IMAGING SCIENCE AND PHOTOCHEMISTRY

STUDY ON THE CRYSTAL HABIT AND GRAIN SIZE DISTREBUTION OF CONVERSION EMULSION

WAN JING-XIU, PENG YAN-BIN, LI ZHEN-XING, PENG BI-XIAN

1995, 13(1): 1-6. DOI: 10.7517/j.issn.1674-0475.1995.01.1

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It is observed that during the process of converting cubic AgCl emulsion to AgCl Bremulsion,The shape of grains become round gradually, the mean volume of grains increases serveral times and the variation coefficient of grain size distribution tends to decrease. The enlargement of the grain volume can be explained as that besides of Ostwald ripenning the reexsists material transfer between grains accompaning the conversion process,some grains are broken into very small pieces and dissolved very quickly,the material contained in those grains is transfered to the growing grains.

LUMINESCENCE BEHAVIOR OF SUBSTITUTED DISTYRYL PYRAZINE ANALOAUES

LIZE-MIN, WU SHI-KANG

1995, 13(1): 7-15. DOI: 10.7517/j.issn.1674-0475.1995.01.7

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Three Kinds of substituted distyryl pyrazine derivatives were synthesized and characterized in this work.Their photophysical behavior and emission properties were studied.The causes of the strong emission for the aza-stilbene I,II with electron donating substittients and the weak emission for the compound Ⅲ with nitro-group were also discussed.It was considered that the weak proximity effect of compound Ⅲ was enhanced by the introduction of nitro-group which is the main reason bring about the results obtained in this paper.

A STUDY ON THE FLUORESCENCE EMITTING MECHANISM OF 2-PYRAZOLINE

YAN ZHENG-LIN, WU SHI-KANG

1995, 13(1): 16-21. DOI: 10.7517/j.issn.1674-0475.1995.01.16

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In this work,a new type of 2-pyrazoline compound,1,3-diphenyl-4-(p-nitroben-zylidene)-2-pyrazoline(TPP),was synthesized; and the steady-state photophysical behavior at room temperature and lower temperature(77K) of the compound were studied. Results indicate that there are two charge transfer mechanisms in TPP,one is from N1→N2→C3→phenyl group,the other is from N1→N2→C3→C4→p-nitrobenzylidene. When the compound TPP is excited,two charge transfer mechanisms compete with each other,and have different fluorescence emitting conformations.

THE INFLUENCE OF 1-PHENYL-5-MERCAPTOTETRAZOLE ON THE OXIDATION OF p-PHENYLENEDIAMINE WITH Co(Ⅲ)-COMPLEXES CATALYZED BY AU SOL

MO YI-BO, ZHAO WEN-FANG, HU PING, REN XIN-MIN

1995, 13(1): 22-27. DOI: 10.7517/j.issn.1674-0475.1995.01.22

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In this paper,the catalysis of Au sol in the reaction of [Co(NH₃)₅]Cl₃ with P-phenylenediamine(PPD)was studied in the presence of 1-phenyl-5-mercaptoterrazole(PMT).When pH =10.20 at 25℃,it was found that PMT influences the initial reaction rate strongly:PMT restrains the reaction when [PMT].is low,and accelerates the reaction when [PMT]is high. By means of determining the kinetic parameters,the possile mechanism was discussed.It was proposed that the restraining-accelerating effect may be caused by the change of absorption state of PMT on Au sol.It was found that the similar phenomenal so exists when [Co(NH₃)₆]Cl₃ is replaced by [Co(NH₃)₅Cl]Cl₂.

STUDY ON THE AGGREGATION OF PORPHYRIN AND PHTHANLOC-YANINE BEARING OPPOSITELY CHARGED SUBSTITUENTS BY FLUORESCENCE SPECTROSCOPY

MAO HAI-FANG, TIAN HONG-JIAN, XU HUI-JUN

1995, 13(1): 28-34. DOI: 10.7517/j.issn.1674-0475.1995.01.28

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The supramolecular system consisting of a water-soluble meso-tetrakis-[(P-trimethylphenyl)ammonio] porphyrin tetraiodide and a gallium tetrasodium tetrakis(4’-sul-fonato)phthalocyanine was studied by fluorescence spectroscopy. In water solution,mixing of the anionic phthalocyanine with the cationic porphyrin yields heteroaggregate. The results of fluorimetric titrations indicated that the hetero-aggregate in a heterodimer and the formation equilibrium constant of the heterodimer is 1.17×10⁸ L/mol.The value of the for-mation equilibrium constant indicates that the heterodimer is very stable in water solution.No fluorescense emision of the heterodimer was observed.

PHOTOINDUCED SULFONATION OF HYPOCRELLINS——EFFECTS OF REACTION CONDITIONS ON THE PHOTOSULFONATION OF HYPOCRELLIN B

HU YI-ZHEN, AN JING-YI, JIANGLI-JIN

1995, 13(1): 35-41. DOI: 10.7517/j.issn.1674-0475.1995.01.35

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Ⅲumination of a solution contahing hypocrellih B(or A)and Na₂SO₃ leads to the formation of 5 or 8-sulfonated and 5,8-disulfonated hypocrellin B (or A).The photo induced sulfonation of hypocrellins is very susceptible to the changes of reaction conditions such as the concentration of oxygen,pH value of the solution,and polarity of the solvent.In aeratedsolution,the rate of sulfonation is much faster than that in deaerated solution,and some sidereactions(e. g self-sensitized)which are favourable under oxygen can be prevented.The optimum pH value for the sulfonation is pH 7.0～7.7.The rate of the photo-sulfonation declines with the decrease of the polarity of the solvent.strongly polar solventsfacilitate the sulfonation of hypocrellins.

STUDY ON PHOTOVOLTAIC EFFECT OF CHLOROPLAST

HAN YUN-YU, ZHOU RUI-LING, YANG YU-GUO, WANG QING-FAN, RUAN XIAO-LAN

1995, 13(1): 42-47. DOI: 10.7517/j.issn.1674-0475.1995.01.42

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Chloroplast (chlp)solutions were prepared from fresh sphach leaves in the media: dis-tilled water(Ⅰ),0.1mol/l KCl(Ⅱ),0.35mol/l NaCl+0.01mol/l Tris (Ⅲ),0.005mol/lMgCl₂+0.005mol/l EDTA(Ⅳ)and Ⅲ+Ⅳ(Ⅴ).The photovoltaic effect of chlp solutionon SnO₂ optically transparent conductive glass eletrode(OTE) was measured,using Pt,C and SCE as counter electrodes,respectively. The working curves of chlp cells were drawn with an x-y recorder,and from those we got various characteristic parameters of the cells.The power conversion efficiency was above l0^-4%,The absorption spectra of chlp solutions were analyzed and the possible mechanism of photovoltaic effect of chlp and charge transfer was discussed.

PHOTOCATALYTIC ASYMMETRIC SYNTHESIS OF L-α-VALINE FROM3-METHYL-2-OXOBUTANOIC ACID WITH CHIRAL Rh(Ⅱ)COMPLEXES AND POWDERY SEMICONDUCTORS

WANG HAN-HUI, YUJIA-YONG, HUANG JI-PING, CUI GUO-ZHU, YANG SHI-YAN, SUN WEN-HUA, LIU JIN-XIA

1995, 13(1): 48-52. DOI: 10.7517/j.issn.1674-0475.1995.01.48

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Photo catalytic asymmetric synthesis of L-α-valine from 3-methyl-2-oxobutanoic acid has been carried out in up to 64%e.e. in apueous solution of metbanol ammonia with chiral(+)-diop-Rh(Ⅰ)complexes(diop:2,3-o-isopropylidene-2,3-dihydroxy-1,4-bis(diphenyl-phosphino)butane)and semiconductor photocatalysts CdS,Pt/CdS,TiO₂,Pt/TiO₂ irradi-ated 10 h under 500W Xenon lamp.

ENERGY TRANSFER IN R-PHYCOERYTHRIN FROM RED ALGA PROPHYRA YEZOENSIS

WU HUA-JU, ZHANG JIAN-PING, XIA AN-DONG, ZHU JING-CHANG, JIANG LI-JIN

1995, 13(1): 53-60. DOI: 10.7517/j.issn.1674-0475.1995.01.53

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The energy transfer processes ih R-phycoerythrin as well as its α,β,γ,subunits isolated from red alga prophyra yezoensis were studied by absorption, fluorescence spectra and the deconvolution of these spectra.A tentative assignment of“s”and“f”type chromophores in R-PE and α,β,γ subunits was also maken, The“f”type chromophore in β(or γ)subunitis found to be an s-type chromophore in R-PE[(αβ)₆γ], and transfer its energy to the final“f”type chromophores. The results obtained from the fluorescence excitation polarization spectrum of R-PE are in good agreement with the deconvolution results for the energy transfer processes.

THE PHOTOPHYSICAL AND PHOTOGRAPHIC PROPERTIES STUDY OF MULTISTRUCTURE EPITAXIAL TABULAR SILVER HALIDE MICROCRYSYALS

LU TAO, XU YONG-EN, WANG SU-E

1995, 13(1): 61-67. DOI: 10.7517/j.issn.1674-0475.1995.01.61

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A series of unepitaxial and epitaxial multistructure tabular silver halide microcrystals with the same content but different distribution of iodide ions were prepared by double-jet precipitation. The ditribution of iodide ions and the position of epitaxial AgCl in the micro-areas of a single microcrystal were analysed by the means of Scanning Transmissive Electron Microscope(STEM)and X-ray Energy Dispersive Spectrorneter(EDS).It was found that the iodide and chlorine ions are distributed in the different microareas of tabular microcrystals as designed.The photophysical and photographic properties were investigatd,The results showed that the influence of epitaxial AgCl on the property of tabular silver halide microcrystals apparently depends on the multistructure of original tabular iedobromide micrcocrystals. Reasonable structure with high utilizing efficiency of photoelectrons as well as with high original sensitivity has few contribution to enhancing its sensitivity after being epitaxized.On the other hand,there will cause two results after epitaxizing on the emulsion with unreasonable structure:increasing the efficiency of formation of latent image and increasing the dispersion of latent image.

ELECTRO PHOTOGRAPHIC PROPERTIES OF A SINGLE-LAYERED CuPc PHOTORECEPTOR-THE EFFECTS OFε-CuPc CONCENTRATION

PU JIA-LING, ZHANG WEI-MING, FU YI-LIANG

1995, 13(1): 68-73. DOI: 10.7517/j.issn.1674-0475.1995.01.68

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Photoreceptor used in this study was a single-layered ε-CuPc which was prepared bydispersing the photoconducting pigment in a polyester at different concentrations and coatingthe dispersion on aluminum substrate. Results showed that such prepared devices can be usedas positive and negative-charging photoreceptors and the negative-charging yields higher surface potential than positive-charging under identical corona-discharging-voltage,i.e.,V-V_T(V_T is the threshold corona-discharging-voltage).High ε-CuPc concentrations over 40%induced too fast dark-decay.Dark-decay was brought under control by reducing the loadingof ε-CuPc to below 20%,but at the sacrifice of photo decay speed,resulting in higher residualpotential. The loading of ε-CuPc in the range of 30 to 40%was considered most proper.

A STUDY ON PHOTOELECTRIC CONVERSION OF DYE-SENSITIZED TiO₂ MICROPOROUS ELECTRODE

SHEN YAO-CHUN, WANG LIN, LU ZU-HONG, WEI YU, ZHOU QING-FU, MAO HAI-FANG, XU HUI-JUN

1995, 13(1): 74-77. DOI: 10.7517/j.issn.1674-0475.1995.01.74

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The transparent titanium dioxide TiO₂ film of high surface area has been prepared.Atomic force microscope analysis confirms that the film is composed of interconnected particles and pores. Sensitization of TiO₂ microporous electrode with porphyrin molecules extendsthe absorbance of the electrode into visible region. The photoelectric conversion study showsthat the dye-sensitized TiO₂ microporous electrode is attractive in photoelectrochemical conversion of solar energy in the future.

A STUDY ON THE RHODAMINE B DERIVATIVES USED AS PROBE IN SURFACTANT SOLUTIONS

GU XIN-HUA, DAI GUANG-SONG, WU SHI-KANG

1995, 13(1): 78-82. DOI: 10.7517/j.issn.1674-0475.1995.01.78

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In this work,some derivatives of Rhodamine B,in which a long hydrocarbon chain compound is included,were studied.Their flurorescence behaviors in various surfactant solutions were studied carefully.It was found that the long hydrophobic hydrocarbon chain Rhodamine B is favorable to aggregate to dimers in water solution. and the dimer formed is also favorable to dissociate to monomer of Rhodamine B when the critical concentration of micellar formation of surfactant is arrived.Results indicate that the long chain Rhodamine B usedas a fluorescent probe for determination of the properties of microenvironment is more sensitive than that of other Rhodamine B derivatives.

SEMICONDUCTING POLYMER DEVICES:NEW DEVELOPMENTS

YU GANG

1995, 13(1): 83-86. DOI: 10.7517/j.issn.1674-0475.1995.01.83

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Since the discovery of metallic conductivity in doped conjugated polymers (such as in doped polyacetylene),semiconducting properties of undoped conugated polymers have been drawn equal attentions. In additonal to the interests in the nonlinear properites of funda-mental excitations in these materials,possibilities of device applocations (such as solar cells and field -effect transistors) have been investigated in the past decade. However,the perfor-mance of polymer devices developed in early times was far from that of commercial devices made with inorganic materials (which was commonly attributed to the low carrier mobility of these materials),that managers and engineers in device industry dropped their initial in-terests gradually on this type of materials in later 1980' s.

1995, 13(1): 87-88. DOI: 10.7517/j.issn.1674-0475.1995.01.87

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