Quantum yields of hydrated electrons by UV laser irradiation

Iwata, Akyhiro; Nakashima, Nobuaki; Kusaba, Mitsuhiro; Izawa, Yasukazu; Yamanaka, Chiyoe

doi:10.1016/0009-2614(93)87004-m

Cited by 46 publications

(53 citation statements)

References 18 publications

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“…Furthermore, we have estimated the molar absorptivity of several photoproducts at these wavelengths; those estimates are given in Table 3. Our results for 193 nm photolysis of halide and pseudohalide anions correspond well with the previous estimates by Iwata et al [24] and Dainton and Fowles, [29] and we suggest using these photosystems as convenient short-wave actinometric standards for aqueous photochemistry. We also confirm the previous measurements of the quantum yields of water ionization (193 nm one photon excitation) [37] and hydrogen peroxide dissociation (248 nm photoexcitation); [38,45] the latter photosystem also provides a convenient actinometric standard for time-resolved studies.…”

Section: Discussionsupporting

confidence: 91%

“…We also give one-photon quantum yields for ionization of neat water by 193 nm light and dissociation of aqueous hydrogen peroxide by 248 nm light. In the course of this study, we realized that the QY data obtained by Iwata et al [24] were compromised due to the absorption of the laser light by photoproducts generated within the duration of the laser pulse; our analysis includes corrections for this complicating effect. The correction is largest for anions that are efficient electron donors but absorb the excitation light poorly (e.g., SO 3 2-at 248 nm; Table 2) and anions that yield products that strongly absorb at the excitation wavelength (e.g., ferricyanide at 193 nm; Table 2).…”

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confidence: 99%

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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

2004

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Time resolved transient absorption spectroscopy has been used to determine quantum yields for electron photodetachment in 193 nm and (where possible) 248 nm laser excitation of miscellaneous aqueous anions, including hexacyanoferrate(II), sulfate, halide anions (Cl -, Br -, and I -), pseudohalide anions (OH -, HS -, CNS -), and several common inorganic anions for which no quantum yields have been reported heretofore:SO 3 2-, NO 2 -, NO 3 -, ClO 3 -and ClO 4 -. Molar extinction coefficients for these anions and photoproducts of electron detachment from these anions at the excitation wavelengths were also determined. These results are discussed in the context of recent ultrafast kinetic studies and compared with the previous data obtained by product analyses. We suggest using electron photodetachment from the aqueous halide and pseudohalide anions as actinometric standard for time-resolved studies of aqueous photosystems in the UV.

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Section: Discussionsupporting

confidence: 91%

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confidence: 99%

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

2004

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“…It is known that SCN À photolysis can lead to the formation of SCN radicals which will further react to (SCN) 2 À radicals (R4). [70,71] However, the measured quantum yield at l = 248 nm for reaction R6 (F < 0.02) is small. [70][71][72] …”

Section: Kineticsmentioning

confidence: 88%

Tropospheric Aqueous‐Phase Free‐Radical Chemistry: Radical Sources, Spectra, Reaction Kinetics and Prediction Tools

et al. 2010

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The most important radicals which need to be considered for the description of chemical conversion processes in tropospheric aqueous systems are the hydroxyl radical (OH), the nitrate radical (NO(3)) and sulphur-containing radicals such as the sulphate radical (SO(4)(-)). For each of the three radicals their generation and their properties are discussed first in the corresponding sections. The main focus herein is to summarize newly published aqueous-phase kinetic data on OH, NO(3) and SO(4)(-) radical reactions relevant for the description of multiphase tropospheric chemistry. The data compilation builds up on earlier datasets published in the literature. Since the last review in 2003 (H. Herrmann, Chem. Rev. 2003, 103, 4691-4716) more than hundred new rate constants are available from literature. In case of larger discrepancies between novel and already published rate constants the available kinetic data for these reactions are discussed and recommendations are provided when possible. As many OH kinetic data are obtained by means of the thiocyanate (SCN(-)) system in competition kinetic measurements of OH radical reactions this system is reviewed in a subchapter of this review. Available rate constants for the reaction sequence following the reaction of OH+SCN(-) are summarized. Newly published data since 2003 have been considered and averaged rate constants are calculated. Applying competition kinetics measurements usually the formation of the radical anion (SCN)(2)(-) is monitored directly by absorption measurements. Within this subchapter available absorption spectra of the (SCN)(2)(-) radical anion from the last five decades are presented. Based on these spectra an averaged (SCN)(2)(-) spectrum was calculated. In the last years different estimation methods for aqueous phase kinetic data of radical reactions have been developed and published. Such methods are often essential to estimate kinetic data which are not accessible from the literature. Approaches for rate constant prediction include empirical correlations as well as structure activity relationships (SAR) either with or without the usage of quantum chemical descriptors. Recently published estimation methods for OH, NO(3) and SO(4)(-) radical reactions in aqueous solution are finally summarized, compared and discussed.

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“…Previously, such yields had been estimated for two halide anions only, I -and Br -, and were found to be unity across their lower energy CTTS subband. 4,12 In this work, we present a larger pattern of these QYs. Our results suggest that polyatomic anions generally have QYs substantially lower than unity.…”

Section: Introductionmentioning

confidence: 97%

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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Quantum yields of hydrated electrons by UV laser irradiation

Cited by 46 publications

References 18 publications

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

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

Tropospheric Aqueous‐Phase Free‐Radical Chemistry: Radical Sources, Spectra, Reaction Kinetics and Prediction Tools

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

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