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Title: Electrochemiluminescence  
Author: World Heritage Encyclopedia
Language: English
Subject: Photoelectrochemistry, Light-emitting electrochemical cell, ECL, Allen J. Bard, Luminescence
Collection: Luminescence, Photoelectrochemistry
Publisher: World Heritage Encyclopedia


Electrochemiluminescence or electrogenerated chemiluminescence (ECL) is a kind of luminescence produced during electrochemical reactions in solutions. In electrogenerated chemiluminescence, electrochemically generated intermediates undergo a highly exergonic reaction to produce an electronically excited state that then emits light upon relaxation to a lower-level state. This wavelength of the emitted photon of light corresponds to the energy gap between these two states.[1] ECL excitation can be caused by energetic electron transfer (redox) reactions of electrogenerated species. Such luminescence excitation is a form of chemiluminescence where one/all reactants are produced electrochemically on the electrodes.[2]

ECL is usually observed during application of potential (several volts) to electrodes of electrochemical cell that contains solution of luminescent species (polycyclic aromatic hydrocarbons,[3] metal complexes, Quantum Dots or Nanoparticles[4]) in aprotic organic solvent (ECL composition). In organic solvents both oxidized and reduced forms of luminescent species can be produced at different electrodes simultaneously or at a single one by sweeping its potential between oxidation and reduction. The excitation energy is obtained from recombination of oxidized and reduced species.

In aqueous medium which is mostly used for analytical applications simultaneous oxidation and reduction of luminescent species is difficult to achieve due to electrochemical splitting of water itself so the ECL reaction with the coreactants is used. In the later case luminescent species are oxidized at the electrode together with the coreactant which gives a strong reducing agent after some chemical transformations (the oxidative reduction mechanism).


ECL proved to be very useful in analytical applications as a highly sensitive and selective method. It combines analytical advantages of chemiluminescent analysis (absence of background optical signal) with ease of reaction control by applying electrode potential. As an analytical technique it presents outstanding advantages over other common analytical methods due to its versatility, simplified optical setup compared with photoluminescence (PL), and good temporal and spatial control compared with chemiluminescence (CL). Enhanced selectivity of ECL analysis is reached by variation of electrode potential thus controlling species that are oxidized/reduced at the electrode and take part in ECL reaction[5] (see electrochemical analysis).

It generally uses Ruthenium complexes, especially photomultiplier tubes (PMT) or silicon photodiode or gold coated fiber-optic sensors.The importance of ECL techniques detection for bio-related applications has been well established.[6] ECL is heavily used commercially for many clinical lab applications.[7]

See also


  1. ^ Forster RJ, Bertoncello P, Keyes TE (2009). "Electrogenerated Chemiluminescence". Annual Review of Analytical Chemistry 2: 359–85.  
  2. ^ Electrogenerated Chemiluminescence, Edited by Allen J. Bard, Marcel Dekker, Inc., 2004
  3. ^ Valenti, G.; Bruno, C.; Rapino, S.; Fiorani, A.; Jackson, E.A.; Scott, L.T.; Paolucci, F.; Marcaccio, M. (October 2010). "Intense and Tunable Electrochemiluminescence of Corannulene". J. Phys. Chem. C 114 (45): 19467–19472.  
  4. ^ Rampazzo, E.; Bonacchi, S.; Genovese, D.; Juris, R.; Marcaccio, M.; Montalti, M.; Paolucci, F.; Sgarzi, M.; Valenti, G.; Zaccheroni, N.; Prodi, L. (August 2012). "Nanoparticles in metal complexes-based electrogenerated chemiluminescence for highly sensitive applications". Coordination Chemistry Reviews 256 (15-16): 1664–1681.  
  5. ^ Fähnrich, K.A.; Pravda, M.; Guilbault, G. G. (May 2001). "Recent applications of electrogenerated chemiluminescence in chemical analysis". Talanta 54 (4): 531–559.  
  6. ^ Miao, Wujian (2008). "Electrogenerated Chemiluminescence and Its Biorelated Applications". Chemical Reviews 108 (7): 2506–2553.  
  7. ^ Lee, Won-Yong (1997). "Tris (2,2′-bipyridyl)ruthenium(II) electrogenerated chemiluminescence in analytical science". Mikrochimica Acta 127 (1-2): 19–39.  
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