Table of Content

20 August 1984, Volume 2 Issue 3

Previous Issue    Next Issue

A STUDY ON THE DIELECTRIC SPECTRA OF DOPED CUBIC SILVER BROMIDE EMULSIONS Ⅲ.EFFECT OF SULPHUR

CHENG HU-MIN, LU XUE-JIANG

1984, 2(3):  1-7.  DOI: 10.7517/j.issn.1674-0475.1984.03.1

Asbtract ( 659 )   PDF (487KB) ( 1108 )  

References | Related Articles | Metrics

The dielectric spectra of the cubic AgBr emulsions doped with Na₂S₂0₃ and Na₂S have been studied.Sodium thiosulfate which is added into AgBr emulsions acts in two ways.1, On the surface of the AgBr microcrystal, the adsorption of sodium thiosulfate is the primary factor when its concentration is lower than 1×10^-4mol/mol AgBr.In this range, the ionic conductivity of AgBr microcrystal decreases slightly with increasing concentration.The f_max of the dielectric loss curve are shifted slightly to lower frequencies, and Δ(logf_max) depend upon the condition of the AgBr microcrystal surface.2, When the concentration of Na₂S₂0₃ is higher than 1×10^-4mol/mol AgBr, it is getting predominant that the surface of the AgBr microcrystal is corroded by S₂0₃= ions.As a result of corrosion, the surface of the AgBr microcrystal becomes more heterogeneous and the distribution of the relaxation time τ of the interface polarization is broadened relatively.On the other hand, when pAg of the emulsions are increased, f_max of the samples are shifted to higher frequencies.f_max of the samples with Na₂S (<1×10-8 mol/mol AgBr) are shifted slightly to lower frequencies.When the dried samples are heated at 75℃ and 110℃ for 6h respectively, S⁼ ions diffuse slowly into the crystal lattice of AgBr, the ionic conductivity of the AgBr microcrystal increases, f_max of the samples are shifted to higher frequencies.

IODIDE DISTRIBUTION IN PHOTOGRAPHIC GRAINS IN RELATION TO METHOD OF GRAIN PRECIPITATION

WU NIAN-ZU, CHENG HU-MIN, GUI LIN-LIN, TANG YOU-QI, Wu GUI-LAN, ZHAN SHI-RONG, LIU DUN

1984, 2(3):  8-15.  DOI: 10.7517/j.issn.1674-0475.1984.03.8

Asbtract ( 777 )   PDF (522KB) ( 1537 )  

References | Related Articles | Metrics

The iodide distribution in the silver iodobromide grains of a high-speed ammonia-cal emulsion is investigated in relation to the instant of time of iodide uncorporation into the emulsion during double-jet precipitation.The X-ray photoelectron spectro-scopic study confirms the general concept that the earlier the iodide incorporation, the less the possibility for the ions to come out to grain surface, and vice versa.However.as shown by X-ray diffraction analysis, with the shift of the instant of iodide incorporation from the end of the precipitation toward the beginning of the process, there occurs an increasingly narrowing of the diffraction profile of the grains, which implies an increasingly more uniform distribution of the iodide, ions through the grains.This "homogenization effect" in the grains, associated with an early iodide incorporation, is believed to be a consequence of a relatively long recrys’tallization and, hence, redistribution process of the silver iodide or silver iodobromide grains formed at the early stages of precipitation.The iodide-containing grains formed by the end of the precipitation are offered less chance of recrystallization and, therefore, a more uneven distribution of the iodide ions in the grains results.In all cases, the surface layer of the grains shows an iodide content considerably higher than might be expected based on a uniform distribution.One of the reasons for the surface enrichment with iodide ions could be the tendency of the grains for a reduction of the lattice distorsion which would arise to a greater extent with more iodide ions incorporated in the grain bulk.

PHOTO-DISCHARGE PHENOMENA OF SE-BASED PHOTORECEPTOR

ZHANG BANG-TING

1984, 2(3):  16-22.  DOI: 10.7517/j.issn.1674-0475.1984.03.16

Asbtract ( 649 )   PDF (448KB) ( 1227 )  

References | Related Articles | Metrics

Some basic requirements and photo-discharge characteristics of Se-based photore-ceptor and the experimental techniques of photo-discharge are presented in the present paper.An equivalent circuit model of Se-based photoreceptor is proposed with consideration of "Residul Potential".The theoretical calculation is compared with experimental results.Finally, some applications of this model are discussed.

PHOTOINDUCED REDOX REACTIONS SENSITIZED BY METAL PHTHALOCYANINES Ⅲ.PHOTOREDUCTION OF METHYL VIOLOGEN IN MICELLER SOLUTION

ZHOU QING-FU, SHEN SHU-YIN, Xu HUI-JUN

1984, 2(3):  23-27.  DOI: 10.7517/j.issn.1674-0475.1984.03.23

Asbtract ( 772 )   PDF (320KB) ( 1341 )  

References | Related Articles | Metrics

A study of the abilities of zinc phthalocyanines derivatives to photoreduce methyl viologen in the presence of EDTA under anaerobic conditions is reported.The reaction rate was increased by the addition of cationic surfactant and retarded with anionic and non-ionic surfactants.Photoactivity of zinc phthalocyanine strongly depends on the substituent on the phthalocyanine ring.Certain zinc derivatives are demonstrated to be more efficient photosensitizers.A remarkably high quantum yield on photore-duction of methyl viologen is one of the notable characteristics of the zinc phthalocyanine derivatives used in the reaction system.The quantum yield in the case of cation-ic micellar solution containing snbstituted zinc phthalocyanines was estimated to be 0.4 to 0.7 which is much higher than that of unsubstituted zine phthalocyanine.

THE REACTIVITY OF EXCITED STATES OF THE SPIROPYRANS

WU GUO-SHENG, HUANG FU-XING, JIANG LONG-XIANG, Gu HUI-JUAN

1984, 2(3):  28-34.  DOI: 10.7517/j.issn.1674-0475.1984.03.28

Asbtract ( 859 )   PDF (472KB) ( 1428 )  

References | Related Articles | Metrics

The photochemistry of 6’-nitro-1, 3, 3-trimethylindolinobenzopyrylospiran, Ⅰ, and 6’-nitro-1-phenyl-3, 3-dimethylindolinobenzopyrylospiran, Ⅱ, was investigated.Both direct and sensitized photolyses of I afforded the coloured species, the merocyanine, Ⅲ, with quantum yields of 0.42 and 0.32, respectively.Direct irradiation of Ⅱ gave the corresponding merocyanine, Ⅳ, with quantum yield of 0.40, while the quantum efficiency on xanthone sensitization of Ⅱ was determined as 0.58 for the same photoproduct.Undoubtelly, both singlet and triplet were involved in the photocolouration of the spi-ropyrans.These results and the bracketing relationships signified that a considerable fraction of Ⅲ came directly from the excited singlet occured on the direct photolysis of Ⅰ, but 70% of Ⅳ was originated from the excited triplet on the direct photolysis of Ⅱ.The triplet parameters were obtained from the sensitization of biacetyl phosphorescence by Ⅰor Ⅱ at varying biacetyl concentrations.These were:φ_Ⅰ^ISC＝0.11,φ_Ⅱ^ISC＝0.48;³K_Ⅰ^dt＝3×10⁴S^-1,³K_Ⅱ^dt＝9×10⁴S^-1;³K_Ⅰ^r＝0.12×10⁴S^-1,³K_Ⅱ^r＝2.52×10⁴S^-1 Thus, the lower magnitute of ³φ_r^Ⅰ was shown to derive from lower intersystem-crossing quantum yield of Ⅰ and the variation of the triplet life time of Ⅰ and Ⅱ with structure was relatively small.Finally, the electronic energy curves of styrene, a model compound, for twisting of the ethylenie bond were employed to assign that the zwitterion came from the excited singlet had a spiro configuratio and the zwitterion originated from excited triplet had a planar configuration.

THE ALTERNATE PHENOMENON OF THE SUBSTITUENT EFFECT IN THE MOLECULE OF CYANINE DYES

LIANG DE-SHENG, LAI CHU-GEN

1984, 2(3):  35-48.  DOI: 10.7517/j.issn.1674-0475.1984.03.35

Asbtract ( 807 )   PDF (631KB) ( 1174 )  

References | Related Articles | Metrics

In this paper the substituent effect in the electronic absorption spectra of cyanine dyes by means of the homologous linear equation has been studied.Its substituent effect is different from gerneral substituent effect, due to the presence of strong alternate phenomenon in the molecule of cyanine dyes.An empirical formula of wide applicability has been suggested and applied to Tarious types of cyanine dyes, including thiacarbocyanines, thiadicarbocyanines, thiatri-carbocyanines, selenacarbocyanines, selenadicarbocyanines and selenatricarbocyanines etc.and their derivatives.The wavelengths of the electronic absorption maximum have been calculated for more than one hundred compounds of cyanine dyes.The results indicate that about 70% of the total number of the compounds shows a deviation of ≤±5nm, about 25% with a deviation of ±5nm to ±10nm and about 5% with a deviation of greater than ±10nm.

A STUDY ON THE PHOTOELECTROCATALYTIC OXIDATION OF ETHENE: METAL/n-GaP PHOTOANODE

HUAN ZHENG-WEI, ZHUANQ QI-XINQ, CAI QI-BEI

1984, 2(3):  49-55.  DOI: 10.7517/j.issn.1674-0475.1984.03.49

Asbtract ( 701 )   PDF (479KB) ( 1404 )  

References | Related Articles | Metrics

In the present paper, possibility to realize the double purposes of both catalytic oxidation of ethene to useful organic products and concurrent production of hydrogen fuel by means of photoelectrochemical method was investigated, as well as the functions of the metallic films (Au, Ag and Pd plated on the surface of n-GaP semiconductor electrode) in preventing photocorrosion of the electrodes and in catalytic oxidation of ethene.The effects of such factors, as applied bias, pH, solvent, and so on, on the anodic reactions have been studied.Possible mechanisms of the reactions have been tentatively discussed.

THE PHOTOOXIDATION OF AMMONIA

HAN TING-XIN, HE SHI-JIN

1984, 2(3):  56-58.  DOI: 10.7517/j.issn.1674-0475.1984.03.56

Asbtract ( 685 )   PDF (201KB) ( 1070 )  

References | Related Articles | Metrics

The photooxidation of ammonia was studied.The experimental results showed that oxygen can be converted into ozone under UV-irradiation and ammonia can be oxidized into nitric acid by ozone produced.0.88 mg of NO₃^- was produced when 400 ml of 5% NH4OH solution was irradiated by 30 W mercury lamp for 1 h.Under the similar condition 2.6 mg of NO₃^- could be obtained with the addition of absorbent charcoal.

PHOTOGRAPHIC EFFECT OF Sn(Ⅱ) IONS DOPING IN SILVER IODOBROMIDE EMULSION

YUE JUN, YAN TIAN-TANG

1984, 2(3):  59-63.  DOI: 10.7517/j.issn.1674-0475.1984.03.59

Asbtract ( 660 )   PDF (338KB) ( 1072 )  

References | Related Articles | Metrics

Photographic effect of Sn(Ⅱ) ions doping in a silver iodobromide emulsion containing 4.0 mol% of Ⅰ^- was studied.Experimental data showed that photographic speeds increased and fogs decreased for either shorter or longer exposure times when a trace of Sn(Ⅱ) ions, of which contents were from 3.84×10^-3mol% to 3.84×10^-2 mol%, were added in the emulsions during precipitation and physical ripening stage.Low intensity reciprocity failure (LIRF) of the emulsiom, on the other hand, diminished due to the same reason.The influence of the concertration of Sn(Ⅱ) on LIRF was also, studied.

SOME FACTORS AFFECTING THE IMAGE COLOR OF DIAZO FILM

LI SAN-BAO, ZHANG YU-CHUAN, PIAO ZHONG-SHUN, ZHANG MO-JUN

1984, 2(3):  64-68.  DOI: 10.7517/j.issn.1674-0475.1984.03.64

Asbtract ( 703 )   PDF (294KB) ( 1305 )  

References | Related Articles | Metrics

The influence of the main components of diazo film, such as couplers, diazonium compounds and binders, on the color of the dye image was studied.The results showed that the color of the dye image is strongly dependent on the structure of the coupler and the substituents on the aromatic nuclei of the diazonium compound.It was demonstrated that the binder also has certain effect on the color of the dye image.