Sensitizer Centres: Formation, Properties, Function and Efficiency

Spencer, H. E.; Atwell, R. E.; Lévy, M.

doi:10.1080/00223638.1983.11738236

Cited by 7 publications

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“…35,36 Spencer et al showed that selenium-sensitized emulsions exhibited higher sensitivity than sulphur-sensitized ones, although the former gave higher fog density than the latter. 41 Hailstone et al observed similar results. 42 Morimura et al studied the reactions for the formation of sulphur, selenium and tellurium sensitization centres, and observed that HIRF, which was significant in a sulphur-sensitized AgBr emulsion, was weak in a selenium-sensitized emulsion, and absent in a tellurium-sensitized emulsion.…”

Section: Mechanismmentioning

confidence: 71%

Review of mechanisms of photographic sensitivity

Tani¹

2007

The Imaging Science Journal

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A review is given of studies on the mechanisms of the main processes in photographic sensitivity. They include the formation of latent image centres, chemical sensitization and stabilization, and spectral sensitization. It is noted that remarkable progress in understanding the mechanisms of main photographic processes has been achieved owing to significant efforts by many groups of investigators, who have contributed to the design of highly sensitive and fine silver halide photographic materials.

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Section: Mechanismmentioning

confidence: 71%

Review of mechanisms of photographic sensitivity

Tani¹

2007

The Imaging Science Journal

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“…Previous studies of sulfur sensitization are numerous. − Many of these studies were not directed toward an understanding of the structure and functioning of sulfur-containing centers. Many studies employ S 2 O 3 2- as a sulfur source and are confounded by an activation energy for surface adsorption and an activation energy for decomposition that are similar .…”

Section: Introductionmentioning

confidence: 99%

Photophysics of Sulfur-Containing Centers on AgBr Surfaces

Marchetti¹,

Lushington²,

Baetzold³

2002

J. Phys. Chem. B

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Silver halide microcrystals, the basic element in photographic products, are commonly reacted with labile sulfur-containing compounds to increase their photographic efficiency (speed). Such "sulfur-sensitized" AgBr microcrystals have been examined with computational and photophysical techniques. Density functional and lattice-relaxation computations have given estimates of the optical transition energies and the electron-and hole-trapping abilities of a number of small sulfur-containing clusters that may be deposited on, or buried in, an AgBr surface. These data indicate that single sulfides, whatever their structure, are not deep traps for electrons or holes. Disulfides, in general, can trap holes and certain structures; for example, a disulfide at a double-kink site can trap electrons. Computations indicate that single sulfides substituted for a halogen in the (001) surface and charge compensated with an interstitial silver ion in the surface or in the bulk do not trap electrons; neither do disulfides in the bulk. A single sulfide substituted for a bromide at a positive kink and compensated with an interstitial silver ion appears to be capable of initiating the formation of small, stable silver clusters (Ag n , n ≈ 4) that become "latent image", the centers that eventually lead to a visible photographic image. Photographic data from sulfur-sensitized AgBr microcrystals indicate that the optimum formal sulfur level is about 10 000 S atoms/µm 2 . Radio-frequency photoconductivity measurements show that deposited sulfur centers trap photoelectrons. The optimum and higher levels of sulfur deposited on the surface of AgBr microcrystals produce an absorption band (∼525 nm) and associated low-temperature luminescence (∼725 nm). The luminescence lifetime behavior and ODMR data clearly indicate that this sulfur-related absorption and emission is due to a donor-acceptor processes. ODMR spectra obtained by monitoring the intrinsic AgBr luminescence (590 nm) have a resonance that is assigned to a Ag 2 + center. This Ag 2 + species is thought to arise from a silver dimer associated with a sulfur species at the surface.

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Silver Halide Detector Technology

Hailstone¹

2002

Encyclopedia of Imaging Science and Technology

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This article describes the basic construction and operation of silver halide materials as image recording devices. The detector consists of silver halide microscrystals coated in a gelatin–water mixture on either a transparent or paper support. Strictly speaking the resulting suspension of silver halide microcrystals in aqueous gelatin is classified as a dispersion but early on in the development of photography it was called an “emulsion.” Emulsion is used in this article. A latent image is formed via a photochemical change of the microcrystal. The visible image is created through an image processing step in which those microcrystals that have received sufficient light “blacken” as they are transformed from silver halide to metallic silver. The microcrystals, also called “grains,” are prepared in a variety of shapes and size distributions to accommodate a variety of applications. Over the range of applications, the microcrystal size varies from a few tenths of a micron diameter to several microns diameter. Sensitivity, or speed, increases with increasing grain size, so higher speed films must necessarily use larger grains. Materials intended for image capture need to produce a distinguishable output over a wide range of inputs arid so a polydisperse size distribution is used. On the other hand, materials for image display, such as prints, need to respond only over a relatively narrow range of inputs so a monodisperse size distribution is often used.

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Sensitizer Centres: Formation, Properties, Function and Efficiency

Cited by 7 publications

References 0 publications

Review of mechanisms of photographic sensitivity

Review of mechanisms of photographic sensitivity

Photophysics of Sulfur-Containing Centers on AgBr Surfaces

Silver Halide Detector Technology

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