) 

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Fluorescence and phosphorescence are types of luminescence, ie, emission attributed to selective excitation by previously absorbed radiation, chemical reaction, etc, rather than to the temperature of the emitter. Laser-iaduced and x-ray fluorescence are important analytical techniques (see... 

Chemical studies on fish luminescence have been hampered by difficulties in obtaining specimens and the minute sizes of the luminous organs and photophores. Despite the setbacks, it might be possible to find out the basic nature of a luminescence reaction when coelenterazine (or Cypridina luciferin) is utilized in the luminescence. Once the basic nature of the luminescence reaction is found, then further details might become available by comparison with an organism having the same type of luminescence system. 

Haneda, Y., and Johnson, F. H. (1962a). The photogenic organs of Parapriacanthus beryciformes Franz and other fish with the indirect type of luminescent system./. Morph. 110 187-198. 

Shimomura, O., and Johnson, F. H. (1968a). Light emitting molecules in a new photoprotein type of luminescence system from the euphausiid shrimp Meganyctiphanes norvegica. Proc. Natl. Acad. Sci. USA 59 475-477. 

Luminescence is an emission of ultraviolet, visible or infrared photons from an electronically excited species. The word luminescence, which comes from the Latin (lumen = light) was first introduced as luminescenz by the physicist and science historian Eilhardt Wiedemann in 1888, to describe all those phenomena of light which are not solely conditioned by the rise in temperature , as opposed to incandescence. Luminescence is cold light whereas incandescence is hot light. The various types of luminescence are classified according to the mode of excitation (see Table 1.1). 

Luminescence is, in some ways, the inverse process to absorption. We have seen in the previous section how a simple two-level atomic system shifts to the excited state after photons of appropriate frequency are absorbed. This atomic system can return to the ground state by spontaneous emission of photons. This de-excitation process is called luminescence. However, the absorption of light is only one of the multiple mechanisms by which a system can be excited. In a general sense, luminescence is the emission of light from a system that is excited by some form of energy. Table 1.2 lists the most important types of luminescence according to the excitation mechanism. 

This book is primarily concerned with those phenomena where the emission of colour is the technologically important outcome of luminescence. The main types of luminescence falhng within this category and some of their applications are summarised in Table 3.1. 

For chromium containing lilac chlorite two types of luminescence were observed at 15 K phosphorescence at 14,518 and 1,547 cm with a decay time of 60 ps and a fluorescence band at about 13,850-13,500 cm with a decay time of several microseconds. For green chlorite weak fluorescence at 13,900 cm and phosphorescence at 14,320 and 14,665 cm were observed at room tern-... 

The second type of luminescence can be observed under electroreduction of organic substances (Dehmlow et al., 1975 Luttmer and Bard, 1979). This luminescence is shown schematically in Fig. 37. An electron from the conduction band passes into the excited (for instance, triplet) state of the organic substance 3R, which is then deactivated returning to the ground state... 

Semiconductor band-gap luminescence results from excited electrons recombining with electron vacancies, holes, across the band gap of the semiconductor material. Electrons can be excited across the band gap of a semiconductor by absorption of light, as in photoluminescence (PL), or injected by electrical bias, as in electroluminescence (EL). Both types of luminescence have been used in chemical sensing applications [1,3]. 

BLUE GLOW. A type of luminescence emitted by certain metallic oxides, when heated. A blue glow is normally seen in electron tubes containing mercury vapor, arising from the ionization of the molecules in the mercury vapor. 

The luminescence process itself involves 11) absorption of energy (2) excitation, and tT) emission of energy, usually in the form of radiation in the visible portion of Ihe spectrum. The type of luminescence is usually defined by the excitation means, i.e.. irn/W luminesce nee where excitation is hy cathode rays, as in a television kinescope. The most commonly encountered types of luminescence arc listed in Table I. 

One more type of luminescence phenomena associated with electron tunneling was suggested in ref. 72. In the scheme of Fig. 17, this transition is denoted by b. 

Table 5.1 Types of luminescence and their mode of excitation...

However, in another approach, it is just becoming apparent that some types of luminescent metal complexes display spectroscopic properties that facilitate the monitoring of kinetic events during a variety of industrially important poly-... 

CIEEL (Chemically initiated Electron Exchange Luminescence) A type of luminescence resulting from a thermal electron-transfer reaction. Also called catalyzed chemiluminescence. 

If, however, the population of the energy state 2 ii> a consequence of a non-thermal process, then the emission of radiation as a result of a transition from 2 to 1 is referred to as luminescence. There are different types of luminescence ... 

Types of Luminescent Rare Earth Complexes for Bioimaging... 

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