Silver Halide Emulsions Research Articles

The Photocurrent in Silver Halide Emulsion Grains as Determined by the Dember Effect

AbstractThe explanation for the direction of photocurrent due to the Dember effect in silver halide emulsion grains is given for the situations where spectrally unsensitized silver halide grains were exposed to blue light and spectrally sensitized grains to green-red light.The change of the Dember effect by varying the condition of the emulsion grains, that is, atmospheric condition, preexposure, chemical sensitization and desensitization, temperature dependence of photovoltage relaxation, the wavelength of the incident light and the ionic conductivity of silver halide grains, was observed and discussed.

Photographic Effects of Electron and Positive Hole Traps in Silver Halide Emulsion Grains

AbstractExaminations were made on the photographic effects of various electron and positive hole traps including sensitivity specks of chemical sensitizations, metal ions, and various dyes, showing that the photographic elfecls were markedly dependent upon the natures of the traps and emulsion grains used. It was indicated that photographic speed of grains was increased by traps only under the specific condition that the traps could be helpful for the increase of the efficiency of latent image formation at the surface of the grains.

ChemInform Abstract: STUDIES ON CYANINE DYES. I. SYNTHESIS OF NEW OXACYANINE DYES

AbstractAus dem Diaminochinon (I) erhält man durch reduzierende Acylierung die Substanz (II), die man zu (III) cyclisiert und weiter zu (IV) quaterniert.

Surface physics of silver halides

Since the inception of photography over a century ago, the silver halide emulsion grain has remained central to the photographic process. Much effort has been devoted to the improvement of the silver halide grain in terms of increased sensitivity, spectral response and development processes. The ability to use silver halides effectively in commercial products was established long before an actual understanding of the physical process was achieved. In the 1960s, research progressed on the bulk characteristics of silver halide single crystals. The electron and hole mobilities, the mechanism of ionic conductivity and the optical properties were among the major areas where mechanistic conclusions were drawn. Much of this work has recently been reviewed by Brown. ~1) An understanding of the bulk proved only a first step towards a fuller knowledge of the photographic process. Since an emulsion grain may range in size from a few tenths of a micrometer to a few micrometers, many of its properties must be dominated by its surface structure. A concerted research effort on silver halide surfaces did not develop until the late sixties. Some of the delay in studying the surface properties was caused by the nature of the surface itself. Silver bromide crystals, for instance, could not be easily cleaved, even at very low temperatures. Moreover, owing to its inherent softness, at tempts to obtain a smooth surface by polishing usually resulted in such surface disruption that no Laue X-ray diffraction pattern was seen. This fact, combined with the photosensitivity of the silver halides, made annealing in a bromine atmosphere almost a prerequisite to any sui'face study. It was only with the advent of sheet crystals and evaporated epitaxial films that well-defined surfaces could be obtained without the necessity of laborious surface treatment. Hence, this review will concentrate on some of the recent developments in experimental and theoretical investigations of silver halide surfaces. In particular, the discussion will be focused on the silver hal ide-vacuum surface since the knowledge of this interface is more advanced than that of silver halide-solution interfaces. The physical structure of the surface as well as the subsurface region will be examined in detail. Other aspects of silver halide research have been discussed in recent reviews by Hamilton on the photographic process

Erratum to : Photocurrent in Silver Halide Emulsion Grains by Dember Effect (II)

Erratum to : Photocurrent in Silver Halide Emulsion Grains by Dember Effect (II)

Bleach-Enhanced Fog and Reduction Sensitization

AbstractFogging of a silver halide emulsion by bathing in a dilute solution of a latent image bleach (bleach-enhanced fog, BEF) has been inve tigated on a series of bromide and iodobromide experimental emulsions. None of the emulsions showed B F in the absence of any deliberate sensitization or when only sulphur ensitized, but with the exception of a cubic bromide emulsion, all showed BEF when either reduction sensitized or sulphur-plus-reduction sensitized. Distribution of BEF between surface and interior depended on the same grain structure and sensitizing conditions that inOuenced latent image distribution. The presence of a desensitizing dye during bleaching prevented BEF. For surface BEF the solution that fogged the emulsionlaler destroyed the fog centres.It is proposed that BEF occurs when the concentration of oxidizing agent is sufficiently low 10 make thermal regression of a speck which has heen reduced in size 10 a single silver alom more probable than bleaching of the silver atom. Tili results i...

Studies on cyanine dyes. I. Synthesis of new oxacyanine dyes

AbstractSynthesis of new types of bisoxacyanine dyes covering styryl‐, mero‐, and methine cyanines was achieved by interaction of 2,6‐dimethylbenzdioxazole 3,7‐bis‐ethyl iodide with active carbonyl components. These dyes showed high absorption spectral properties and were found to induce remarkable sensitisation effects when applied to silver halide emulsions.

The Action of Polyethylenimine on the Formation and Physical Ripening of Silver Chloride and Silver Bromide

AbstractPossibilities of partial or total substitution of gelatin in photographic silver halide emulsions were studied in many laboratories. Much attention was paid to synthetic polymer. The author reports some resuils obtained with polyethylenimine as a protective and physical ripcning agent for preparation of silver chloride and silver bromide suspention, Precipitation and partiele growth in the suspention were investigated by turbidimetry and electron photomicrography. Contrary to previous statements in the literature, polyethylenimine was found to be a good protective colloid and an effective regulator for physical ripening of silver halides in aqucou systems.

Development by Means of Electrode Reduction of Individual Silver-Halide Emulsion Crystals*

"Development by Means of Electrode Reduction of Individual Silver-Halide Emulsion Crystals*." The Journal of Photographic Science, 23(3), pp. 131–132

BOOK REVIEWS

Book Reviewed in this article:THE NATIONAL GRAVITY REFERENCE NET 1973 (NGRN73). By D. Masson Smith, P. M. Howell, A. B. D. E. Abernethy‐Clark and D. W. Proctor (Editor). Ordnance Survey Professional Paper No.THE PRECISE ALIGNMENT SURVEY OF A 5 KM RADIO TELESCOPE AERIAL ARRAY FOR THE CAVENDISH LABORATORY, CAMBRIDGE UNIVERSITY. By W. J. Preiss, D. W. Proctor and P. E. Haywood. Ordnance Survey Professional Paper No.REMOTE SENSING EVALUATION FLIGHTS, 1971. Part 1 edited by L. F. Curtis and A. Mayer; Part 2 edited by J. G. W. Greenwood.PHOTO‐HYDROLOGICAL RECONNAISSANCE SURVEYS. By A. M. J. Meijerink.EVIDENCE IN CAMERA. The story of photographic intelligence in World War II. By C. Babington Smith.STABILIZATION OF PHOTOGRAPHIC SILVER HALIDE EMULSIONS. By E. J. Birr.

New Photographic Material for Printed Circuits

Recently a number of new photographic systems have been investigated with the object of replacing the conventional silver halide emulsions and as such could possibly represent the basis for further development of new methods of production for printed circuits. By using prepared combinations of metal and a light sensitive substance, e.g., arsenous sulphide/silver and cadmium iodide/tin, one can obtain directly a positive metal image. This approach by the authors was used for the development of a new direct positive photographic material for printed circuits which is easily processed and can be safely stored.

Photocurrent in Silver Halide Emulsion Grains by Dember Effect (II)

Photocurrent in Silver Halide Emulsion Grains by Dember Effect (II)

High−sensitivity optical recording in KTN by two−photon absorption

Birefringence changes are induced in a cubic potassium tantalate niobate crystal with an external electric field by two−photon absorption of picosecond optical pulses. The recording sensitivity of 100 μJ/cm2 for elementary holograms with a few percent reconstruction efficiency is comparable to the sensitivity of holographic silver halide emulsions. The high sensitivity of KTN is shown to be due to efficient charge transport of photoexcited carriers.

Photoconductivity Measurements of Silver Halide Emulsion Grains by Dember Effect

Photoconductivity Measurements of Silver Halide Emulsion Grains by Dember Effect

The Theory of Photographic Sensitivity of Silver Halide Emulsion

The Theory of Photographic Sensitivity of Silver Halide Emulsion

Additional Formation of Silver as a Result of an Infectious Development of Silver Halide Emulsions*

AbstractDeveloping mixtures of unexposed and exposed emulsions yield a considerable amount of co-developed silver halides of the unexposed emulsion. The lower the gelatin silver bromide ratio the more pronounced this phenomenon becomes. either chemical sensitization nor crystal habit of the unexposed Ag-halide influence the amount of additional formed silve during development in a normal rapid processing X-ray developer.The grain size of the unexposed crystal, the internal developability and the relative log E value at the expo lire play an important role. Solution physical development must be discarded as a cause of this co-development, taking into account the rather high covering power of the co-developed silver.

Effects of moisture, oxygen, baking, and water-hypersensitization on the sensitivity of Kodak spectroscopic plates, types IIIa-J, IV-N, and I-N

view Abstract Citations (7) References (7) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Effects of moisture, oxygen, baking, and water-hypersensitization on the sensitivity of Kodak spectroscopic plates, types IIIa-J, IV-N, and I-N Babcock, T. A. ; Ferguson, P. M. ; James, T. H. Abstract The individual effects of oxygen and moisture on the photographic sensitivity of a model silver halide emulsion and of Kodak spectroscopic films and plates, types IIIa-J, IV-N, and I-N were examined. The relation of the effects of oxygen and moisture to techniques such as baking of IIIa-J films or hypersensitizing IV-N plates is also discussed. It is found that baking vacuum-outgassed IIIa-J film in dry oxygen gas, followed by evacuation, or cycling a high-humidity, oxygen-free environment can yield increases of sensitivity as large as or larger than can be achieved by baking under vacuum or in a dry, inert atmosphere. A technique of exposing an infrared plate, such as Kodak spectroscopic plates, type IV-N, or I-N in a high-humidity, oxygen-free environment, appears to be an efficient means of achieving hypersensitization without the fog increases or nonuniformities caused by liquid water hypersensitization. Publication: The Astronomical Journal Pub Date: January 1974 DOI: 10.1086/111536 Bibcode: 1974AJ.....79...92B full text sources ADS |

The Nature of Photographic Sensitivity and the Mechanism of Formation of the Latent Image

In a new physical-chemical theory of the photographic process in silver-halide emulsions, the model system is regarded as a supersaturated solid solution of metallic silver in the silver halide. The silver arises mainly as the result of chemical sensitization, while the existence of an energy barrier to the formation of nuclei of a new solid silver phase causes supersaturation. This barrier leads to the appearance of two different types of silver speck: primary centres (silver atoms and aggregates of a few silver atoms), and secondary centres (colloid silver particles).The energy barrier can be overcome and silver nuclei of a critical size formed in two different ways: (a) by the absorption of photon energy to give latent-image silver, and (b) by spontaneous fluctuations.Contradictions appearing in the older theories of the photop,raphic process are reviewed and it is shown that they are successfully dealt with by the new theory, the various effects considered arising from the interplay of factors influencing the degree of supersaturation and the lowering or surmounting of the barrier to nucleation.

Characteristics of Silver Halide Emulsion for Hologram (1)

Characteristics of Silver Halide Emulsion for Hologram (1)

Influence of the Habit of Silver Halide Crystals on Absorption Spectra of Adsorbed Sensitizing Dyes: I. Bromide and Iodobromide Emulsions

AbstractIt is a well known phenomenon that the absorption spectrum of an adsorbed dye in silver halide emulsions can show different maxima, depending on the structure of the dye itself and on the adsorbing crystal surface.In the present study the impact of the grain habit of silver bromide and silver iodobromide on the absorption spectrum of several carbocyanine dyes was examined. The results prove that J-aggregation is generally favoured by an octahedral habit. A model for J-band formation is proposed.The influence of incorporated iodide ions is due to the change of the crystal habit rather than to a direct impact on the absorption Spectrum.