Shapes of optical spectra of solvated electrons. Effect of pressure

Jou, Fang‐Yuan; Freeman, Gordon R.

doi:10.1021/j100524a021

Cited by 142 publications

(133 citation statements)

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“…In contrast, they would be compatible with the generation of a phenoxy radical from the phenolic group of BP-4. The same 380-nm transient species was observed at pH 7.5, but no evidence of formation of solvated electrons (absorption maximum at 720 nm; Jou and Freeman, 1977) could be found under any conditions. This issue excludes a photoionisation pathway to produce the phenoxy radical, which would be consistent with the lack of radical formation at pH 10.…”

Section: Direct Photolysissupporting

confidence: 56%

Photochemical processes involving the UV absorber benzophenone-4 (2-hydroxy-4-methoxybenzophenone-5-sulphonic acid) in aqueous solution: Reaction pathways and implications for surface waters

et al. 2013

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processes involving the UV absorber benzophenone-4 (2-hydroxy-4-methoxybenzophenone-5-sulphonic acid) in aqueous solution. Reaction pathways and implications for surface waters. Wat. Res. 2013, 47, 5943-5953. DOI: 10.1016/j.waters.2013 You may download, copy and otherwise use the AAM for non-commercial purposes provided that your license is limited by the following restrictions:(1) You may use this AAM for non-commercial purposes only under the terms of the CC-BY-NC-ND license.(2) The integrity of the work and identification of the author, copyright owner, and publisher must be preserved in any copy. AbstractThe sunlight filter benzophenone-4 (BP-4) is present in surface waters as two prevailing forms, the singly deprotonated (HA − ) and the doubly deprotonated one (A 2− ), with pK a2 = 7.30±0.14 (µ±σ, by dissociation of the phenolic group). In freshwater environments, BP-4 would mainly undergo degradation by reaction with • OH and direct photolysis. The form HA − has a second-order reaction rate constant with • OH ( OH k • ) of (1.87±0.31)⋅10 10 M −1 s −1 and direct photolysis quantum yield Φ equal to (3.2±0.6)⋅10 −5 . The form A 2− has (8.46±0.24)⋅10 9 M −1 s −1 as the reaction rate constant with • OH and (7.0±1.3)⋅10 −5 as the photolysis quantum yield. The direct photolysis of HA − likely proceeds via homolytic breaking of the O-H bond of the phenolic group to give the corresponding phenoxy radical, as suggested by laser flash photolysis experiments. Photochemical modelling shows that because of more efficient direct photolysis (due to both higher sunlight absorption and higher photolysis quantum yield), the A 2− form can be degraded up to 3 times faster than HA − in surface waters. An exception is represented by low-DOC (dissolved organic carbon) conditions, where the • OH reaction dominates degradation and the transformation kinetics of HA − is faster compared to A 2− . The half-life time of BP-4 in mid-latitude summertime would be in the range of days to weeks, depending on the environmental conditions. BP-4 also reacts with Br 2 −• , and a rate constant

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Section: Direct Photolysissupporting

confidence: 56%

Photochemical processes involving the UV absorber benzophenone-4 (2-hydroxy-4-methoxybenzophenone-5-sulphonic acid) in aqueous solution: Reaction pathways and implications for surface waters

et al. 2013

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“…We observe that the spectra of the clusters with IB excess electron state appear slightly blue shifted from the 300 K bulk hydrated electron spectrum (maximum at 1.72 eV experimentally, 42 1.92 eV from simulation 34 ), mainly due to electrostriction. 13 The surface-bound state spectra are, on the other hand, significantly red-shifted, gradually blue shifting with increasing size to larger energy gaps in apparent agreement with experiments.…”

Section: 40mentioning

confidence: 74%

Interior- and surface-bound excess electron states in large water cluster anions

Madarász

Rossky

Túri

2009

The Journal of Chemical Physics

122

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We present the results of mixed quantum/classical simulations on relaxed thermal nanoscale water cluster anions, ( ), with n=200, 500, 1000 and 8000. By using initial equilibration with constraints, we investigate stable/metastable negatively charged water clusters with both surface-bound and interior-bound excess electron states. Characterization of these states is performed in terms of geometrical parameters, energetics, and optical absorption spectroscopy of the clusters. The calculations provide data characterizing these states in the gap between previously published calculations, and experiments, on smaller clusters and the limiting cases of either an excess electron in bulk water, or an excess electron at an infinite water/air interface. The present results are in general agreement with previous simulations and provide a consistent picture of the evolution of the physical properties of water cluster anions with c E-mail: turi@chem.elte.hu, fax: (36)-1-372-2592 madaradam@gmail.com, fax: (36)-1-372-2592 rossky@mail.utexas.edu, fax: (1)-512-471-1624 3 size over the entire size range, including results for vertical detachment energies and absorption spectra that would signify their presence. In particular, the difference in size dependence between surface-bound and interior-bound state absorption spectra is dramatic, while for detachment energies the dependence is qualitatively the same.4 IntroductionThe physics of water cluster anions has remained an important focus of research efforts for more than two decades. The intense scientific interest is largely motivated by the central role of water cluster anions in various important physical processes in atmospheric chemistry, interstellar chemistry, and in electron-initiated processes in aqueous systems. 1 Furthermore, the finite size and the anticipated relative simplicity of water cluster anions, compared to a condensed phase 1 renders them an excellent model for both experimental 2,3,4,5,6,7,8,9,10 and theoretical methods under welldefined conditions. 11,12,13,14 Despite the considerable effort invested, there is still no consensus on the most basic structural properties of water cluster anions. Two distinct localization patterns have been predicted by theory for water cluster anions. In the interior-bound (IB)states, the excess electron localizes in a solvent void surrounded by properly oriented water molecules in clear analogy to the hydrated electron. 11-14, 15,16,17,18,19,20 Theoretical work also suggested that an alternative binding motif may exist with the excess electron being stabilized by the electrostatic reaction field of the cluster dipole, in surface-bound (SB) states, with significant electronic amplitude appearing outside the molecular framework. 11-20Sophisticated experiments on size selected clusters, however, observe at least three characteristic cluster anion classes reflected by three distinctly different trends in the variation of the vertical electron detachment energy with size. 8,9,21 The systematic trends clearly suggest a commonali...

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“…The methods of sample preparation (ll), temperature control, irradiation, and optical measurement (12)(13)(14) were essentially the same as described in the indicated references. In brief, a 0.1 bs pulse of 1.8 MeV electrons delivered 1-2 x 1016 eV/g to the sample.…”

Section: Techniquesmentioning

confidence: 99%

“…Electrons in the shallower traps h2;-a greater probability of reacting per unit time than do those in deeper traps. We therefore choose as an indicator of the trap depth for kinetics purposes the quantity E, = (E,,,, -W,), where E,,,, is the energy at absorption maximum and W, is the portion of the width at half height that is on the red side of E,,,, (13,26). E, is therefore the energy half way up the red side of the band.…”

Section: -Propanol (A) Tert-butyl Alcohol (I]) and Ethylene Glycolmentioning

confidence: 99%

The reactivity of allyl and propargyl alcohols with solvated electrons: temperature and solvent effects

Afanassiev¹,

Okazaki²,

Freeman³

1979

Can. J. Chem.

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. Can. J. Chem. 57,839 (1979).The rate constants kl for the reaction of solvated electrons with allyl alcohol in a number of hydroxylic solvents differ by up to two orders of magnitude and decrease in the order tertbutyl alcohol > 2-propanol > 1-propanol a ethanol > methanol a ethyleneglycol > water.In methanol and ethylene glycol the rate constants (7 x lo7 M-' s-' at 298 K) and activation energies (16 kJ/mol) are equal, in spite of a 32-fold difference in solvent viscosity (0.54 and 17.3 cP, respectively) and 3-fold difference in its activation energy (11 and 32 kJ/mol, respectively). The reaction in tert-butyl alcohol is nearly diffusion controlled and has a high activation energy that is characteristic of transport in that liquid (El = 31 kJ/mol, En = 39 kJ/mol). The activation energies in the other alcohols are all 16 kJ/mol, and it is 14 kJ/mol in water. They do not correlate with transport properties. The solvent effect is connected primarily with the entropy of activation. The rate constants correlate with the solvated electron trap depth. When the electron affinity of the scavenger is small, a favorable configuration of solvent molecules about the electronlscavenger encounter pair is required for the electron jump to take place. The behavior of the rate parameters for propargyl alcohol is similar to that for allyl alcohol, but kl, A', and El are larger for the former. The ratio k(propargyl)/k(allyl) at 298 K equals 10.5 in water and decreases through the series, reaching 1.3 in tert-butyl alcohol. Rate parameters for several other scavengers are also reported. Dans tous les autres alcools, les Cnergies d'activation sont toutes Bgales ti 16 kJ/mol; dans I'eau E, est Cgale a 14 kJ/mol. Ces valeurs ne peuvent pas Ctre reliks avec les propriCtes de transport. L'effet de solvant est principalement liC a I'entropie d'activation. I1 y a un corrtlation entre les constantes de vitesse et les profondeurs des pitges des Clectron solvatBs. Lorsque I'affinitC Clectronique pour le solutC est faible, il faut une configuration favorable des molBcules de solvant autour de la paire Clectron-solutC qui se rencontre pour que le saut Blectronique puisse s'effecteur. Le comportement des parametres de vitesse pour I'alcool propargylique est semblable a celui de I'alcool allylique; les valeurs de kl, Al et El sont toutefois plus ClevCes

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Shapes of optical spectra of solvated electrons. Effect of pressure

Cited by 142 publications

References 5 publications

Photochemical processes involving the UV absorber benzophenone-4 (2-hydroxy-4-methoxybenzophenone-5-sulphonic acid) in aqueous solution: Reaction pathways and implications for surface waters

Photochemical processes involving the UV absorber benzophenone-4 (2-hydroxy-4-methoxybenzophenone-5-sulphonic acid) in aqueous solution: Reaction pathways and implications for surface waters

Interior- and surface-bound excess electron states in large water cluster anions

The reactivity of allyl and propargyl alcohols with solvated electrons: temperature and solvent effects

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