Silver Chloride Emulsion Research Articles

Characterization of contemporary artworks made on photosensitized canvas by means of optical microscopy and micro-Raman spectroscopy techniques

Contemporary artists experimented with a wide range of techniques as it is photography, combined with other materials so as to create images on various surfaces. Nikos Kessanlis (1930–2004), an eminent Greek artist, used photographic and mechanical techniques, involving the application of a photosensitive emulsion on different supports for his artistic creations. This photomechanical technique is called alternative printing.The present study examines a series made by Kessanlis in 1999–2000, composed of eleven panels of photosensitized canvases with the scope to identify the materials used by the artist (canvas, primer, photographic emulsion, protective layer), to understand the artist’s technique and to document the panels overall condition. The series is examined using non-invasive techniques (portable digital optical microscope) and analysis of micro-samples by–micro-Raman spectrometry.Micro-Raman analysis results identified the support, as canvas made by cotton and jute, the primer layer as a combination of titanium white and calcium carbonate and finally the photosensitized layer, as a gelatin silver chloride emulsion. Also further compounds are detected such is silver sulfide, related to the photosensitized emulsion deterioration and soot and lignin, related to the impure environment (air flow inside the metro station) where the series are on display for the last twenty years (Athens metro station).Finally, measurements of air temperature and relative humidity are also performed for a short period near the panels so as to evaluate the environmental conditions of the area. The results have shown extreme daily fluctuations of both factors, characterized by “cycling” that could be related to mechanical and chemical deterioration factors affecting the artwork condition.

The Quantum Yield of Silver Production in the Photolysis of Silver Chloride Emulsion

The Quantum Yield of Silver Production in the Photolysis of Silver Chloride Emulsion

Synthesis of Ag2S nano-sized clusters and their chemical sensitizations in AgCl cubic and {100} tabular microcrystal imaging systems

In recent years much attention has been devoted to AgCl emulsion owing to its serial advantages and inimitable potential. But in the research of this emulsion a thorny problem remains unsolved till now, which is the improvement in sensitivity is always accompanied with high fog density. In this work 5 nm Ag 2 S particles were prepared and used as novel sensitizers in AgCl cubic and {100} tabular microcrystal emulsions. The novel sensitizer shows an effective sensitizing ability for silver chloride emulsion, and it is superior to the traditional Na 2 S 2 O 3 sensitizer because by using it comparatively high sensitivity can be obtained with lower fog density. So the above sensitizing problem is going to be effectively solved. To discover the evolution mechanism of the sensitizer clusters and explain their excellent sensitizing properties, diffuse reflectance spectroscopy (DRS) was used as a probe on the AgCl microcrystal surface.

The Order of Addition of 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene and Dyes into Silver Chloride Emulsion

This study examined the supersensitization of 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene (TAI) in silver chloride emulsions. A systematic investigation on the concentration of TAI and the order of adding TAI and dyes had been carried out. It was discovered that the supersensitization efficiency of TAI varied greatly with the order of adding TAI and the concentration of TAI. The spectrometry study suggested that TAI could intensify the formation of the J-aggregate of dye and had quite different effects on the absorption spectra and spectral distribution of emulsion sensitivity when added in different orders.

On the Mechanism of the Delayed Formation of Latent Image Caused by Iridium-Doping into Silver Chloride Emulsions

On the Mechanism of the Delayed Formation of Latent Image Caused by Iridium-Doping into Silver Chloride Emulsions

A Study of Developing Speed of Silver Chloride Emulsion

A Study of Developing Speed of Silver Chloride Emulsion

Electron nuclear double resonance study of pure and aquated rhodium complexes in silver chloride emulsions

Detailed information has been obtained on the structure of pure and aquated complexes in AgCl using multifrequency EPR and powder ENDOR spectroscopy. Because of the anisotropy of the centre g matrix it was possible to selectively excite centres with a specific angle between the z axis of the g matrix and the magnetic field axis. As a result, almost single-crystalline-like ENDOR spectra were obtained and the angular dependence of the ENDOR spectra could be obtained by scanning the magnetic field over the range of the EPR spectra. Three different centres were detected that are distinguished by different thermal stabilities, different parameters of the g matrix and the hyperfine matrices of the central Rh nucleus and ligand H, Cl and Ag nuclei. A pure centre without ligands could only be generated in an emulsion where great care was taken to prevent the aquation of the dopant ion in the dopant solution and during the precipitation. This centre had the highest thermal stability. In an emulsion prepared conventionally two centres were found that are associated with one and two ligands bound to the ion in the plane perpendicular to the g matrix z axis. Using the results of the EPR and ENDOR analysis in combination with the results of a total energy calculation two models are proposed that contain the positions of the ligands and the charge compensating vacancies.

Sorption-Purified Gelatins in Silver Chloride Photographic Emulsions

We study the effect of deeply sorption-purified gelatins on the crystallographic characteristics and chemical ripening of silver chloride emulsions containing cubic and tabular microcrystals.It is shown that during emulsion synthesis using purified gelatins, an increase in the average microcrystal size was observed, whereas in the case of tabular microcrystals, a fraction of the latter (St) was found to grow significantly.The rate of the chemical ripening reaction in the presence of purified gelatins but without chemical ripening agents slowed down, whereas the use of these agents contributed to its noticeable increase.A relationship between the substances removed during sorption purification and the effects observed has been followed.

5-Methyl-7-hydroxy-1,3,5-triazaindolizine as Sensitizer in Silver Chloride Emulsion

This study examines the influence of 5-methyl-7-hydroxy-1, 3,5-truaaindolizine (TAI) on the sensitivity of AgCl emulsion. The results indicate that TAI can increase the sensitivity of unsensitized and sulylmr-sensitized AgCl emulsion, regardless of the methods of introducing TAI and it acts not only as a sensitizer hut also as a stabilizer. Investigations by cyclic voltammetry of the adsorption of TAI on AgCl grains show two kinds of adsorption: physisorplion and chemisorption. The measurements of dielectric loss of silver grains show that the adsorption of TAI decreases the conductivity of AgCl grains. The mechanism of sensitization by TAI is suggested to be a result of the adsorption of TAI and the formation of silver salts of TAI on the surface of the grains, which cause the decrease of ion conductivity and the change of charge distribution of the grains, leading to the improvement of the sensitivity.

Photographic Action of Ph(II)-EDTA

AbstractBy turbidimetric and electron-microscopic methods the influence of Pb(II)-EDTA on the physical ripening of silver bromide and silver chloride emulsions, obtained in excess of halide or silver ions, was investigated. The effect of Pb(II)- EDTA on the photosensitivity, S, the contrast, and the maximum density, Dm, was also studied. The reagent was found to perform as an active sensitizer when introduced at a concentration of 2 × 10-4 M prior to precipitation.Investigations on hypersensitization were carried out by a known method for hypersensitization with Pb(II)-EDTA. It was also shown that Pb(II)-EDTA can be applied in practice as a hypersensitizer as well as a sensitizer.

Comparative Study of the Sensitivity Specks Formed During the Ripening of Silver Chloride Relative to Silver Bromide with Gold-198 and Gold-198 Plus Sulphur-35*†

AbstractBy means of radioactive tracers 35S and 198Au a comparative study of the composition of the sensitivity specks formed during the ripening of silver chloride and silver bromide emulsions with equal grain size (a = 0.2 //m) was made and related to their photographic response. The sensitizers used were gold chloride (198Au) and gold chloride combined with sodium thiosulphate (35Sext).A washing technique was required to differentiate between gold in a more or less soluble state adsorbed on the emulsion grains during ripening. A 10-4 M sodium sulphite solution was found to be useful. This gold-complexing solution was able to desorb gold ions from the grain surface, leaving undesorbed the presumed gold sulphide, silver gold sulphide, gold or gold oxide specks.The following conclusions could be drawn:(1) The ripening of silver chloride and silver bromide emulsions with gold chloride results in the formation of identical amounts of non-desorbable gold, but corresponding with higher fog values for the AgCI...

Using silver chloride emulsions as adaptive optical filters for image processing

Fine-grain high-sensitive silver chloride emulsions with “print-out” effect were synthesized for the purposes of adaptive amplitude spatial frequency filtering of images. Their characteristics were studied and experiments were conducted for contrast enhancement and contouring.

Reciprocity Law Failure in Silver Halide Emulsions

AbstractThe influence of the pAg during ripening and of restoring the pAg after ripening on the reciprocity failure in silver bromide and silver chloride emulsions of equal grain size and grain distribution is studied.In the AgBr emulsion, sulphur ripening at lower than normal pAg values causes a strong decrease of the high intensity reciprocity law failure (HIRF). From this we conclude that silver sulphide specks no longer function as an electron trap at high intensities.

Anisotropy induced in a silver chloride emulsion by two successive beams of white light perpendicularly polarized

This paper is a study of the anisotropy induced in a silver chloride photographic emulsion by two successive beams of white light, linearly polarized at right angle. After the first exposure, the colloidal medium contains silver ellipsoids e generated by the photolysis of silver chloride and silver ellipsoids e b resulting of the partial destruction of some of the previous ones by long wavelengths. This medium is then illuminated by the second beam linearly polarized at right angle of the first beam. Short wavelengths induced silver ellipsoids e′ identical to the ellopsoids e but rotated through π/2 with respect to them. As in the first exposure, some of them are partly broken up and transformed into ellipsoids e′ b identical to ellipsoids e b but the direction of their major axis. Moreover, the long wavelengths of second exposure transform some of the particles e and e b generated during the first exposure, into smaller ellipsoids e eb and e bb. Finally, the colloidal medium resulting of these two exposures, contains silver chloride and six sorts of silver particles. By calculating the indices of the medium, we show that the wavelengths characterizing the zero birefringence and zero dichroism of the emulsion are dependent on the energies recorded during each of the exposures.

Application of weigert effect to the pseudocoloration of a black and white signal

We propose here a method to transform the grey levels of a black and white transparency into different colours. The transparency to be processed, illuminated by a beam of linearly polarized white light, is twice recorded on a photograph silver-chloride emulsion. The direction of the light vector is rotated through π/2 between the exposures. The resulting plate is characterized by a spatially varying anisotropy. The main point is that the wavelength λ B and λ D, respectively corresponding to the cancellation of birefringence and dichroism, are function of the irradiance of the signal and of the successive exposure times. The plate is then illuminated in white light and observed between two polarizers P and A. It reconstructs an achromatic image of T when the respective axes of P and A are mutually perpendicular. A rotation of A from its setting crossed with P generate a colour distribution on the plate.

Anisotropic response of a silver chloride emulsion printed out by linearly polarized achromatic signal

We describe the anisotropic response of a silver chloride photographic emulsion after exposure to a linearly polarized achromatic signal. As it is described in previous papers, such a plate is a uniaxial medium with its optic axis parallel to the direction of the light vibration that induced anisotropy. It exhibits dichroism and birefringence, which are respectively equal to zero for two wavelengths independently of the exposure time. We calculate the refractive and absorption indices of such a colloidal medium following a method proposed by Garnett in 1905. The medium is assumed to be formed by three kinds of particles: silver chloride isotropic particles, silver isotropic particles generated by the action of linearly polarized short wavelengths on the silver chloride, and ellipsoidal silver particles resulting from the partial destruction of the previous ones by the linearly polarized long wavelengths. Finally, the amplitude response of the plate consists of two terms: an isotropic term that characterizes the isotropic darkening of the plate, which decreases linearly when exposure increases, and a term, which is proportional to the square of the exposure, that characterizes the anisotropic bleaching of the plate. Finally, we investigate the polarity of the signal reconstructed from the anisotropic recording of a black-and-white transparency. We show that the polarity is always the same as that of the original object, whatever the wavelength of the reading beam may be, when the plate is observed between crossed polarizers.

Image deblurring methods using the Weigert effect

Two simple methods are described to improve the quality of images blurred by either defocusing or a uniform rectilinear motion of the photographic plate during the exposure. They both consist of simultaneously recording on a silver chloride emulsion two incoherent images of the input blurred signal, perpendicularly polarized and conveniently slightly shifted. The strength of anisotropy induced in the plate is proportional to the difference between the intensities of the images, i.e., to the derivative of the input signal. In the case of defocusing, the two images are radially shifted and one reconstructs, after exposure, the contours of the input signal. In the case where the degradation is due to a uniform rectilinear motion, the two images are laterally shifted and the reconstructed signal consists of two images of the original object.

Spatial differentiation of an intensity distribution using the Weigert effect in a silver chloride emulsion

The authors describe a method for extraction of the one-dimensional derivative of an intensity distribution. The difference between two laterally shifted images of the transparency to be processed is recorded in terms of an induced anisotropy in a silver-chloride emulsion. The derivative is turned out by observation of the emulsion between crossed polarizers. Positive or negative parts of it will be alternatively exhibited by suitable rotation of the analyser.

Anisotropy induced in a silver-chloride emulsion by two incoherent and perpendicular light vibrations

After a report on the composition of two incoherent rectilinear vibrations with perpendicular polarizations, we suggest in this paper a method of extraction of the difference between two images in incoherent and polarized light. The images, perpendicularly polarized, are simultaneously recorded on a silver chloride emulsion H where an optical anisotropy is induced only in the areas where the incident intensity distributions are not identical. After exposure, H, observed between crossed polarizers, displays the difference between the two original images in its image plane. In addition, it is shown that the sign of this difference is retrieved by means of the dichroism of the plate.

Application of the weigert effect to the contrast reversal of a black and white transparency

Bleaching of a high resolution photographic plate, previously strongly illuminated and processed, forms a photosensitive silver-chloride emulsion which becomes anisotropic after exposure to polarized light (Weigert effect). The resulting anisotropy is partial and the birefringence of the plates is zero for a given wavelength in the yellow region of the visible spectrum. We suggest an application of the phenomenon to the contrast reversal of a black and white transparency.