Ionische Reaktionen bei der γ-Radiolyse ätherischer D
 2
 S-Lösungen

Pukies, J.; Henglein, A.; Meissner, G.

doi:10.1524/zpch.1968.57.3_6.177

Cited by 11 publications

(20 citation statements)

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“…The decay of e,,-and the growth of Ago were followed at 715 and 360 nnl, respectively, in an aqueous solution of lop4 M AgC104 and 0.1 M tell-BuOH at early times following a 20 ns pulse. We found kl = 3.6 X 101OM-'s-', in agreement with earlier work (9). The growth of Ago was equated to the decay of e,,-with small corrections made for the loss of Ago via Ago + Ag+ -Agz+ (9, 10) the decay of e,,-by reactions other than [l] and the absorption at 360 nm due to e,,-.…”

Section: (4) Effect Of' Electron Scavengers At 76 K (A) On the Yieldssupporting

confidence: 90%

“…This new band did not grow after the pulse. We assign it to Ago because of its similarity to the band (A,,,, = 360 nm) attributed to Ago formed in aqueous solutions by the reaction (9,10) This reaction provides an opportunity for estimating the extinction coefficient of the infraredabsorbing electron by comparing the decrease in electron absorption to the increase in the 370 nrn band. However, we could not find a value for €(Ago) in the literature, and so measured it ourselves in the following manner.…”

Section: (4) Effect Of' Electron Scavengers At 76 K (A) On the Yieldsmentioning

confidence: 99%

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Evidence for a second kind of trapped electron in some deuterated aqueous glasses at low temperatures. A pulse radiolysis study

Buxton¹,

Gillis²,

Klassen³

1976

Can. J. Chem.

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. Can. J. Chem. 54, 367 (1976).Several deuterated aqueous glasses have been pulse-irradiated at 76 K. In addition to the well known visible absorption band of e,-, a second intense infrared absorption band, with A,,, > 3200 nm, has been found in ( a ) 50% by volume ethylene glycol, ( b ) 9.5 M LiC1, and ( c ) 2.5 and 4 M MgClz glasses. Electron scavengers decrease the intensities of both bands, but to different extents. An increase in temperature decreases the intensity of the infrared band, but not that of the visible band. These and other features lead us to conclude that the infrared band is due to shallowly trapped electrons which are distinctly different from trapped electrons which absorb in the visible region.The decay of the infrared band extends over several orders of magnitude in time and, unlike that of the visible band, is independent of wavelength. In the two chloride glasses the decay of the infrared band is accompanied by emission (A,,, = 410 nm) and is probably due to a spur reaction between an electron and hydroxyl radical t o form excited hydroxide ion. No emission is found in the ethylene glycol glass, but growth of the visible band matches the decay of the infrared band in this case.By comparing the amount of Ago produced in an ethylene glycol glass containing Ag+ with the decrease in intensity of the infrared and visible bands, we obtain '1400 = (5.7 + 0.8) X lo3 M-1 cm-I. From the shape of the infrared band, which is Lorentzian on the high energy side, we estimate A, , ,

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Section: (4) Effect Of' Electron Scavengers At 76 K (A) On the Yieldssupporting

confidence: 90%

Section: (4) Effect Of' Electron Scavengers At 76 K (A) On the Yieldsmentioning

confidence: 99%

Evidence for a second kind of trapped electron in some deuterated aqueous glasses at low temperatures. A pulse radiolysis study

Buxton¹,

Gillis²,

Klassen³

1976

Can. J. Chem.

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“…4 The Ag 0 atom formed in reaction 1 is very short-lived in the presence of Ag + ions, since it reacts according to Free Ag 2 + absorbs only at 310 nm. 6,4 The absorption band 440 nm in Figure 1 is attributed to the interaction of the Ag 2 + with polyacrylate.…”

Section: Methodsmentioning

confidence: 99%

Time-Resolved Investigation of Early Processes in the Reduction of Ag⁺on Polyacrylate in Aqueous Solution

Ершов

Henglein

1998

J. Phys. Chem. B

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Aqueous solutions of AgClO 4 (4 × 10 -4 to 10 -2 M) and sodium polyacrylate (0.1 M, mean chain length of 30) are exposed to a pulse of high-energy radiation, and the changes in optical absorption are recorded in the time range from microseconds to seconds. The reduction of Ag + by the hydrated electron is slowed by the polyanion, whereas the subsequent reaction of Ag 0 with Ag + is practically not affected. Polymer-bound Ag 2 + has two absorption bands (310 and 440 nm). The formation of Ag 3 2+ in the reaction of Ag 2 + with Ag + is strongly retarded by the polyanion; it occurs in an interchain process at low Ag + concentrations and probably also as an intrachain process at higher ones. Polymer-bound Ag 3 2+ has a broad UV absorption tailing into the visible. At longer times after the pulse (up to seconds), bimolecular interchain processes take place in which colored complexes are formed, which at first contain a small number of silver atoms and an approximately equal number of Ag + ions, and are stabilized by the polyanion chains. IntroductionIn the preceding paper, 1 the early steps of the γ-radiolytic reduction of silver ions in aqueous polyacrylate solution were investigated. The Ag + ions are strongly adsorbed on the polymer chains when polyacrylate is present in substantial excess. The reduction occurs through the hydrated electrons that are formed in the radiolysis of the aqueous solvent. Silver atoms are formed, which then are complexed by Ag + ions, and subsequently, oligomeric clusters appear through coalescence processes. The affinity of some clusters to the polymer is so great that they form stable complexes with polyacrylate of practically infinite lifetime. These complexes are colored rose, green, or blue depending on the size of the clusters. They can be observed spectrophotometrically in the early stages of silver ion reduction, i.e., when less than about 30% of the Ag + ions are reduced. At higher degrees of reduction, the complexes, which are composed of roughly an equal number of silver atoms and ions, are further reduced, and larger clusters and finally metallic nanoparticles consisting of thousands of atoms are present.In the present paper, pulse radiolysis is used to study timeresolved the very early steps that lead to the colored complexes. A solution of AgClO 4 and sodium polyacrylate is exposed to a short pulse of high-energy radiation, and the changes in absorption are recorded after the pulse in the 10 -7 s to seconds range. Only a small fraction of the silver ions is reduced during the pulse. A similar study has previously been made by other authors. 2 The results obtained in the present study are different, since those authors missed some very early events. This difference is probably due to the fact that they used silver sulfate as the silver source; the sulfate ion strongly complexes silver clusters and thus accelerates their coalescence. 3 Pulse radiolysis has previously been used to study the atomto-metal transition of silver in the absence of a stabilizing

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“…In this method, use of moderately high concentrations of Ag + and 4-CBSA (∼40 mM each) are recommended [6,7]. In this context of chemical reduction of μM-mM [Ag + ] in solution, from our recent studies dealing with free radical induced reactions in alcohol medium [9,10] as well as from other similar aqueous medium data available in the literature [11][12][13][14][15][16][17][18][19][20], it has now been established that an yellow-orange silver nanoparticle is obtained therein as the stable reduced product. Therefore, two very dissimilar sets of chemical processes dealing with reduction of Ag + appear to be related to each other.…”

Section: Introductionmentioning

confidence: 99%

Wet Chemical Colorimetric Estimation of CO: An Update on the Reduced Silver Sol Spectral and Kinetic Transformations to Silver nanoparticle

2006

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Measurements of ppm (v/v) level CO g concentration is conveniently performed by its preconcentration in alkaline absorber solution of Ag + -(4)-HCO 2 -C 6 H 4 -SO 2 NH 2 complex, followed by a spectral measurement of the reduced silver sol. In this study, the transitory nature of this latter species and its subsequent real-time transformation to silver nanoparticle are presented. These results were based on spectral measurements made under varying concentrations of alkali, (4)-HCO 2 -C 6 H 4 -SO 2 NH 2 , and Ag + in the absorber solution, and in the presence of a wide range of sampled CO g concentration. The initially created light yellow colored sol with its broad absorption profile peaking at 380 nm and absorption coefficient 3500± 300 cm −1 M −1 (related to the amount of sampled [CO g ] as standardized by gas chromatographic analysis) changed into the characteristic yellow orange nanoparticle with its plasmon band peak absorption at 425 nm and absorption coefficient 6350 ± 300 cm −1 M −1 . Under different sampling conditions, the respective first-order conversion rates varied between 0.03 and 0.15 h −1 , whereas simultaneous dynamic light scattering measurements revealed steady growth of the averaged particle size ranging from 60 to 300 nm.

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Ionische Reaktionen bei der γ-Radiolyse ätherischer D ₂ S-Lösungen

Cited by 11 publications

References 0 publications

Evidence for a second kind of trapped electron in some deuterated aqueous glasses at low temperatures. A pulse radiolysis study

Evidence for a second kind of trapped electron in some deuterated aqueous glasses at low temperatures. A pulse radiolysis study

Time-Resolved Investigation of Early Processes in the Reduction of Ag⁺on Polyacrylate in Aqueous Solution

Wet Chemical Colorimetric Estimation of CO: An Update on the Reduced Silver Sol Spectral and Kinetic Transformations to Silver nanoparticle

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Ionische Reaktionen bei der γ-Radiolyse ätherischer D 2 S-Lösungen

Cited by 11 publications

References 0 publications

Evidence for a second kind of trapped electron in some deuterated aqueous glasses at low temperatures. A pulse radiolysis study

Evidence for a second kind of trapped electron in some deuterated aqueous glasses at low temperatures. A pulse radiolysis study

Time-Resolved Investigation of Early Processes in the Reduction of Ag+on Polyacrylate in Aqueous Solution

Wet Chemical Colorimetric Estimation of CO: An Update on the Reduced Silver Sol Spectral and Kinetic Transformations to Silver nanoparticle

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Product

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Ionische Reaktionen bei der γ-Radiolyse ätherischer D ₂ S-Lösungen

Time-Resolved Investigation of Early Processes in the Reduction of Ag⁺on Polyacrylate in Aqueous Solution