Emulsion Grains Research Articles

A Study of Effects of Sulfur Sensitization and a Cyanine Dye upon Physical Properties of Cubic Silver Bromide Emulsion Grains

A Study of Effects of Sulfur Sensitization and a Cyanine Dye upon Physical Properties of Cubic Silver Bromide Emulsion Grains

The Photoexcited State of Silver Halide Photographic Emulsion Grains

The Photoexcited State of Silver Halide Photographic Emulsion Grains

The influence of solution pAg on the transient photoconductivity behaviour of AgBr(100) and AgBr(111) emulsion grains

The transient photoconductivity (TPC) of AgBr emulsion grains is strongly affected by the solution pAg. Both the signal height and the response time increase sharply due to the steep decrease with the pAg of the number of efficient electron traps at the surface. This increase of the signal height and response time against pAg is steeper for AgBr(100) than for AgBr(111). Evidence is given that the number of efficient electron traps varies more steeply with the pAg for cubic than for octahedral grains.

Microwave Photoconductivity of Silver Halide Emulsion Grains

Microwave Photoconductivity of Silver Halide Emulsion Grains

The Limit of Sensitivity of Silver Halide Systems in View of Emulsion Grains

The Limit of Sensitivity of Silver Halide Systems in View of Emulsion Grains

Mechanisms of Pressure Sensitivity Effects in a Model Halide Exchange Emulsion

The response to pre- and post-exposure pressure of a model halide exchange emulsion with a highly disordered grain structure is described. Variations in the response to pressure with changes in surface chemical sensitization and exposure time have been investigated for both surface and internal development. It is shown that the results cannot be interpreted entirely in terms of the classical surface/internal competition mechanism. It is proposed that account must be taken of the effects of pressure on silver halide emulsion grains in terms of the generation of free holes and electrons.

The Influence of the Solution pAg on the Interstitial Concentration of Silver Halides. A Semi-Quantitative Treatment

The concentration of silver interstitials in silver halide microcrystals generally increases with the pAg in the solution before coating. This is not in agreement with the expectations and with conductivity results on large single crystals. The large surface to volume ratio of emulsion grains is suggested to be responsible for this conductivity behaviour. The surface can accommodate enough charge to compensate the excess space charges in the solution and the solid.

Theoretical studies of the effects of grain noise on photographic stellar astrometry and photometry

A method of incorporating the effects of photographic emulsion grain noise into digital image centering algorithms is presented which improves the accuracy of the derived stellar positions and magnitudes. Theoretical formulae are then derived for the limiting error of the center, and the photometric parameters. For IIIa-J, this error is 0.2-0.3 mu for bright unsaturated images, which agrees quite well with measurements made with the Yale PDS microdensitometer. It is expected that, with further improvements in the positional accuracy of the PDS, it should be possible to reach the emulsion grain noise limit, providing that emulsion shifts or other large scale errors do not dominate. It is also shown that, with appropriate trimming, marginal distribution image centering algorithms can yield an accuracy only slightly poorer than that obtained with two-dimensional distributions.

The influence of Triazaindolisine on the microwave photoconductivity of AgBr emulsion grains

physica status solidi (a)Volume 78, Issue 1 p. K47-K52 Short Note The influence of Triazaindolisine on the microwave photoconductivity of AgBr emulsion grains F. Callens, F. Callens Laboratorium voor Kristallografie en Studie van de Vaste Stof, Rijksuniversiteit Gent Search for more papers by this authorW. Maenhout-van der Vorst, W. Maenhout-van der Vorst Laboratorium voor Kristallografie en Studie van de Vaste Stof, Rijksuniversiteit Gent Search for more papers by this author F. Callens, F. Callens Laboratorium voor Kristallografie en Studie van de Vaste Stof, Rijksuniversiteit Gent Search for more papers by this authorW. Maenhout-van der Vorst, W. Maenhout-van der Vorst Laboratorium voor Kristallografie en Studie van de Vaste Stof, Rijksuniversiteit Gent Search for more papers by this author First published: 16 July 1983 https://doi.org/10.1002/pssa.2210780153Citations: 2 Krijgslaan, 281, B-9000 Gent, Belgium. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume78, Issue116 July 1983Pages K47-K52 RelatedInformation

The Concentration Process in the Formation of Development Centres in Silver Halide Microcrystals*

AbstractThis paper discusses the processes whereby silver atoms are concentrated at a few sites during exposure to form development centres in silver halide emulsion grains. Two models are used. With lhe first model, lhe chemically sensitized grain has small surface monolayer islands of AgsS molecules with Ag2 molecules adsorbed al vacant sites around their edges. Exposure results in the photu-oxidation of these Ag2 molecules with liberation of conduction electrons and charge-compensating interstitial silvcr ions. There are many shallow traps in the grains with depths less 1han 5 kT al room temperature which do not altract and trap electrons. If the electron were trapped, the free energy would be increased by the trapping process on account of the enormous density of stales in the conduction band. An effective trap or concentration speck with a depth greater than 16 kT is first formed during exposure by the c(llnbination of an interstitial silver ion and an electron at an Ag2 molecule. followed by lhe ads...

Absorption of Light in Emulsion Grains-Application of Mie Theory

AbstractThe increased absorption in an isolated spherical emulsion grain, relative to that in an equal volume within the bulk absorber, is calculated from Mie theory for sizes, wavelengths and silver halide compositions relevant to photographic emulsions. The factorial increase referred to here as the “raindrop factor” has a maximum value of about 2.2 for intermediate sizes.

A Computer Simulation of Latent Image Formation in Photographic Emulsion by a Monte Carlo Method

A digital computer analysis has been made of photon absorption, chemical sensitization and latent image distribution in a silver halide photographic emulsion, using the Bayer Hamilton model but with a different approach in treating the positive holes.In discussing the effect of sulphur sensitization it has been assumed that silver sulphide molecules can play a dual role in latent image formation, undergoing partial thermal dissociation to increase both the number of electron traps by providing more interstitial silver ions and that of positive hole traps by forming AgS-. The increased interstitial silver ion concentration has also been supposed to lead to an increase in the stability of single silver atoms. As to gold sensitization, it has been assumed that the main effect of gold is to enhance the developahility of latent image centres.Parameter values for simulation under various conditions of chemical sensitization have been calculated, based upon the above assumptions. The results have, as expected, reproduced in many respects those shown by experiments. Finally, a relation between the concentration of interstitial silver ions and the sulphur content in the emulsion grain has been derived.

Effects of Deformation on the Properties of Emulsion Grains

AbstractEmulsion grains have been deformed by bending an emulsion layer coated on film, and the effects of deformation on the dispersity ol photolytic silver and on the number and distribution of development centres have been studied. The observations show thai a major effect of such treatment is to increase the number of sues within a grain at which silver specks can be nucleated.The usual sensitomelric effect of such changes is to increase sensitivity on internal-image development at the expense of sensitivity on surface-image or conventional development. However, it is shown that surface desensitizalion may be accompanied sometimes by internal desensitization rather than sensitization. The internal desensitization can be attributed to competition between the increased number of internal sensitivity centres. Support for this view was obtained from the fact that changes in the effect of deformation on storage prior to exposure (decrease of surface desensitization. decrease of internal sensitization or de...

The influence of EDTA on the space charge characteristics of AgBr and β-AgI emulsion grains

physica status solidi (a)Volume 71, Issue 2 p. K161-K163 Short Note The influence of EDTA on the space charge characteristics of AgBr and β-AgI emulsion grains F. Callens, F. Callens Laboratorium voor Kristallografie en Studie van de Vaste Stof, Rijksuniversiteit Gent Search for more papers by this authorW. Maenhout van der Vorst, W. Maenhout van der Vorst Laboratorium voor Kristallografie en Studie van de Vaste Stof, Rijksuniversiteit Gent Search for more papers by this author F. Callens, F. Callens Laboratorium voor Kristallografie en Studie van de Vaste Stof, Rijksuniversiteit Gent Search for more papers by this authorW. Maenhout van der Vorst, W. Maenhout van der Vorst Laboratorium voor Kristallografie en Studie van de Vaste Stof, Rijksuniversiteit Gent Search for more papers by this author First published: 16 June 1982 https://doi.org/10.1002/pssa.2210710252 Krijgslaan 2 71, B-9000 Gent, Belgium. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume71, Issue216 June 1982Pages K161-K163 RelatedInformation

A size effect on the mobility of slow electrons in microcrystalline AgBr

Measurements of galvanomagnetic effects on AgBr microcrystals dispersed in insulating gelatin layers (photographic emulsion grains) were performed at 4.2–40 K as a function of the grain size (50 nm–1.3 μm) using a fast pulse technique with blocking electrodes. The value of the mobility of slow electrons was determined to be about 103 cm2/V s for 400-nm cubic crystals at 4.2 K, much smaller than that in pure bulk crystals, and decreases with decreasing size of the microcrystals. Additional results obtained from various specimens eliminate the possibility that this size effect is due to differences of impurity concentration. Possible mechanisms of this size effect on the mobility of slow electrons are discussed from the point of view of surface effects.

The effect of the solution pAg and pH on the space charge characteristics of silver bromide emulsion grains

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Studies of Ionic Conduction and Space Charge Layer in Silver Halide Photographic Emulsion Grains

Studies of Ionic Conduction and Space Charge Layer in Silver Halide Photographic Emulsion Grains

Sensitization by Photographic Stabilizers as Related to their Influence upon Ionic Conductivity of Silver Bromide Emulsion Grains

AbstractThe interaction of photographic stabilizers with the surface of silver bromide grains was studied to clarify the mechanism of sensitization caused by the stabilizers. The dielectric loss and Dember effect methods were applied to the measurement of the ioni conductivity of cubic silver bromide emulsions to which photographic stabilizers and their related compounds were added. The compounds with adsorptivity to silver bromide grains decreased the ionic conductivity of the emulsion grains, and increased the photographic sensitivity of the emulsions. It is considered that sensitization by the stabilizers arises from the interaction of their anions with silver ions at kink sites, which results in a decrea e in the concentration of interstitial silver ions.

Factors Influencing Light-Induced ESR Spectra of Dyes Adsorbed by AgBr Emulsion Grains

AbstractLight-induced ESR signals were observed for sensitizing dyes on octahedral and cubic AgBr emulsion grains. The intensity and decay time of the signals increased with the increase in the height of the eho of the dyes. The correlations of the signal intensities with various emulsion factors, such as crystal shape, halide composition, sulphur and reduction sensitizations, halogen acceptors and evacuation, and with the desensitization caused by dyes have been also examined. The dependence of the behaviour of the signals upon the crystal shape has indicated that the height of the eho of a dye is higher by about 0.1 eV on the octahedral grains than on the cubic grains with respect to the top of the valence band of silver bromide. The results obtained in this paper support the view that the dye positive holes are responsible for the ESR signals and for the desensitization.

Etching and Recrystallization Effects of Solutions used in Studies of Latent-image Distribution

Electron micrography has been used to record the etching and recrystallization effects on grains by solutions used in studies of latent-image distribution. Samples of five representative emulsions differing in silver halide composition and grain shape were each treated in solutions which would have constituted conventional, surface-image and internal-image developers if developing agents had been present. The effects of latent-image bleaches were also studied. Normal and extended times of treatment were given in many cases, with some variations in the concentration of active constituents. The main conclusions reached are as follows: (a) Significant etching of emulsion grains occurs with conventional developers, with the addition of recrystallization in the case of chloride emulsions. Etching is increased considerably on omission of bromide. (b) Surface developers have negligible efTects on emulsion grains other than in the case of silver chloride. (c) Etching and recrystallization ofsilver halides by latent-image bleaches may occur. This may lead to the undesirable removal of latent-image specks from sites within a grain. (d) Sodium thiosulphate reveals internal image by etching whereas potassium iodide achieves this by inducing recrystallization. The lalter process is to be preferred in principle, but it would appear that the extent of the reaction varies considerably through the thickness of an emulsion layer. (e) The higher reactivity of silver chloride compared with that of silver bromide and iodobromide is emphasized. This may require some care in the formulation of solutions for use with chloride emulsions and in the interpretation of results obtained by their use.