IMAGING SCIENCE AND PHOTOCHEMISTRY

ROLE OF GOLD IN SULPHUR-PLUS-GOLD SENSITIZED EMULSION Ⅱ. SULPHUR-PLUS-GOLD SENSITIZATION COMPARED WITH GOLD HYPERSENSITIZATION AND GOLD INTENSIFICATION

CHEN CI-PING, WANG WEI-QIN, LIU TUN

1986, 4(1): 1-7. DOI: 10.7517/j.issn.1674-0475.1986.01.1

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A comparison has been made between the sensitometric results obtained from sulphur-sensitized cubic silver bromide emulsions which are latensified and hypersensitized with a gold thiocyanate solution, respectively, and those obtained from sulphur-plus-gold sensitized emulsions. An increase in the speed of sulphur-sensitized emulsion by gold latensification demonstrates the enhancing action of gold on the development of emulsion grains. On the other hand, the effect of sulphur-sensitization plus gold latensification is less pronounced than that of sulphur-plus-gold sensitization, whereas, the effect of sulphur-sensitization plus gold hypersensitization is more pronounced than that of sulphur-plus-gold sensitization. This implies some functions of gold in enhancing latent image formation during exposure.The ionic conductivity of these emulsions are measured by the Dember effect. Kinetic analysis of the signal decay rates shows that there is a decreasing trend in the ionic conductivity of the sulphur-plus-gold sensitized emulsion grains and pseudo-first-order decay parameter as compared with those of the sulphur-sensitized emulsion grains. However, gold hypersensitization obviously decreases the ionic conductivity of the sulphur-sensitized emulsion grains and the pseudo-first-order decay parameter. This supports the view that the hypersensitizing effect arises from the increase in the concentration of silver ions in the grain environmen

A STUDY ON THE ELECTRONIC ENERGY LEVEL AND SPECTRAL SENSITIZATION OF GREEN SENSITIZED DYES

LUO SHI-NENG, SHI JUN-YINO

1986, 4(1): 8-16. DOI: 10.7517/j.issn.1674-0475.1986.01.8

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In this paper the Huckel molecular orbital theory has been applied to calculate ,the electronic energy level of a series of symmetrical and unsymmetrical oxacarbocyainine, benzimidazolooxacarbocyanine and quinoline-thiacyanine dyes. Their excitation energy, polarographic half-wave potential and spectral sensitization on silver halide emulsions were measured. The agreement between the calculated and observed values is proved to be fairly good.

STUDY ON THE PREPARATION, STRUCTURE AND PROPERTIES OF TABULAR SILVER HALIDE CRYSTALS Ⅱ. THE INFLUENCE OF PAg ON THE GRAIN SIZE, ASPECT RATIO,DISTRIBUTION OF IODIDE IONS AND IONIC CONDUCTIVITY OF TABULAR SILVER HALIDE CRYSTALS

WANG SU-E, CUI XUE-FU, CHENG HU-MIN, WU NIAN-ZU

1986, 4(1): 17-20. DOI: 10.7517/j.issn.1674-0475.1986.01.17

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The influence of pAg on the grain size, aspect ratio, distribution of iodide inos and ionic conductivity of tabular silver halide crystals during precipitation is studied. With the increase of pAg value during precipitation, the grain size and aspect ratio of tabular silver halide crystals are all increased and more and more iodide ions transfer from the center to the surface of grains. The surface halogen atomic ratio, I:(Br+I), is determined by X-ray photoelectron spectroscopy. The transfer of iodide ions shows that a recrystallization process occurred in the present double-jet precipitation. The dielectric loss of tabular silver halide emulsions with various pAg values during precipitation is examined. The results indicate that the log f_max peaks are shifted toward low frequency with the increase of the surface content of iodide ions and the grain size. But according to our previous paper the log f_max peaks are shifted to high frequency with the increase of total iodide content of tabular silver halide emulsions. The effect of the surface iodide content of the emulsions on the ionic conductivity of the emulsions is not obvious, because the total iodide content of the emulsions is kept constant. The decrease of log f_max peaks is due to the increase of grain size of the emulsions with pAg values during precipitation.

1,8-DIHYDROXY-3,6-DITHIAOCTANE AS SILVER HALIDE CRYSTAL GROWTH-ACCELERATING AGENT

WANG WEN-SHI, GUAN JIAN-HUA, PENG BI-XIAN

1986, 4(1): 21-25. DOI: 10.7517/j.issn.1674-0475.1986.01.21

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We synthesized 1,8-dihydroxy-3,6-dithiaoctane (DTO) and studied its accelerating effect towards the crystal growth during emulsification and physical ripening and its effect on sensitometric properties of silver halide emulsions.1. Prom UV and NMR spectra it can be seen that the valence bridge -S-CH₂-was formed and the synthesized compound has the following structure: HO-CH₂-CH₂ -S-CH₂-CH₂-S-CH₂-CH₂-OH.2. The electron micrographs demonstrate that in absence of DTO the silver halide grains consist of two different parts: one is fairly large, the other ia quite small. When 0.18-0.35 g/molAgBr of DTO is added, a great change in grain size distribution is taken place. When the amount of DTO is increased to 0.5 g/molAgBr, the small grains disappeared practically, all grains became more homogeneous and the average grain size in Fig. 3(B) is shown to be much larger than that in Pig. 3(A), though the biggest grain in Pig. 3(B) seems smaller than that in Pig. 3(A).3. Sensitometric properties can be seen from table 1. With the increase of the amount of DTO the fog increased step by step, sensitivity increased first, through a plateau, later droped to the original value again. The same case was with the contrast.4. Ionic conductivity can be seen from table 2. The addition of DTO ia characterized by the phenomena and its addition has no effect practially on pBr and pH of the emulsion, which is different from other solvent, such as Br^-, ONS^-, and ammonia. With the increase of the amount of DTO log f_max shifts to the range of lower frequency. The log f_max drops from 5.5 to 4.7. This difference in ionic conductivity may be used partly to account for the sensitometric property change of emulsion with the solubiliz-ing effect of DTO.

A STUDY OF HYPERSENSITIZATION BY HYDROGEN SOAKING FOR EMULSION WITH DIFFERENT CHEMICAL SENSITIZERS

FAN SU-YUE, GAO XIU-LIN, TANG DA-GANG, PENG BI-XIAN

1986, 4(1): 26-30. DOI: 10.7517/j.issn.1674-0475.1986.01.26

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In the present paper, a series of experiments of hypersensitization by hydrogen soaking was made for various types of emulsions ripened with different single and combined chemical sensitizers, such as gold(Au), sulphur (S), reduction (R), Au+S, S+ R, Au+R, Au+S+R, and primitive.Comparison has been made of the sensitometric properties, such as surface sensitivity, internal sensitivity, total internal sensitivity, r.m.s. granularity, modulation transfer function (MTF), before and after hypersensitization by hydrogen soaking for all above-mentioned emulsions. It can be seen from our results that the sensitivity of the combined, especially that of Au+R and Au+S+R sensitized emulsions, can be increased 2-3-fold, and the level of low intensity reciprocity failue greatly reduced after hydrogen soaking treatment. Internal sensitivity can be increased too, but in less extent. However the r.m.s. granularity was only changed slightly (10%) and the modulation transfer function remained basically unchanged after hydrogen treatment. All these results further reveal the advantages of hydrogen hypersensitization.

SOME COPOLYMERS WITH MERCURY THIOCARBAZONATE

WENG HUI-JIU, LI ZE-XIN, NI TING, TIEN YU-LIN

1986, 4(1): 31-35. DOI: 10.7517/j.issn.1674-0475.1986.01.31

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Some copolymers of p-methaorylamidophenyl mercuric thiocarbazonate were synthesized. The, photochromic behaviors of these copolymers were tested both under illumination and in dark recover. The effect of their chemical components on photochromic behavior is discussed.

PHOTOPHYSICS OF HYPOCRELUN——INVESTIGATION OF THE ABSORPTION AND EMISSION SPECTRA

LIU JIN-YAO, ZHANG MAN-HUA, AN JING-YI

1986, 4(1): 36-41. DOI: 10.7517/j.issn.1674-0475.1986.01.36

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The photophysics data of hypocrellin, a new photosensitive pigment, were determined, its energy and electronic configuration of the molecular and ionic excited singlet state were also determined through the study of its absorption, emission and polarization spectra.

PHOTOCONDUCTIVE ACTION SPECTRA OF THE EVAPORATED FILM OF αI-PHTHALOCYANINE COPPER

LIUTONG-MINO

1986, 4(1): 42-46. DOI: 10.7517/j.issn.1674-0475.1986.01.42

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The absorption spectrum, photoconductive action spectra of both sandwich and surface cells and Lux-Amere index for the evaporated film of αI-phthalocyanine copper (PcCu) have been measured. The relationship between the shapes of the absorption and photoconductive spectra depends on the ratio of the photocarriers recombination rate in the surface and the bulk of the evaporated film of PcCu. This is because the rate of the surface recombination of the sample is greater than the rate in the bulk; the photoconductive action spectrum of sandwich cell is in reverse in shape to the absorption spectrum in visible region; the photoconductive action spectrum of the surface cell is situated furthermore, between the above-mentioned cases of the two spectra. The sha-pes of the three spectra are similar in the near-infrared region owing to the bulk effect.

THE PHOTOPHYSICAL PROCESSES OF EXCIPLEX FORMATION BETWEEN NAPHTHALENE AND 2,6-DIMETHYL NAPHTHALENE DICARBOXYLATE

CHEN SHANG-XIAN, NIU ER-PING

1986, 4(1): 47-51. DOI: 10.7517/j.issn.1674-0475.1986.01.47

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In this paper, the formation of exciplex between 2,6-dimethyl naphthalene dicar-boxylate and naphthalene was demonstrated by time-resolved fluorescence spectra. The elementary rate constants of the photophysieal processes were calculated by fluorescence spectra measured at steady-state condition. The relationship between the structure and the rate constant has been discussed.

STUDY ON PHYSICO-CHEMICAL PROPERTIES OF THYMINE DIMER AS A PHOTOPRODUCT GENERATED BY UV LIGHT

MA YU-QIN, YU MING-ZHU, SONG XUE-LING

1986, 4(1): 52-57. DOI: 10.7517/j.issn.1674-0475.1986.01.52

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The paper has described the rapid conversion of a low absorbing thymine dimer in the frozen aqueous solution of thymine by UY radiation. Thymine dimer has been isolated and identified and its properties of photochemistry and photobiology have been studied. The experiment results show that the staibility of thymine dimer is influenced by Ag⁺, Fe²⁺, Cu²⁺ and EB dye and the transformation between thymine dimer and thymine depends on the type and the concentration of metal ions.

A STUDY ON INTERACTION OF 9-P-SUBSTITUTED BENZYLIDENE FLUORENES WITH ELECTRONACCEPTORS

WANG XING-GUO, JIANG ZHI-QIN

1986, 4(1): 58-61. DOI: 10.7517/j.issn.1674-0475.1986.01.58

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The charge transfer complexes (CTC) of 9-p-substituted benzylidene fluorenes (1= p-H, 2=p-Cl, 3=p-MeO) and the electron acceptors, chloranil(TCPQ) and 7,7,8,8-tetracyanoquinonedimethane(TCNQ), were studied. The new absorption peaks attributed to the formation of CTC were observed in the visible region(λ=494-586 nm) by UV spectroscopy. Based on the Bensi-Hildebrand equation, the stability equilibrium constants for the six CTC were determined. The results show that the stability of the CTC increases with the increasing of the electron-donating ability of p-substituente in the benzene ring of the 9-p-substituted benzylidene fluorenes.

1986, 4(1): 62-62. DOI: 10.7517/j.issn.1674-0475.1986.01.62

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