| 1. |
- Carlsson, Bo, et al.
(författare)
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Optical Properties of Metallic Copper in Relation to the Photochromic System CuCl(s)-H2O(l)
- 1976
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Ingår i: Journal of Photochemistry. - : Elsevier BV. - 0047-2670. ; 5:4, s. 321-328
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Tidskriftsartikel (refereegranskat)abstract
- An extended Mie theory has been used to interpret the green colour change observed in the photochemical disproportionation of CuCl. Comparison of calculated and experimental spectra leads to the following conclusions: (i) the green colour arises from colloidal metallic copper in CuCl present in low concentrations (<5 vol %); (ii) the colloid consists of particles with an average diameter of about 3 nm in diameter and probably oblate in shape with an axis ratio of about 0.6; (iii) under the conditions of the present experiment the spectrum of the green species stayed constant, i.e. continued exposure has primarily the effect of increasing the number of copper particles without affecting their size and shape.
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| 2. |
- Carlsson, Bo, et al.
(författare)
-
Studies of the Photochromic Properties of the System CuCl(s)-H2O(l) Using Auger Electron Spectroscopy
- 1977
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Ingår i: Journal of Photochemistry. - : Elsevier BV. - 0047-2670. ; 7:1, s. 51-58
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Tidskriftsartikel (refereegranskat)abstract
- The photochromic disproportionation of Cu+ into Cu2+ and Cu0 has been studied in the system CuCl(s)---H2O(l) by obtaining Auger electron spectroscopy measurements of copper in CuCl. The MMM Auger spectrum of CuCl consists mainly of one broad peak with a maximum at an energy 4 eV lower than the two main peaks in the spectrum of metallic copper. In photochromic coloured CuCl only one additional peak appears within the energy range of the peaks of metallic copper, but in the spectrum of CuCl exposed to a concentrated electron beam both metallic copper peaks are visible. This provides experimental evidence that photochemically produced metallic copper clusters in CuCl are extremely small compared with the metallic copper particles formed during electron exposure.
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| 3. |
- Carlsson, Bo, et al.
(författare)
-
The Photochromic Properties of the System CuCl(s)-H2O(l) in Relation to the Composition of the Aqueous Solution
- 1979
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Ingår i: Journal of Photochemistry. - : Elsevier BV. - 0047-2670. ; 11:6, s. 403-412
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Tidskriftsartikel (refereegranskat)abstract
- The photochromic properties of the system CuCl(s)---H2O(l) in relation to the composition of the aqueous solution were studied using diffuse reflectance spectroscopy. The photochemical disproportionation of Cu+ into Cu2+ and Cu0 proved to be essentially independent of pH, ionic strength and the concentrations of Cu2+ and Cl− in the solution. The reverse reaction, i.e. thermal fading, takes place in two steps, one initial exponential step followed by a second step of zero order, i.e. of constant reaction rate. For both steps the reaction rate is independent of the concentration of metallic copper. The rate of the initial step is proportional to the product of the Cu2+ and Cl− concentrations of the solution. The rate of the second step is independent of the Cu2+ concentration and proportional to the Cl− concentration. The results are consistent with the following mechanism for the bleaching reaction: (I) diffusion of Cu2+---Cl− complexes to reaction sites on the surface; (II) fast chemical reaction between Cu2+---Cl− and Cu0 at the reaction sites yielding CuCl; (III) desorption of the product CuCl by complex formation with Cl− ions.
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