Table of Content

20 November 1991, Volume 9 Issue 4

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A STUDY ON LATENT IMAGE FORMATION BY THE COMPUTER SIMULATION TECHNIQUE Ⅲ. THE EFFECT OF CHEMICAL SENSITIZATION

ZHAO JING-QUAN, XIA PEI-JIE

1991, 9(4):  241-248.  DOI: 10.7517/j.issn.1674-0475.1991.04.241

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This paper deals with the mechanism of latent image formation on chemical sensitized emulsion based on the model proposed in the previous paper. From the current work, some results were obtained: (1). silver sulfide specks on the surface of a silver bromide grain can be photoelectron traps and photohole traps at same time. As photoelectron traps, they are in larger dimension than the single kink site, however they are not deep ones like the single kink site. It is these specks which help the emulsion to promote photographic sensitivity and improve LIRF> but they should also be responsible for despersion of photolyzed silver atoms and HIRE. As photohole traps, their only function is slowing down the photohole movement and delaying the bromine formation but can not remove photohole permanently. (2). Gold sensitization not only can decrease the size of minimum developable centers but also increase the anti-oxidization ability of the clusters, furthermore, there should be other sensitization mechanisms which we still do not know. Ag₂ can be partly thansformed into developable centers through gold-intensification. (3). The nature of the silver specks formed from reduction sensitization is same as that formed during exposure. This do not mean they must grow up, in fact, most of them would be destroyed during exposure. Two important functions of reduction specks are to increase the probability of latent image formation and remove photoholes or bromine therefore increase the number of net electrons in the grains which is especialy in favour of latent image formation.

STUDY ON THE STRUCTURE AND PROPERTIES OF SILVER HALIDE EMULSION MICROCRYSTALS Ⅷ. EFFECT OF THE SHELL THICKNESS OF THE LIGHT ABSORBTI-ON AND ELECTRIC PROPERTIES OF TRUNCATED CUBIC EMULSION MICROCRYSTALS

ZHOU XIAO-HONG, LI ZHEN-XING, PENG BI-XIAN, YUE JUN

1991, 9(4):  249-254.  DOI: 10.7517/j.issn.1674-0475.1991.04.249

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A series of truncated cubic emulsion microcrystals with different shell thickness was prepared by double-jet method with automatic control of pAg. The grain size and its distribution were measured with combined optical microscopy and image processing technique. Their relative light absorption was determined by UV spectrophotometry. Their ionic and photo-electron conductivity were determined with the dielectric loss and microwave photoconductivity methods respectively as a function of shell thickness. It was shown that the relative absorption intensified with the shell thickness increase, but on the contracy, the ionic conductivity droped with Ar increase. The photo-electron conductivity first intensified with Ar increase, passed through a maximum (△r = 1:2.2), and then droped fastly (△r>1:3.5). The corelations between the relative light absorption, electric properties and the sensitometric properties had been presented (Fig.1) and elucidated, the optimum shell thickness for higher sensitivity is shown to be in accordance with the thickness of the surface space charge layer (so called Debye length) of the emulsion microcrystals.

SPECTROSCOPY STUDY OF THE GROUND STATE AND EXCITED STATE OF IODONIUM SALT/AMINE SYSTEMS

HE JUN-HUI, WANG ER-JIAN

1991, 9(4):  255-260.  DOI: 10.7517/j.issn.1674-0475.1991.04.255

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The interactions of iodonium salt with amines in ground state and excited state have been investigated. The formation of ground state and excited charge transfer complexes between iodonium salt as electron acceptor and amines as electron donors was observed. In the case of diphenyliodonium chloride (DPIOC)/triethylamine (TEA) system, the complex formed was determined to be 1:1 molar ratio and its association constant and molar extinction coefficient were equal to 2.2×10 (mol/l)^-1 and 2.8×10³ mol^-1·1·cm^-1 respectively. The experimental results also showed that with increasing of electron-donating ability of amines, the absorption maximum of charge transfer complex occurs a red-shift, however, with increasing of steric volume of amines, the molar extinction coefficient decreases due to the unfavorable steric hindrance.

THE AUTOCATALYTIC NATURE OF LITH DEVELOPMENT

JI SU-XUE, MA FENG-YUN, HU PING, REN XIN-MIN

1991, 9(4):  261-265.  DOI: 10.7517/j.issn.1674-0475.1991.04.261

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Different from conventional development, Lith development proceeds with parallel pattern of grain population reduction over a wider range of exposure. If sequential pattern of grain reduction occurs, the density growth only gives information about the distribution of development induction period among grains. Only when parallel pattern of grain population reduction occurs, the density growth gives information about the rate at which a single grain develops. In other words, only when all the developable grains in emulsion layer develop in parallel, the whole layer will have the same developme nt kinetics as that of a single grain and this makes the whole process autocatalytic in nature. So the autocatalytic nature of Lith development can be attributed to the parallel pattern of grain population reduction.

KINETICS OF DIFFUSION WITH CHEMICAL REACTIONS IN A GELATIN LAYER (Ⅰ) NUMERICAL MODELING OF DIFFUSION AND DIFFUSION WITH A FIRST-ORDER REACTION

XIA PEI-JIE, ZHAO WEN-FANG, Mo YI-BO

1991, 9(4):  266-272.  DOI: 10.7517/j.issn.1674-0475.1991.04.266

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In this paper numerical modeling was used to investigate kinetics of diffusion and diffusion with a first-order reaction in a gelatin layer, with which the space distributions of a diffu-sant in a gelatin layer at different times were obtained. The advantages of these computerized models over the conventional analytical method were: 1) easier to find numerical solutions; 2) of more potential to study rather complicated processes of diffusion with chemical reactions in gelatin layer. In order to verify the reliability of these models, the cooresponding analytical solutions were used by comparison.

KINETICS OF DIFFUSION WITH CHEMICAL REACTIONS IN GELATIN LAYER (Ⅱ) NUMERICAL MODELING OF DIFFUSION WITH A SECOND-ORDER REACTION

XIA PEI-JIE, ZHAO WEN-FANG, Mo YI-BO

1991, 9(4):  273-280.  DOI: 10.7517/j.issn.1674-0475.1991.04.273

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A numerical model was designed to describe kinetics for a reactant to diffuse with a second-order reaction with another reactant in a gelatin layer. Using the combination of the model with corresponding experimental observation, the important kinetic parameters, the diffusion coefficient and the rate constant could be obtained. When all of kinetic parameters were available, the model could reproduce the kinetic curves obtained from experiments and give some information on intermediate processes, such as the space distributions of reactants and product with different times. This model might be considered as a quite powerful tool to analyse and study the processes of diffusion with chemical reactions in gelatin layer.

THE DISTRIBUTION OF LATENT IMAGE AND SABATIER EFFECT IN CORE-SHELL EMULSION

XIE BO-PING, ZNUANO SI-YONG, TAO CHUN, REN XIN-MIN

1991, 9(4):  281-289.  DOI: 10.7517/j.issn.1674-0475.1991.04.281

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The distribution of latent image and the Sabatier effect of two groups of monodisperse silver iodobromide emulsions were studied. The emulsions in one group were common monodisperse emulsions in which 10 mol% iodide was uniformly distributed within the grain, and the emulsions in the other group were core-shell emulsions of which the designed composition was 20 mol% iodide in the core and 0 mol% iodide in the shell. The total iodide contents of the grain in the two groups of emulsions were equal. Both groups of emulsions were chemically sensitized by sulfur plus gold and sulfur plus gold plus iridium, respectively. Simple etch method of partial dissolution and surface development was used to reveal the distribution of internal latent image. It is found that the surface sensitivity as well as the internal sensitivity of the core-shell emulsions are greater than that of the corresponding uniform silver iodo-bro-mide emulsions. It is noticed that there are reversals of internal image only in the core-shell emulsions. The study of the Sabatier effect combined with the determination of internal image distribution shows that an emulsion that shows good Sabatier effect should contain grains with enough surface as well as enough internal sensitivity centers, and they should be well matched.

ELECTROCHEMICAL MEASUREMENTS UPON PQ DEVELOPERS

LIU QUAN, ZHANG LIN, JIANG ZI-WEI

1991, 9(4):  290-294.  DOI: 10.7517/j.issn.1674-0475.1991.04.290

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With changing the composition and concentration of developers, the behavior of PQ developers is transferred from Lith type to superadditive type. The development is also transferred from Yule’s mechanism to the regeneration mechanism. To support this transferred mechanism, the oxidation current measurements of hydroquinone were given in this paper by cyclo-voltam-metric measurements. The electrochemical measurements in the present paper are in good agreement with Van Veelen’s sensitometric measurements.

THE DETERMINATION OF SURFACE STATE ENERGIES OF CdSe THIN FILM ELECTRODE BY IMPEDANCE ANALYSIS IN LAPLACE TRANSFORMATION

XIAO XU-RUI, LIN YUAN, LI XUB-PING

1991, 9(4):  295-298.  DOI: 10.7517/j.issn.1674-0475.1991.04.295

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The surface state behaviors incorporated into an equivalent circuit of CdSe thin film electrodes have been studied in K₂SO₄ and Fe(CN)₆^3-/^4- solution. Surface state capacitances and resistances were evaluated by analysis of the equivalent circuit impedance in numerical Laplace transformation. The surface state mapping were presented. The results of the similarity of the energies distribution of surface state in both solution indicated that the surface states were bascially associated with the surface nature of CdSe thin film electrodes.

ESR STUDY ON PHOTOGENERATED RADICALS IN AQUEOUS DISPERSIONS OF TUNGSTEN OXIDE CONTAINING SODIUM ACETATE, SODIUM OXALATE AND POTASSIUM TARTRATE

CHEN CI-PING, REN XIN-MIN, LU DAO-HUI, ZHANG YONG-KANG

1991, 9(4):  299-303.  DOI: 10.7517/j.issn.1674-0475.1991.04.299

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The free radical intermediates produced under the illumination of aqueous dispersions of tungten oxide were detected by ESR combined with the technique of spin trapping.When solutions contained sodium acetate were irradiated, the ·CH₃ radical was detected. Whereas in systems containing sodium oxalate the ·CO₂^- radical was obse-rved. In systems containing potassium tartrate, the ·OH, ·CO₂^- and -OOCCOHCH-OHCOO^- radicals were identified.Experiments showed that irradiation of aqueous WO₃ dispersions gives rise to the formation of ·OH radicals. If appropriate substances are present, various other radicals can be generated as well. These are produced either by reaction with the ·OH radicals, or direct transfer of charge from the bands of the semiconducting material.

STUDY ON THE CONCURRENT RADICAL-CATIONIC PHOTOPOLYMERIZATION HYBRID SYSTEM OF ACRYLATE/EPOXY

CHANG ZHI-YING, LI MIAO-ZHEN, LIN PING, SONG HUAI-HAI, WANG ER-JIAN

1991, 9(4):  304-308.  DOI: 10.7517/j.issn.1674-0475.1991.04.304

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A photoinduced concurrent radical-cationic polymerization hybrid system composed of epoxy resin 618/epoxy resin 6101/acrylate with diphenyliodonium salt as photoinitiator was studied. Under UV irradiation the radical and cationic polymerization was carried out simultaneously. The rate constants of radical and cationic photopolymerization of acrylate and epoxy components were determined by infrared spcctrometry, gelatinfraction and hardness respectively. The results obtained show that the acrylate is more reactive related to epoxy component. Evidently the rate of photocuring increases with increasing degree of epoxy content. Such hybrid systems may provide greatly flexibility in formulating UV-curable compositions toward the goal of achieving desirable properties and application.

AN IMAGING PROCESS WITH MULTI-STAGE AMPLIFICATION BY COPPER PHYSICAL DEVELOPMENT

ZHUANG SI-YONG, Fu YAN-XUN, ZHANG YI-HENG, HAN YONG-LING, REN XIN-MIN, HUANG DE-YIN

1991, 9(4):  309-312.  DOI: 10.7517/j.issn.1674-0475.1991.04.309

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The imaging process with multi-stage amplification by copper physical development was studied with different emulsion coatings: the positive cine film, the negative emulsion coating, the direct positive emulsion coating and radiographic film. The results. showed that the sensitivity of the emulsion layer can be increased significantly by the copper physical development and the amount of coated silver can be greatly reduced. It is extremely interesting, as shown in this work, that a Lith Effect can easily be obtained by the copper physical development. The imaging process with multi-stage amplification can find practical applications in the following cases: i. the enhancement of faint images otherwise would not be detected; ii. the development of photographic materials with extremely low silver content; iii. the reduction of X-ray dosage in medical rediography.