Electron Photodetachment from Aqueous Anions. 1. Quantum Yields for Generation of Hydrated Electron by 193 and 248 nm Laser Photoexcitation of Miscellaneous Inorganic Anions

Sauer, Myran C.; Crowell, Robert A.; Shkrob, Ilya A.

doi:10.1021/jp049722t

Cited by 123 publications

(159 citation statements)

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“…1 Time dependencies of quantum yield φ t ( ) for the electron in 200 nm photoexcitation of these aqueous anions were obtained as described in section 2 and then fit between 3 ps and 600 ps by a sum of two exponentials with a nonzero offset (Fig. 2).…”

Section: Actinometric Qy Measurements For Various Anions (200 Nm Photmentioning

confidence: 99%

“…Such results per se are of limited import for understanding the photophysics of electron detachment in solution because this yield is a product of two factors: the prompt quantum yield for electron formation and the survival probability Ω ∞ of the resulting geminate pair. 1,4,10 The latter parameter can be determined by time-resolved measurement on a sub-nanosecond time scale. For many aqueous anions, such a measurement requires a pulsed source of ultraviolet (UV) or vacuum UV light, 2 and ultrafast pump-probe studies of these photosystems has only recently become possible.…”

Section: Introductionmentioning

confidence: 99%

“…___________________________________________________________________________________ 1 Work performed under the auspices of the Office of Science, Division of Chemical Science, US-DOE under contract number W-31-109-ENG-38.…”

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confidence: 99%

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Electron Photodetachment from Aqueous Anions. 3. Dynamics of Geminate Pairs Derived from Photoexcitation of Mono- vs Polyatomic Anions

Lian

Oulianov²,

Crowell³

et al. 2006

J. Phys. Chem. A

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Photostimulated electron detachment from aqueous inorganic anions is the simplest example of solvent-mediated electron transfer. As such, this photoreaction became the subject of many ultrafast studies. Most of these studied focussed on the behavior of halide anions, in particular, iodide, that is readily accessible in the UV. In this study, we contrast the behavior of these halide anions with that of small polyatomic anions, such as pseudohalide anions (e.g., HS -) and common polyvalent anions (e.g., kinetics. These analyses suggest that for polyatomic anions (including all polyvalent anions studied) the initial electron distribution has a broad component, even at relatively low photoexcitation energy. There seem to be no well-defined threshold energy below which the broadening of the distribution does not occur, as is the case for halide anions.Direct ionization to the conduction band of water is the most likely photoprocess broadening the electron distribution. The constancy of (near-unity) prompt quantum yields vs. the excitation energy as the latter is scanned across the lowest charge-transferto-solvent band of the anion is observed for halide anions and Fe(CN) 6 4-but not for other anions: the prompt quantum yields are considerably less than unity and depend strongly on the excitation energy. Our study suggests that halide anions are in the class of their own; photodetachment from polyatomic, especially polyvalent, anions follows a different set of rules.

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Section: Actinometric Qy Measurements For Various Anions (200 Nm Photmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electron Photodetachment from Aqueous Anions. 3. Dynamics of Geminate Pairs Derived from Photoexcitation of Mono- vs Polyatomic Anions

Lian

Oulianov²,

Crowell³

et al. 2006

J. Phys. Chem. A

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“…Charge transfer to solvent (CTTS) theoretical and experimental studies have been performed 34 and also applied specifically to ferrocyanide and other charge transfer systems. 31,35 The ionization potentials for Co(III) and Fe(III) atom are reported to be I p = 7.86 eV and I p = 7.87 eV, respectively 36 and the photoelectric threshold has been determined to be~3.2 eV for the hydrated electron in bulk water solution, which also corresponds to the solvation energy of the electron in water. 37 The difference of 4.66 eV between these two values is therefore the minimum energy needed to excite the M(III)(ox) molecule to the CTTS state.…”

Section: Photoelectron Detachment Mechanismmentioning

confidence: 99%

Electron Transfer in Metal‐Organic Molecules. A Time Resolved EXAFS and Optical Spectroscopy Study

Chen

Rentzepis

2011

J Chinese Chemical Soc

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We have measured, by means of ultrafast x-ray absorption and optical spectroscopy, the M-O (M=Fe, Co) and Co-N metal to ligand bond length change as a function of time and the formation and decay of the excited states and intermediate species, after excitation with a 267 nm femtosecond pulse. These experimental data combined with DFT calculations allowed us to determine the mechanism of electron transfer operating in the redox reaction of two metal-ligand complexes, [M(III)(C 2 O 4 ) 3 ] 3-and [Co(III)(NH 3 ) 6 ] 3+ . Based on the data we find that, even though both molecules are excited into their charge transfer band, the redox reaction of [M(III)(C 2 O 4 ) 3 ] 3-proceeds via intermolecular electron transfer while [Co(III)(NH 3 ) 6 ] 3+ electron transfer mechanism is intramolecular.

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“…In a more recent review, 7 the importance of electron transfer as a "critical link" was highlighted for the understanding of many electron photoexcitation processes. More recently, dynamic aspects of the CTTS excitation and electron photodetachment from halide ions, mostly iodide, in water clusters 4,[8][9][10] and in aqueous solution [11][12][13][14] have been extensively investigated with the object of characterizing the solvent restructuring associated with the phenomenon. Although the electronic structure of iodide CTTS excited states and their evolution along the solvent coordinate are well known at present, less information exists about other types of CTTS donors.…”

Section: Introductionmentioning

confidence: 99%

Short-range and long-range solvent effects on charge-transfer-to-solvent transitions of I− and K+I− contact ion pair dissolved in supercritical ammonia

Sciaini

Fernández‐Prini

Estrin

et al. 2007

The Journal of Chemical Physics

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Articles you may be interested inVertical excitation and electron detachment energies associated with the optical absorption of iodide ions dissolved in supercritical ammonia at 420 K have been calculated in two limiting scenarios: as a solvated free I − ion and forming a K + I − contact ion pair ͑CIP͒. The evolution of the transition energies as a result of the gradual building up of the solvation structure was studied for each absorbing species as the solvent's density increased, i.e., changing the NH 3 supercritical thermodynamic state. In both cases, if the solvent density is sufficiently high, photon absorption produces a spatially extended electron charge beyond the volume occupied by the solvated solute core; this excited state resembles a typical charge-transfer-to-solvent ͑CTTS͒ state. A combination of classical molecular dynamics simulations followed by quantum mechanical calculations for the ground, first-excited, and electron-detached electronic states have been carried out for the system consisting of one donor species ͑free I − ion or K + I − CIP͒ surrounded by ammonia molecules. Vertical excitation and electron detachment energies were obtained by averaging 100 randomly chosen microconfigurations along the molecular dynamics trajectory computed for each thermodynamic condition ͑fluid density͒. Short-and long-range contributions of the solventϪdonor interaction upon the CTTS states of I − and K + I − were identified by performing additional electronic structure calculations where only the solvent interaction due to the first neighbor molecules was taken into account. These computations, together with previous experimental evidence that we collected for the system, have been used to analyze the solvent effects on the CTTS transition. In this paper we have established the following: ͑i͒ the CTTS electron of free I − ion or K + I − CIP presents similar features, and it gradually localizes in close proximity of the iodine parent atom when the ammonia density is increased; ͑ii͒ for the free I − ion, the short-range solvent interaction contributes to the stabilization of the ground state more than it does for the CTTS excited state, which is evidenced experimentally as a blueshift in the maximum absorption of the CTTS transition when the density is increased; ͑iii͒ this effect is less noticeable for the K + I − ion pair, because in this case a tight solvation structure, formed by four NH 3 molecules wedged between the ions, appears at very low density and is very little affected by changes in the density; ͑iv͒ the long-range contribution to the solvent stabilization can be neglected for the K + I − CIP, since the main features of its electronic transition can be explained on the basis of the vicinity of the cation; ͑v͒ however, the long-range solvent field contribution is essential for the free I − ion to become an efficient CTTS donor upon photoexcitation, and this establishes a difference in the CTTS behavior of I − in bulk and in clusters.

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Electron Photodetachment from Aqueous Anions. 1. Quantum Yields for Generation of Hydrated Electron by 193 and 248 nm Laser Photoexcitation of Miscellaneous Inorganic Anions

Cited by 123 publications

References 80 publications

Electron Photodetachment from Aqueous Anions. 3. Dynamics of Geminate Pairs Derived from Photoexcitation of Mono- vs Polyatomic Anions

Electron Photodetachment from Aqueous Anions. 3. Dynamics of Geminate Pairs Derived from Photoexcitation of Mono- vs Polyatomic Anions

Electron Transfer in Metal‐Organic Molecules. A Time Resolved EXAFS and Optical Spectroscopy Study

Short-range and long-range solvent effects on charge-transfer-to-solvent transitions of I− and K+I− contact ion pair dissolved in supercritical ammonia

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