Dye desensitization studies: AgBr core-shell versus AgBr core-AgIBr shell emulsions

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dc.contributor.author Zheng, J. en_US
dc.contributor.author DiFrancesco, A. Gary en_US
dc.contributor.author Hailstone, Richard en_US
dc.contributor.author Callant, Paul en_US
dc.contributor.author DeKeyzer, Rene en_US
dc.date.accessioned 2008-03-10T17:05:32Z
dc.date.available 2008-03-10T17:05:32Z
dc.date.issued 2003 en_US
dc.identifier.citation Imaging Science Journal 51N1 (2003) 47-62 en_US
dc.identifier.issn 1368-2199 en_US
dc.identifier.uri http://hdl.handle.net/1850/5821
dc.description.abstract Four 0.73 μm core-shell octahedral emulsions, sulphur-plus-gold sensitized either internally or on the surface, were used to study dye desensitization by anionic J-aggregating dyes. Two of the emulsions were pure AgBr and two contained AgBr cores with AgI[0.01] Br[0.99] shells. Four dyes having a systematically varying electrochemical oxidation potential, E[ox], were studied at 20, 40, 60, 80 and 100 per cent monolayer coverage. None of the dyes desensitized the internal image of either emulsion. However, desensitization of the surface-sensitized emulsions was observed, particularly for the dyes with E[ox] less than about 1.1 V (versus Ag/AgCl in acetonitrile), and it was greater for the iodobromide surface. Photobleaching studies showed that the dye bleaching rate was greater on the iodobromide surface. Spectral speeds for internal image formation as a function of dye coverage agreed with predicted speeds obtained from integrated absorption spectra for three of the dyes. However, the dye whose lowest unoccupied molecular orbital (LUMO) was the lowest in energy of all four dyes only agreed with the predicted spectral speed at lower dye coverages. Deviation from predicted spectral speed at higher dye coverage for this dye was attributed to the mean of its LUMO energy-level distribution being near the bottom of the conduction band. At low dye coverages formation of J-aggregates near 'special sites' populated the upper levels of this distribution, but additional aggregates formed at higher dye coverages populated the lower levels of the distribution. The higher desensitization for dyes adsorbed to the iodobromide surface suggested that the dye energy levels lie higher in energy on this surface than on the AgBr surface (Refer to PDF for exact formulas). en_US
dc.publisher Maney Publishing on behalf of the Royal Photographic Society en_US
dc.relation.ispartofseries vol. 51 en_US
dc.relation.ispartofseries no. 1 en_US
dc.subject Energy levels en_US
dc.subject Photographic emulsions en_US
dc.subject Silver bromides en_US
dc.subject Silver iodides en_US
dc.subject Spectral sensitization en_US
dc.subject Ternary compounds en_US
dc.title Dye desensitization studies: AgBr core-shell versus AgBr core-AgIBr shell emulsions en_US
dc.type Article en_US

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