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“Determination of the silver sulphide cluster size distribution via computer simulations”. Charlier E, Gijbels R, Van Doorselaer M, De Keyzer R page 85 (2000).
Abstract: Addition of a labile sulphur donor to light sensitive silver halide microcrystals results in the formation of a distribution of silver sulphide clusters on the crystal surface. These silver sulphide clusters enhance the efficiency of image formation during the photographic process. Their activity towards the capturing of light photons, however, is very critical to their size (aggregation number) and concentration. By incorporating gold ions into silver sulphide clusters it was possible to monitor the size distribution by measuring the amount of gold reacted. From these experiments, no evidence was found for aggregation of the reacted sulphur entities on the surface. The uptake of gold ions at different sulphur concentrations could well be fitted with a simulated size distribution when a catalyzed deposition of sulphur was assumed, with a reactivity of the surface equal to 1.0 % for the microcrystals studied. From a simulation of the silver sulphide cluster size distribution a correlation could also be found between increasing aggregation numbers and the absorption at increasing wavelengths in diffuse reflectance spectroscopy.
Keywords: H1 Book chapter; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
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“Functioning of thiocyanate ions during sulphur and sulphur-plus-gold Sensitization”. Charlier E, Gijbels R, Van Doorselaer M, De Keyzer R, , 172 (2000)
Abstract: Not much about the effect of thiocyanate addition on the sulphur ripening is known, although it is used for many applications in photographic practice. Via a combination of tracer analysis and diffuse reflectance spectroscopy the effect of thiocyanate addition on the sulphur and sulphur-plus-gold ripening could be unveiled. When thiocyanate is added prior to the sulphur addition, it appears to rearrange the silver halide surface in such way that the sulphur deposition rate is enhanced, but the supply of interstitials is limited. Addition of thiocyanate after the sulphur reaction results in the formation of thiocyanate complexes with silver, from which a silver ion is more easily deposited in a surface cell of the silver sulphide clusters thus enhancing the sensitization rate. For sulphur-plus-gold sensitized emulsions it was observed that part of the gold ions could be removed out of the Ag2-xAuxS clusters by addition of thiocyanate ions and subsequent washing. Hence, it was concluded that two different types of gold ions are present in the silver sulphide clusters; 1. gold ions which are substitutional for silver (bound between sulphur and bromide ions) 2. gold ions which bridge two or three sulphur atoms. Incorporation of gold ions into silver sulphide clusters suppresses their optical absorption in diffuse reflectance spectroscopy. Since the optical absorption at 505 nm can completely be restored by addition of thiocyanate, it is assumed that the entity absorbing at this wavelength is a monomer of silver sulphide.
Keywords: P1 Proceeding; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
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“The influence of the precipitation method on defect formation in multishell AgBrI (111) tabular crystals”. Van Renterghem W, Karthauser S, Schryvers D, van Landuyt J, De Keyzer R, Van Roost C, , 167 (2000)
Abstract: Multishell tabular grains have a higher speed than pure AgBr tabular grains. Usually the shells differ in size and iodide content, but also the precipitation method for the iodide containing shells has an influence on the iodide incorporation. A TEM investigation was performed to determine the defect structure of multishell AgBr (111) tabular crystals containing a shell with a low iodide concentration and one with a high iodide concentration. The twins that induce tabular growth and stacking fault contrast in the region of the iodide shells have been observed, similar to previously studied AgBr/Ag(Br,I) coreshell crystals. Moreover in some of the crystals dislocations have been observed, sometimes even an entire network. The number of dislocations formed varies for the different methods of iodide addition. Also variations in average thickness between the different iodide addition methods have been observed. A higher number of dislocations and thicker crystals point towards a higher local concentration of iodide. These observations allow deciding which iodide incorporation method is most useful for a preferred dislocation pattern.
Keywords: P1 Proceeding; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
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“Unveiling the composition of sulphur sensitization specks by their interactions with TAI”. Charlier E, van Doorselaer M, Gijbels R, de Keyzer R, Geuens I, Journal Of Imaging Science And Technology 44, 235 (2000)
Abstract: A two-step process for the formation of sensitivity centers different from earlier described two-step processes was found for sulfur sensitized emulsions. After deposition of sulfur in the first step, it was found that the second step does not consist of rearrangement of sulfur over the surface, but of the supply of silver interstitial ions towards the deposited sulfur clusters. The two processes could be separated by adsorbing and desorbing TAI (4-hydroxy-1, 3,3a, 7-tetraazaindene) at/from the silver halide surface. When 1.5 mmol TAI/mol Ag is added before the sulfur reaction, the silver interstitials are immobilized but sulfur still can be deposited at the same level. By lowering the pH to 2.50 after this sulfur reaction, TAI is desorbed from the surface and the released interstitials then cause a restoration of the properties of a sulfur system without TAI. These effects could be demonstrated via diffuse reflectance spectroscopy (DRS), sensitometry and dielectric loss measurements. We could also confirm the isolation of silver sulfide clusters by TAI from other chemicals in the solution, by adsorption of TAI on the clusters.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 0.348
Times cited: 16
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“Influence of twinning on the morphology of AgBr and AgCl microcrystals”. van Renterghem W, Goessens C, Schryvers D, van Landuyt J, Bollen D, de Keyzer R, van Roost C, The journal of imaging science and technology 45, 349 (2001)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 0.348
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“A TEM study of non-parallel twins inducing thickness growth in silver chloride {111} tabular crystals”. van Renterghem W, Schryvers D, van Landuyt J, Bollen D, van Roost C, de Keyzer R, The journal of imaging science and technology 45, 83 (2001)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 0.348
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“The influence of crystal thickness on the image tone”. van Renterghem W, Schryvers D, van Landuyt J, van Roost C, de Keyzer R, Journal of imaging science 47, 133 (2003)
Abstract: It is known that the neutral image tone of a developed photographic film becomes brownish when the thickness of the original silver halide tabular crystals is reduced. We investigate by electron microscopy to what extent the silver filament structure has changed and how it induces the shift in image tone. Therefore, two samples of AgBr {111} tabular crystals with average thicknesses of 160 nm and 90 nm respectively, are compared. It is shown that the dimensions and defect structure of the filaments are comparable, but that the 90 nm crystals result in a more widely spaced structure, which explains the shift in image tone on a qualitative level. The influence of the addition of an image toner, i.e., phenylmercaptotetrazole, on the filament structure is also investigated. An even more open filament structure of longer, but smaller filaments was observed.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 0.348
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