Influence of the Habit of Silver Halide Crystals on the Absorption Spectra of Adsorbed Sensitizing Dyes II. Chloride Emulsions

Vanassche, W.; Claes, F.H.; Borginon, H.; Libeer, J.

doi:10.1080/00223638.1973.11737717

Cited by 2 publications

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“…Figure 6 shows the atomic arrangement within a silver halide unit cell and orientation of three important crystallographic surfaces: silver halide cubes are bounded by 100 surfaces, dodecahedra are bounded by 110 surfaces, and octahedra are bounded by 111 surfaces. The arrangement of lattice ions and the associated interlattice site distances (47)(48)(49) on perfect surfaces are exhibited in Figure 7. Newly developed analytical techniques, such as surface extended x-ray absorption fine structure (sexafs) and atomic force microscopy (afm), suggest that the structure and interionic separations on the surface of silver halide microcrystals are the same as in the bulk for 100 AgBr surfaces, but that some reconstruction may occur on 111 surfaces because of electrostatic effects (50,51).…”

Section: Techniques Of Crystal Growthmentioning

confidence: 99%

“…As in chemical sensitization, spectral sensitization is usually done after precipitation but before coating, and usually is achieved by adsorbing certain organic dyes to the silver halide surfaces (47,48,(212)(213)(214)(215)(216)(217)(218)(219)(220)(221)(222)(223)(224)(225)(226)(227)(228)(229). Once the dye molecule is adsorbed to the crystal surface, the effects of electromagnetic radiation absorbed by the dye can be transferred to the crystal.…”

Section: Spectral Sensitizationmentioning

confidence: 99%

“…The resulting longwavelength absorption bands are referred to as J-bands and are characterized by sharp, intense absorption peaks. The extinction and wavelength of maximum absorption for a J-band depend on the refractive index of the substrate (233) and on the crystallographic orientation of the substrate (47,48,234). Adsorbed spectral sensitizing dyes generally produce a photographic sensitivity proportional to the number of photons absorbed.…”

Section: Dipolar Amidic Systemmentioning

confidence: 99%

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Photography

Locker¹

2000

Kirk-Othmer Encyclopedia of Chemical Technology

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PHOTOGRAPHYThe unique light-sensing properties of silver halide crystals have been recognized since the 1500s. In spite of many technical advances in nonsilver halide (eg, electronic) technologies, chemically based silver halide systems continue to dominate in the ability to record images (1-3) of superb image quality and archival characteristics. Photochemical reduction in which the silver ion, Ag + , in the ionic silver halide crystal is reduced to elemental silver, Ag 0 (4-7) was first observed by the alchemist Fabricius in 1556. As photochemical reduction continues, elemental silver atoms aggregate and grow into clusters of a colloidal size sufficient to scatter light and produce hue shifts. The science of photography uses this photochemical property of silver halide to form images and record scenes. One of the earliest researchers to produce such a photochemical image was Schultze in 1727 (8). In these experiments, solutions of silver nitrate and white chalk were photochemically reduced to produce metallic silver images when the solutions were exposed through stencils.The daguerreotype process, prepared by Daguerre in 1837, and the calotype process, produced by Talbot in 1841, were among the first photographic techniques to produce continuous-tone images as reproductions of scenes (9, 10). The steps of a typical daguerreotype process include polishing and cleaning a silver-plated copper plate; treating the silver side of the plate with iodine vapors to convert silver into light-sensitive silver iodide [7783-96-2], AgI; exposing the plate through the optics of a camera that projects and focuses a scene on the plate, ie, where light strikes these plates, silver ions are photochemically reduced to silver metal; and treating the exposed plate with mercury. The mercury reacts with silver metal to produce a silver amalgam.White silver amalgam appears in areas of the plate exposed by light; the unexposed areas remain dark, thereby producing a positive image.Daguerrotype images were produced primarily by the action of light. For the production of satisfactory images, long exposures to light, on the order of minutes, were required because many absorbed photons were necessary to reduce photochemically enough silver ions to silver metal for visible imaging. In 1841, Talbot announced the calotype process, which could reduce exposure times to seconds and produce visible images without dependence on the action of light (11). In the calotype process, the exposure of silver halide produced an invisible latent image that was composed of only trace amounts of reduced silver. This acted as a catalyst for subsequent chemical reduction, ie, a nonphotochemical continuation of the light-initiated reduction process that eventually produced a visible silver image. In addition to being sensitive to much lower light levels, the calotype process was less expensive than the daguerreotype process and provided a negative-positive system that could generate several positive copies from a single negative original. The use of chemical amplif...

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Section: Techniques Of Crystal Growthmentioning

confidence: 99%