Luminescence mechanism

Schuster, G. B. (1979). Chemiluminescence of organic peroxides. Conversion of ground-state reactants to excited-state products by chemically initiated electron-exchange luminescence mechanism. Acc. Chem. Res. 12 366-373. 

It should be noted that other structures, such as siloxene [De6] or polysilane [Ta4], that have been proposed to play a role in the luminescence mechanism of PS have also been studied on a theoretical level. 

The molecular recombination model. Absorption of a photon and its radiative reemission occurs in chemical compounds such as siloxenes [Br6], polysilanes [Ta4] or silicon hydrides [Pr6]. This luminescence mechanism is independent of whether or not QC is present in PS. 

Sensitized Luminescence. Through the incorporation of foreign ions (e.g., Tl+, Ga+, In+) into the crystal lattice, further luminescence centers are formed. The emission spectra are characteristic for the individual foreign ions. The complicated luminescence mechanism is described in [5.408]. 

Further examination of "reductive oxidation" ECL using polyaromatic compounds in non-aqueous media has revealed three signific ant features of the luminescence mechanism (10). First, the cyclic voltammograms fojj the reduction of the polyaromatic compounds in the presence of S2O8 were of a highly catalytic type. Second, the efficiency of ECL was qualitatively dependent on the stability of the aromatic radical cation rather than of the aromatic radical anion. Third, the importance of the aromatic radical cation ion in the mechanism for the formation of excited states was illustrated using a tertiary reactant system. The results of these studies are summarized below. 

One final series of quinoline-based ligand complexes (in which there is no steric effect) has been found to be rather unusual248,251,252. The ligand i-bq is expected to behave as a substituted bpy. [Ru(i-bq)3]2+ has a potential (III/II) of 1.12 v indicating less stabilization of ruthenium(II) than in [Ru(bpy)3]2+ 252). The epsilon value is nearly twice that of [Ru(bpy)3]2+, suggesting that the compound should be an efficient emitter. It turns out that in this complex an entirely different luminescence mechanism is operative. [Ru(i-bq)3]2+ shows ligand-centered luminescence, which is unusual in a ruthenium com-... 

The nature of the additional luminescence in systems with C6o fullerene-water interface remains unknown yet, but we can just advocate that the role of water (or maybe oxygen ion) is essential to formation of this luminescence mechanism. It reflects an existence of high interaction between water and Cgo fullerene molecules. 

Dixon and Schuster (1979, 1981) have investigated both the thermal and electron-donor induced reactions of 1-phenylethyl peroxyacetate [28] and a series of substituted 1-phenylethyl peroxybenzoates [29a-29e]. They report the direct generation of electronically excited states from unimolecular thermo-lyses, as well as generation of light by the chemically initiated electron-exchange luminescence mechanism. 

In this section, historic aspects of luminescent materials will be discussed first, followed by a short treatment of luminescence mechanisms and luminescence excitation schemes. Thereafter, devices based on luminescent materials and the way in which luminescent materials determine their operational performance will be discussed. Preparational aspects of luminescent materials will be described and then this section will end with an outlook. 

Recently, attention have been paid to the properties nano-porous silicon. Canham observed the strong luminescence from porous siliconl. A number of photo-luminescent (PL) and/or electro-luminescent(EL) devices have been reported. Steiner et al. reported not only red/orange luminescence but also green/blue electro luminescence from the devicesI L The quantum confinement or the localized centers at the surface have been reported as the luminescence mechanism. They suggested that the luminescence mechanism depends of the fabrication process of the porous silicon s ll. 

The luminescence of bulk silicon is orders of magnitude weaker than that of oxidized nc-Si and results fi om interband recombination. In this luminescence mechanism localization plays no role. 

S. M. Prokes, Study of the luminescence mechanism in porous silicon structures, J. Appl. Phys. 73(1), 40, 1993. 

Takano Y, Tsunesada T, Isobe H, Yoshioka Y, Yamaguchi K, and Saito I. Theoretical studies of decomposition reactions of dioxetane, dioxetanone, and related species. CT induced luminescence mechanism revisited. Bull Chem Soc Jpn 1999 72 213-25. 

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