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Titolo:
Metastable electrons, high-mobility solvent anions, and charge transfer reactions in supercritical carbon dioxide
Autore:
Shkrob, IA; Sauer, MC;
Indirizzi:
Argonne Natl Lab, Div Chem, Argonne, IL 60439 USA Argonne Natl Lab Argonne IL USA 60439 ab, Div Chem, Argonne, IL 60439 USA
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 19, volume: 105, anno: 2001,
pagine: 4520 - 4530
SICI:
1520-6106(20010517)105:19<4520:MEHSAA>2.0.ZU;2-U
Fonte:
ISI
Lingua:
ENG
Soggetto:
LASER FLASH-PHOTOLYSIS; PHOTOELECTRON-SPECTROSCOPY; DIFFUSION-COEFFICIENTS; NONPOLAR-SOLVENTS; EXCESS ELECTRONS; INFRARED-SPECTRA; NITROUS-OXIDE; SOLID NEON; FLUIDS; CO2;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
70
Recensione:
Indirizzi per estratti:
Indirizzo: Shkrob, IA Argonne Natl Lab, Div Chem, 9700 S Cass Ave, Argonne, IL 60439 USA Argonne Natl Lab 9700 S Cass Ave Argonne IL USA 60439 60439 USA
Citazione:
I.A. Shkrob e M.C. Sauer, "Metastable electrons, high-mobility solvent anions, and charge transfer reactions in supercritical carbon dioxide", J PHYS CH B, 105(19), 2001, pp. 4520-4530

Abstract

Time-resolved de photoconductivity has been used to observe quasifree electrons and solvent radical anions in supercritical CO2 (rho (c) approximate to 0.468 g/cm(3); T-c approximate to 31 degreesC). The electrons have lifetime tau (e) < 200 ps and mobility mu (e), > 10 cm(2)/(V s). For rho/rho (c)> 0.64, the product mu (e)tau (e) rapidly increases with the solvent density rho, reaching 2.5 x 10(-9) cm(2)/V at rho/rho (c) approximate to 1.82. The mobility of the solvent anions exponentially increases with p, being 2-10 times higher than the mobilities of other ions. The activation energy of the solvent anion migration is 0.46 eV, whereas for solute ions, this energy is less than 20 meV. Electron detachment upon 1.0-3.5 eV photoexcitation of the solvent anion has been observed. The cross section of photodetachment Linearly increases with photon energy above 1.76 eV end exhibits a shoulder at 2.82 eV; the spectrum is similar to photoelectron spectra of (CO2)(n)(-) clusters (n = 6-9) in the gas phase. Both the electrons and solvent anions react with nonpolar electron acceptor solutes whose gas-phase electron affinity (EA(g)) is greater than 0.4 eV. At T = 41 degreesC and rho/rho (c)approximate to 1.77, the rates of the electron attachment and solvent anion scavenging correlate with each other and the solute EA,. Only solutes with EA(g) > 2 eV exhibit diffusion-controlled kinetics. For pip, r 0.85, the scavenging radii of these diffusion-controlled reactions decrease with rho. For O-2, the scavenging of the solvent anion is reversible (DeltaH degreesapproximate to -0.44 eV).

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Documento generato il 21/09/20 alle ore 11:41:14