Decay mechanism of triplet sulfur dioxide molecules formed by intersystem crossing in the flash photolysis of sulfur dioxide (2400-3200 Ang.)

1971 ◽  
Vol 93 (11) ◽  
pp. 2581-2587 ◽  
Author(s):  
Jack G. Calvert ◽  
Kiyoshi Otsuka
Keyword(s):  
Sulfur Dioxide ◽  
Flash Photolysis ◽  
Intersystem Crossing ◽  
Decay Mechanism

Electron transfer sensitized photolysis of 'onium salts

1988 ◽  
Vol 66 (2) ◽  
pp. 319-324 ◽  
Author(s):  
R. J. DeVoe ◽  
M. R. V. Sahyun ◽  
Einhard Schmidt ◽  
N. Serpone ◽  
D. K. Sharma
Keyword(s):  
Electron Transfer ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Quantitative Model ◽  
Intersystem Crossing ◽  
Single Electron Transfer ◽  
Onium Salts ◽  
Encounter Complex ◽  
Back Electron Transfer

We have studied the anthracene-sensitized photolyses of both diphenyliodonium and triphenylsulphonium salts in solution using both steady-state and laser flash photolysis techniques. Photoproducts, namely, phenylated anthracenes along with iodobenzene or diphenylsulphide, respectively, are obtained from both salts with quantum efficiencies of ca. 0.1 at 375 nm. We infer the intermediacy of diphenyliodo and triphenylsulphur radicals formed by single electron transfer from the singlet-excited anthracene. We have developed a quantitative model of this chemistry, and identify the principal sources of inefficiency as back electron transfer, which occurs at nearly the theoretically limiting rate, intersystem crossing from the initially formed sensitizer–'onium salt encounter complex, and in-cage radical recombination.

scholarly journals Complex formation between 3;3´-diethylthiacarbocyanine iodide and DNA and its investigation in aqueous solution

1999 ◽  
Vol 1 (1) ◽  
pp. 35-39 ◽  
Author(s):  
M. Y. Anikovsky ◽  
A. S. Tatikolov ◽  
V. A. Kuzmin
Keyword(s):  
Aqueous Solution ◽  
Quantum Yield ◽  
Absorption Spectra ◽  
Flash Photolysis ◽  
Equilibrium Constants ◽  
Intersystem Crossing ◽  
Differential Absorption ◽  
Dna Concentration ◽  
Kinetics Of ◽  
Formation Of Complexes

The binding of 3;3′-diethylthiacarbocyanine iodide (DTCC) with molecules of DNA was investigated by different photochemical methods. Absorption spectra were investigated under various concentration of DNA. Isosbestic points observed in these spectra are attributable to existence of two different complexes DTCC with DNA. Equilibrium constants of the formation of complexes I and II were determined (K1≈106M−1,K2≈5×104M−1accordingly). Differential absorption spectra of two photoisomers of DTCC were obtained by flash photolysis method; it was found that the quantum yield of the short-lived photoisomer decreases and the quantum yield of the second long-lived photoisomer builds up with the increase in the DNA concentration. Kinetics of interaction between the triplet state of the dye and oxygen were investigated under various concentration of DNA. The growth of the quantum yield of fluorescence and intersystem crossing was observed with the increase in the DNA concentration.

scholarly journals A Laser Photolysis Study of Triplet Lifetimes and of Triplet–Triplet Annihilation Reactions of Phthalocyanins in DMSO Solutions (Etude des Durées de Vie du Triplet et des Réactions d'Annihilation Triplet–Triplet de Phthalocyanines dans le DMSO par Photolyse Laser)

1988 ◽  
Vol 8 (1) ◽  
pp. 1-11 ◽  
Author(s):  
M. G. Debacker ◽  
O. Deleplanque ◽  
B. Van Vlierberge ◽  
F. X. Sauvage
Keyword(s):  
Charge Separation ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Reducing Agent ◽  
Dilute Solution ◽  
Concentrated Solutions ◽  
Decay Mechanism ◽  
First Order ◽  
Annihilation Reactions

Triplet decay of Mg and Zn phthalocyanins have been studied by laser flash photolysis as a function of concentration. The triplet decay mechanism changes from a near first order in dilute solution to an almost second order in concentrated solutions. This is interpreted in terms of triplet–triplet recombinaison. With the help of a reducing agent, it is shown that the triplet–triplet reaction can lead to charge separation.La décroissance des états excités triplet des phthalocyanines de Mg et de Zn a été étudiée par photolyse éclair laser en fonction de la concentration. Le mécanisme de décroissance du triplet passe d'un premier ordre presque idéal en solution diluée à un quasi second ordre en solution concentrée. Ceci s'explique par une recombinaison triplet–triplet. A l'aide d'un réducteur, la réaction triplet–triplet peut conduire à une séparation de charges.

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