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Titolo:
Mechanism of TMPD photolysis in alcohols. Spin-dependent ion recombinationand photoconductivity
Autore:
Tadjikov, B; Smirnov, S;
Indirizzi:
New Mexico State Univ, Dept Chem & Biochem, Las Cruces, NM 88003 USA New Mexico State Univ Las Cruces NM USA 88003 m, Las Cruces, NM 88003 USA
Titolo Testata:
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
fascicolo: 2, volume: 3, anno: 2001,
pagine: 204 - 212
SICI:
1463-9076(2001)3:2<204:MOTPIA>2.0.ZU;2-0
Fonte:
ISI
Lingua:
ENG
Soggetto:
PHOTOINDUCED ELECTRON-TRANSFER; GEMINATE RECOMBINATION; LASER PHOTOLYSIS; IONIZATION; DYNAMICS; PAIR; SOLVENTS; POLYMERS; MOTION; DIFFUSION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
34
Recensione:
Indirizzi per estratti:
Indirizzo: Tadjikov, B New Mexico State Univ, Dept Chem & Biochem, Las Cruces, NM 88003 USA New Mexico State Univ Las Cruces NM USA 88003 s, NM 88003 USA
Citazione:
B. Tadjikov e S. Smirnov, "Mechanism of TMPD photolysis in alcohols. Spin-dependent ion recombinationand photoconductivity", PHYS CHEM P, 3(2), 2001, pp. 204-212

Abstract

Photolysis of N,N,N',N'-tetramethyl-1,4-phenylenediamine (TMPD) in liquid alcohols was studied by means of a time-resolved transient conductivity technique and the influence of an external magnetic field. We have shown that no single-photon ionization of TMPD occurs at energies up to 5.5 eV. Instead, the observed photocurrent is a result of diffusion assisted ion pair formation via quenching of excited (TMPD)-T-3* molecules in their triplet state by electron-accepting solutes. Quenching of the singlet excited state (TMPD)-T-1*, on the other hand, leads to fast recombining singlet ion pairs with no resulting free ion current. Competition between the two processes is affected by the external magnetic field and is observed as a magnetic fieldeffect on the photocurrent. The rate constants of quenching of the singletand triplet excited states of TMPD* by acetone in isopropanol were found to be 3.2 x 10(9) M-1 s(-1) and 2.5 x 10(8) M-1 s(-1), respectively. The quantum yield of free ions originating from the (TMPD)-T-3* precursor is closeto 80% in the absence of magnetic field, while the yield from the (TMPD)-T-1* precursor is negligibly small.

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Documento generato il 19/01/20 alle ore 14:36:40