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Titolo:
Primary photophysical properties of A2E in solution
Autore:
Lamb, LE; Ye, T; Haralampus-Grynaviski, NM; Williams, TR; Pawlak, A; Sarna, T; Simon, JD;
Indirizzi:
Jagiellonian Univ, Jan Zurzycki Inst Mol Biol, Dept Biophys, PL-31120 Krakow, Poland Jagiellonian Univ Krakow Poland PL-31120 iophys, PL-31120 Krakow, Poland Duke Univ, Dept Chem, Durham, NC 27708 USA Duke Univ Durham NC USA 27708Duke Univ, Dept Chem, Durham, NC 27708 USA Duke Univ, Med Ctr, Dept Biochem, Durham, NC 27710 USA Duke Univ Durham NC USA 27710 Med Ctr, Dept Biochem, Durham, NC 27710 USA Duke Univ, Med Ctr, Dept Ophthalmol, Durham, NC 27710 USA Duke Univ Durham NC USA 27710 Ctr, Dept Ophthalmol, Durham, NC 27710 USA
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 46, volume: 105, anno: 2001,
pagine: 11507 - 11512
SICI:
1520-6106(20011122)105:46<11507:PPPOAI>2.0.ZU;2-R
Fonte:
ISI
Lingua:
ENG
Soggetto:
RETINAL-PIGMENT EPITHELIUM; LIPOFUSCIN FLUOROPHORE; AGE PIGMENT; MACULAR DEGENERATION; ELECTRON-TRANSFER; SINGLET-STATE; CELLS; A2-E; PHOTOCHEMISTRY; FLUORESCENCE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
39
Recensione:
Indirizzi per estratti:
Indirizzo: Sarna, T Jagiellonian Univ, Jan Zurzycki Inst Mol Biol, Dept Biophys, Al Mickiewicza 3, PL-31120 Krakow, Poland Jagiellonian Univ Al Mickiewicza 3 Krakow Poland PL-31120 Poland
Citazione:
L.E. Lamb et al., "Primary photophysical properties of A2E in solution", J PHYS CH B, 105(46), 2001, pp. 11507-11512

Abstract

Time-resolved spectroscopic techniques are used to determine the primary photoprocesses of A2E in solution. Comparison of the absorption and excitation spectrum of A2E in methanol solution indicates excitation 400 nm populates the S-2 excited state. Transient absorption signals decaying with a timeconstant of 0.9 ps were observed probing around 800 nm. These signals are attributed to the S-2-->S-n transition and reveal the S-2-->S-1 relaxation occurs on the subpicosecond time scale. Transient absorption data probing at shorter wavelengths (480 and 550 nm) are attributed to the S-1-->S-n absorption. These signals exhibit an exponential decay with a time constant of 11 and 13 ps, respectively. Time-resolved emission measurements of the corresponding S-0<--S-1 decay reveal a nonexponential decay; however, > 95 % ofthe signal amplitude is described by an exponential decay with a time constant of 12.4 ps. Both time-resolved emission and absorpti.on experiments therefore indicate repopulation of the ground electronic state occurs with a time constant of similar to 12 ps. A weak transient absorption probing in the blue (400 nm) persists onto the nanosecond time scale and is attributed to the T-1-->T-n absorption of A2E. Photoacoustic spectroscopy establishes the quantum yield for intersystem crossing of A2E in methanol solution is at most 0.03. The emission quantum yield of A2E in ethanol is determined to be 0.01, and so, nonradiative relaxation is the dominant primary event. Thequantum yield for the generation of singlet molecular oxygen following 355mn excitation of A2E in acetonitrile was determined to be 0.02, consistentwith a low production of the excited triplet state. These results establish A2E is not an efficient photogenerator of reaction oxygen species in solution.

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Documento generato il 28/01/20 alle ore 21:30:50