Electrons, high-energy transfer

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 analytical usefulness of this reaction, stems mainly from that fact that the electrochemically generated Ru(bpy)33+ species can be reduced by a large number of potential analyte compounds, or their electrochemical derivatives, via high-energy electron transfer reactions, to produce the Ru(bpy)32+ excited species, without the need for an electrochemical reduction step. The converse is also true. The reduction of peroxodisulfate (S2082-) for example, in the presence of Ru(bpy)32+, produces the Ru(bpy)32+ excited species and an ECL emission, from the reaction of Ru(bpy)3+ and S04 [20], Although this latter system has been used for the determination of both Ru(bpy)32+ [21] and S2082- [22], the vast majority of analytical applications use the co-oxidation route. 

Electrogenerated CL (also called ECL and abbreviated as ECL) is the process in accordance with which, species generated at electrodes undergo high-energy electron-transfer reactions to form excited states that emit light (Scheme 1.4) [13]. 

The conformational changes also explain the slow electron transfer between two hydrazine moieties separated by a bridge (Gleiter et al. 1996, Nelsen et al. 1975, 1976, 1997b). In all the cases, the inner reorganization energy is high when electron transfer occurs. Particularly, when the unpaired electron is transferred from the planar hydrazine cation-radical unit to the tetrahedral... 

The Ea for the dissolution of hematite by mercapto carboxylic acids in acid media in the presence of UV radiation was lower (64 5 kj mol ) than that for dissolution in the absence of radiation (94 8 kJ mol ) (Waite et al. 1986). The reaction in both cases was considered to involve formation of an intermediate organic-Fe surface complex which decomposed as a result of intramolecular electron transfer to release Fe". UV irradiation enhanced the decomposition of the surface complex either through excitation of the ligand field states associated with the free electrons on the S atoms, or through high energy charge transfer states. 

When hydroxyl radical is reacting with inorganic species, electron transfer will occur after aqueous solutions are irradiated with high energy electrons. For example, halogen ions (X-) will react with hydroxyl radical as follows ... 

---