Silver Halide Emulsions Research Articles

The Cluster Mechanism in Sulphur Sensitization

. The production of silver sulphide on two cubic silver halide emulsions has been followed using sodium thiosulphate sensitizer with the outer sulphur atom labelled 35S. It is found that the position of sensitizer adsorption on the silver halide grain has an effect upon its rate of breakdown to yield silver sulphide. The concentration of sensitizer added to the emulsion affects the photographic response. At optimum sensitivity the quantity of silver sulphide present depends upon the initial sensitizer level, the silver sulphide becoming less efficient with increasing sensitizer. Clusters of silver sulphide are probably produced as a result of preferential adsorption of sensitizer by silver sulphide.

The Adsorption of Thiosulphate Ions to Emulsion Grains, and the Role of these Adsorption Ions in Silver Sulphide Formation

AbstractThe adsorption of thiosulphate to the grains of a silver halide emulsion has been studied with the aid of radioactive thiosulphate. The adsorption has been shown to follow a Langmuir isotherm. The amount of thiosulphate adsorbed falls with increasing emulsion pAg, but is not greatly affected by emulsion pH or temperature. In the digestion process, adsorption is necessary before silver sulphide formation can take place, and this breakdown reaction is a first order one with respect to the amount of thiosulphate adsorbed.

Desensitization by Spectral Sensitizers

AbstractIt is well known that high concentrations of spectral sensitizers cause an overall desensitization. The degree of desensitizing action and the percentage of surface coverage, for which a sudden decrease in gamma and sensitivity takes place, are dependent on the structure of the spectral sensitizing dye, on the type of emulsion, on the pAg and on the kind of development.In the discussions about the mechanism of this desensitizing action, the retarding of development caused by the spectral sensitizers as mentioned already by James and Vanselow is often overlooked.In order to get an appreciation of the importance of this factor, the silver halide emulsions were exposed (to blue light) in liquid state. In this way it was possible to compare the action of the dye added before exposure with the dye added after exposure. For some emulsions, desensitization can be attributed to a large extent to a retarding of development, although certain desensitization also occurs during exposure.

Gold Sensitization of Gelatin Silver Halide Emulsions and the Role of Extraguranular Reactions

Gold Sensitization of Gelatin Silver Halide Emulsions and the Role of Extraguranular Reactions

The Role of Gelatin in Photographic Silver Halide Emulsions (IV)

The Role of Gelatin in Photographic Silver Halide Emulsions (IV)

New Sensitizing Dyes for Silver Halide Emulsions

AbstractA new class of spectral sensitizers is described. They belong to the class of cationic polymelhinic dyes, and ore characterized by the presence, in their conjugated chain, of a \/P(+)−C1 = grouping. Corresponding intra-ionic dyes, bearing a certain resemblance to the merocyanines, were also elaborated. All of them include at least one phosphine-methylene grouping in their molecule.

The Role of Gelatin in Photographic Silver Halide Emulsions (III)

The Role of Gelatin in Photographic Silver Halide Emulsions (III)

X-ray Crystallography as a Tool Photographic Research*

Applications of X-ray analysis to a variety of practical and theoretical problems in photographic research are reviewed, together with some original, not hitherto published work. These cover studies on solid solutions of silver halides and the mechanism of precipitation, the influence of environment on the grains, change in lattice dimensions during exposure, growth of photolytic silver and investigations on defects in silver halide emulsions.

The Theory on Photosensitivity and Development in silver Halide Emulsion and its Singnificance for Electrophotography

The Theory on Photosensitivity and Development in silver Halide Emulsion and its Singnificance for Electrophotography

The Rôle of Gelatin in Photographic Silver Halide Emulsions (I)

The Rôle of Gelatin in Photographic Silver Halide Emulsions (I)

The Rôle of Gelatin in the Photographic Silver Halide Emulsions.(II)

The Rôle of Gelatin in the Photographic Silver Halide Emulsions.(II)

Rates of Solution of Silver Halide Emulsion Crystals

Rates of Solution of Silver Halide Emulsion Crystals

Very Rapid Processing of Oscillograph Records

AbstractA processing technique is described which permits access to a photographic image less than one second after exposure. Applied in a “magazine processor” attached to an oscillograph, the process retains the advantages of speed and permanence enjoyed by silver halide emulsions. Developer is spread in a layer a few ten-thousandths of on inch thick on the recording paper immediately after exposure. The record is then run over a platen maintained above the boiling point. This accelerates development and flash-dries the paper. This gives a result which is stable indefinitely in normal ambient conditions. It may subsequently be stabilized or fixed in daylight to improve contrast. Some of the considerations in the design of the process and the equipment are discussed.

Some Effects of Gelatin on the Adsorption of Sensitizing Dyes on Silver Halide Grain Surfaces*

AbstractStudies of the effect of the gelatin content of the suspension medium of silver halide emulsions show that sensitizing dyes added to such emulsions enter into adsorptive competition with a gelatin layer at the grain surface, which, at sufficiently high concentration of most sensitizers, appears to be completely displaced by the dye. Illustrative adsorption isotherms of representative carbo-cyanines, merocyanines, and other sensitizers as a function of the gelatin concentration of thesuspension medium are provided. Direct proof of the displacement of gelatin from the grain surface is obtained from nitrogen determinations on dyed and undyed grains.The isosteric heat of adsorption of dyes to emulsion grains, computed from the temperature coefficient of adsorption, is considerably higher in emulsions of low gelatin content than in normal emulsions. An interesting feature is the increase in the heat of adsorption found to accompany the onset of co-operative adsorption of one of the dyes studied.

Method of photographic demonstration of penetrant corpuscular rays in human tissue

It is proposed to register the penetration of cosmic rays into biological material by the photographic emulsion technique. From a study of the tracks, an examination of the biological effects of cosmic rays would be possible. To introduce the particle-sensitive material into the cellular tissue, a small amount of liquid silverhalide emulsion is injected. After processing, this should then serve as indicator for penetrated particles. Preliminary tests were carried out on dead human skin, into which a few of emulsion were injected. The specimens were then dried, exposed to a beam of neutrons and developed by temperature-development. Microscopic inspection of thin sections from different specimens shows, in reproducable manner, tracks of recoil protons. Further experiments are to be carried out on living material.

Energy Transfer in the Photo-Sensitization of Silver Halide Photographic Emulsions: Optical Sensitization, Supersensitization, and Antisensitization

Many facts concerning optical sensitization of silver halide photographic emulsions point to the importance in the sensitization process of the migration of excitation energy from a dye molecule primarily excited by radiation to neighboring molecules in a cooperative layer. Individual dye molecules, however, appear capable of transferring energy to the silver halide without the intervention of energy migration, often with high efficiency, as is shown by relatively high quantum yields of sensitization at low concentrations of dye. If, as a result of increase in the concentration of dye, the sharp absorption bands indicative of exciton migration appear, the efficiency of transfer tends, in fact, to fall. Dyes in the cooperative state, however, are most susceptible to the increase of sensitization caused by supersensitizers. The regular periodic field which favors exciton migration decreases the probability of energy transfer to the halide, and the supersensitizer appears to act as a perturbation of this field at which the moving exciton is slowed down so as to facilitate transfer. Consistent with this explanation is the high quenching power of supersensitizers on the fluorescence sometimes exhibited in solution and in the adsorbed state by cooperative aggregates of dye molecules. The inverse of supersensitization, antisensitization by relatively small amounts of nonplanar dyes, is also observed. Here the migrating energy in the cooperative layer is dissipated as heat by the perturbing molecule, and is prevented from reaching the silver halide. Experimental evidence supporting these conclusions is furnished in detail, including correlations between optical sensitization and supersensitization with the type of absorption spectrum of the adsorbed dye; the relations between the concentration of sensitizer, supersensitizer, and antisensitizer, and the efficiency of super- and antisensitization; the quenching of fluorescence of sensitizers by both types of perturbing molecules; and effects of nonplanar dyes on the photoconductivity of optically sensitized silver halide emulsions analogous to their photographic effects.

Some Remarks on Gold Treatment of Photographic Silver Halide Emulsions

Earlier attempts of various investigators to increase the sensitivity of photographic emulsions by addition of colloidal silver, silver sulfide, or gold are reviewed. Koslowsky’s discovery of the effect of certain gold complex salts as powerful sensitizers is described and a possible mechanism of the effect discussed. The importance of this effect for the manufacture of modern high speed and fine grain film as well as special x-ray emulsions is indicated.

Optical sensitizing of silver halide emulsions. I Adsorption of orthochrome T to silver bromide

Optical sensitizing of silver halide emulsions. I Adsorption of orthochrome T to silver bromide

The Optical Sensitizing of Silver Halide Emulsions. I. The Adsorption of Orthochrome T to Silver Bromide

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Optical Sensitizing of Silver Halide Emulsions. I. The Adsorption of Orthochrome T to Silver BromideS. E. SheppardS. E. SheppardMore by S. E. Sheppard and H. CrouchH. CrouchMore by H. CrouchCite this: J. Phys. Chem. 1928, 32, 5, 751–762Publication Date (Print):May 1, 1928Publication History Published online1 May 2002Published inissue 1 May 1928https://doi.org/10.1021/j150287a007RIGHTS & PERMISSIONSArticle Views34Altmetric-Citations15LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (414 KB) Get e-Alerts

On a supposed relation between the sensitizing of silver halide emulsion and the bleaching-out of dyes

On a supposed relation between the sensitizing of silver halide emulsion and the bleaching-out of dyes