Solution electrochemiluminescent

Most solution-electrochemiluminescence emission studies have been made by applying 3-10 V across platinum electrodes, frequently... 

Nishimura K, Hamada Y, Tsujioka T, Shibata K, Fuyuki T (2001) Solution electrochemiluminescent cell using tris(phenylpyridine) iridium. Jap J App Phy 40 (Part 2, No. 9A/B) L945-L947. doi 10.1143/JJAP.40.L945... 

Electrochemiluminescence Emission occurring in solution, from an electronically excited state produced by high-energy electron transfer reactions Electrogenerated chemiluminescence Emission produced at an electrode surface Oxyluminescence Emission from polymers caused by oxidative processes (presence of oxygen is required)... 

Electrogenerated chemiluminescence (ECL) is the process whereby a chemiluminescence emission is produced directly, or indirectly, as a result of electrochemical reactions. It is also commonly known as electrochemiluminescence and electroluminescence. In general, electrically generated reactants diffuse from one or more electrodes, and undergo high-energy electron transfer reactions either with one another or with chemicals in the bulk solution. This process yields excited-state molecules, which produce a chemiluminescent emission in the vicinity of the electrode surface. 

The influence of impurities on electrochemiluminescence emission behavior has been difficult to ascertain. The best quantum yield of emission under annihilative conditions thus far achieved is about 1 %.63 The preannihilative emission is one to two orders of magnitude less intense.11 As the concentration of fluorescer in emitting systems is ca. 10 3M, as low a concentration of impurity as 10 7M may be responsible for the entire emission. Investigations thus far conducted have tacitly accepted such impurity levels in these solutions and have concentrated on inferring their action by observing the effects of additives... 

Feldberg68,69 has made a valuable analysis of the relationship of the light produced in a double potential step electrochemiluminescence experiment to the current, time, and kinetic parameters involved. The analysis presumes that the reaction which produces excited states is cation-anion radical annihilation which occurs when the radical ions, separately produced, diffuse together in the solution near the electrode. The processes that Feldberg initially considered were eqs. (7)—(13). The assumptions involved are that decay of the excited state... 

As described above, spectroelectrochemical methods are useful in studying the reactivity of radical anions and cations in non-aqueous solutions. Related to this, electrochemiluminescence (ECL), which is often caused by the reaction between radical... 

Photonic electrochemistry, taken in its most general sense, involves the intimate interaction of light with electrochemical processes. Thus, piocesses in which illumination of the electrode-electrolyte interface produces charge-transfer events as well as electrochemical reactions that produce light as a product (electrochemiluminescence, ECL) fall in this category. A third related area is the elec-troanalytical detection of transient species formed by a photochemical process which takes place in solution. Techniques such as spectroelectrochemistry are excluded from consideration, since they utilize photons as a nonperturbing probe of purely electrochemical processes. 

IET serves as a theoretical basis not only for fluorescence and photochemistry but also for photoconductivity and for electrochemiluminescence initiated by charge injection from electrodes. These and other related phenomena are considered. The kinetics of luminescence induced by pulse and stationary excitation is elucidated as well as the light intensity dependence of the fluorescence and photocurrent. The variety and complexity of applications proves that IET is a universal key for multichannel reactions in solutions, most of which are inaccessible to conventional (Markovian) chemical kinetics. 

Elect regenerated chemiluminescence (ECL) — (-> electrochemiluminescence or electrochemically generated chemiluminescence) The generation of light in an electrochemical cell by an energetic electron transfer reaction, often between radical ions in an aprotic solvent. In a typical experiment in a solution of rubrene (R) and N,N,N, N -tetramethyl-p-phenylenediamine (TMPD) in dimethylformamide initially radical anions of rubrene are formed by electroreduction... 

The [Ru(bpy)3] + and [Ru(bpy)3]+ complexes can be generated by another chemical reaction from [Ru(bpy)3] +, for example with Pb02 or Mg, respectively. The whole chemiluminescent reaction can then be run cyclic, as a catalytic process, shown Figure 8. Alternatively, the oxidized or reduced Ru complex is generated electrochemically at an electrode inserted to the solution, giving rise to electrochemiluminescence. 

Figure 14. Sonoelectrochemiluminescence of tris-bipyridine ruthenium (II) dichloride ((Ru(bpy)3]Cl2) at platinum in aqueous oxalate solution. Potentiostatic control +1.2 V (SCE). (a) Background zero line, (b) Sonoluminescence from 40-kHz probe, no applied potential, (c) Electrochemiluminescence at +1.2 V (SCE), silent, (d) Sonoelec-trochemiluminescence at 1.2 V (SCE) and ultrasound (40-kHz probe). (Taken from reference 209).

Ultrasound influences multiphase systems such as the production of microemulsions. It is useful in electrosynthesis involving immiscible materials—this effect has been particularly exploited for several applications in environmental science. Ultrasound can also enhance electrochemiluminescence systems, and has been applied to many other aspects of electrochemistry, including the as yet unexplained benefits of pre-treating electrolyte solutions. It has even been proposed to enhance electrochemical cold-fusion . 

Figure 9. Photoluminescence (a) and electrochemiluminescence (b) spectra of Pt(tpy)2 in DMF solution. From Ref. 118 with permission of American Chemical Society.

The spectrum of the triboluminescence (i.e. emission caused by mechanical stress) of U0a(N03)2,6H20 is similar to that for photo-induced luminescence.167 Possible causes for this effect are electrical excitation (i.e. pressure-induced electrochemiluminescence), intermolecular interactions, and intramolecular deformations. Arguments are presented to show that the third mechanism is not important in this case. Other relevant publications are concerned with electrochemiluminescence of UOa8+ in perchloric acid,168 170 171 173 174 absorption and luminescence spectra of UOa2+ in solution,16 and detailed analyses of the emission spectrum of crystalline UOa2+ salts at low temperatures.170-174... 

A fiber-optic electrode was fabricated for the simultaneous generation and transmission of electrochemical luminescence by preparing a transparent electrode on the optical and surface of a fiber-optic. The opto-electrochemical properties of the micro-optical device were characterized in solutions containing the compounds required for luminol luminescence. The validity of sensitive measurement of electrochemiluminescence to be employed in a homogeneous immunoassay was evaluated by using potential step excitation of luminol in the presence and in the absence of hydrogen peroxide. 

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