Table of Content

20 February 1999, Volume 17 Issue 1

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STUDY ON THE SECOND FIXING OF CaWO₄ CORE /AgX SHELL MICROCRYSTAL EMULSION

GUO Xinmin, WANG Su’e

1999, 17(1):  1-6.  DOI: 10.7517/j.issn.1674-0475.1999.01.1

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The capability of EDTA disodium salt(CDTA) solution as a second fixing solution to dissolve CaWO₄ core/AgX shell microcrystal emulsion was studied in this paper. The results showed that EDTA disodium salt (CDTA) solution is available for dissolving CaWO₄ in the range of pH 5~12, CaWO₄ can be fully dissolved. The capability of EDTA disodium salt(CDTA) solution to dissolve CaWO₄ core/AgX shell microcrystal emulsion is affected by temperature, pH value and concentration of EDTA disodium salt(CDTA) solution. In comparison with CDTA, the change of concentration of EDTA disodium salt solution makes a greater effect on the fixing capability of EDTA disodium salt than that of CDTA. Under the same conditions of temperature、concentration and pH value, the complexing speed of EDTA disodium salt solution with CaWO₄ is faster than that of CDTA solution.

THE EFFECT OF HYDROXY-TETRAAZAINDENE ON SENSITIZATION

PENG Weiping, DUAN Peicheng, CHEN Ping, ZHENG Deshui

1999, 17(1):  7-11.  DOI: 10.7517/j.issn.1674-0475.1999.01.7

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This study examined the effect of hydroxy-tetraazaindene (TAI) on the sensitization of silver chloride emulsions sensitized by different dyes, as well as the effect of the adding order and concentration of TAI on the sensitization of silver chloride emulsion. The results indicate that there is a close relationship between the sensitization of emulsions by TAI and the molecular structures of dyes, and the effect was different when the adding order of TAI was changed. It was also discovered that the effect of the adding order of TAI and the spectrally sensitizing dye on the sensitization of silver chloride emulsion varied greatly with the increasing of the concentration of TAI.

THE EFFECTS OF Ag, Pd AND Ag⁺, Pd²⁺ ON PHOTODE GRADATION OF CH₃CHO CATALYZED BY TiO₂

YAO Xiaobin, MA Ying, YAO Jiannian

1999, 17(1):  12-16.  DOI: 10.7517/j.issn.1674-0475.1999.01.12

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Photodegradation of CH₃CHO catalyzed by TiO₂ was accelerated after Ag⁺ or Pd²⁺ was added into TiO₂ aqueous suspension. Under nitrogen, Ag⁺ and Pd²⁺ only acted as electron acceptors to separate electron and hole well, while under oxygen, Ag⁺ and Pd²⁺ not only acted as electron acceptors but also increased H₂O₂ produced by illumination in the suspension. But photocatalytic activity of TiO₂ was only improved under oxygen after surface modification was used. Our results show that the concentration of H₂O₂ in the suspension has great effect on photodegradation of CH₃CHO assisted by TiO₂.

SYNTHESIS AND SPECTRAL CHARACTERIZATION SPECIFICITIES OF MULTIPLEX PERYLENE TETRACARBOXYLIC COMPOUNDS

HUANG Deyin, DUAN Xuehui, LIU Yangang, LAN Minbo

1999, 17(1):  17-24.  DOI: 10.7517/j.issn.1674-0475.1999.01.17

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A series of multiplex perylenetetracarboxylic compounds were synthesized by linking two functional subunits, via an oxo-bridge, to the para position of the phenyl groups of N,N’-diphenyl-3,4,9,10-perylenetetracarboxylic diimide(PTCDI). UV-visible and fluorescence spectra were determined and discussed. Some of these compounds showed a novel spectral behavior: strong UV-visible absorption but weak fluorescence emission. It was suggested that the differences in the fluorescence quantum yield were due to the intramolecular photoinduced electron transfer reactions and charge separations in the PTCDI-electron donor linked multiplex systems. The intramolecular energy transfer resulted in the fluorescence steady state quenching.

THE EFFECT OF THE DIFFERENT PREPARATION CONDITIONS ON THE PHOTOCATALYTIC ACTIVITY OF TiO₂/beads

CHEN Shifu, LIANG Xin, ZHAO Mengyue

1999, 17(1):  25-31.  DOI: 10.7517/j.issn.1674-0475.1999.01.25

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The TiO₂/beads photocatalyst was prepared by the dip-coating technique using the hollow glass microbeads as a supporter and TiO₂/beads were characterized by XRD,SEM and TG-DTA. The effect of the different preparation conditions on the photocatalytic activity of TiO₂/beads was studied. The results showed that the photocatalytic activity of the TiO₂/beads was the highest when heat treatment at 600℃ for 5 h and the anatase phase and the rutile phase equal to 81to19.The transition temperature of samples from amorphous structure to the anatase phase was about 429℃. The photocatalytic activity of the TiO₂/beads was better when the anatase phase and the rutile phase coexist in a certain proportion.

PHOTOSENSITIZATION INITIATION SYSTEM OF ETHYL 7-N,N-DIMETHYLAMINO COUMARINYL-3-FORMATE/DIARYLIODONIUM SALT

HE Yong, ZHOU Wenhui, LI Miaozhen, WANG Erjian

1999, 17(1):  32-37.  DOI: 10.7517/j.issn.1674-0475.1999.01.32

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Photosensitizer ethyl 7-N,N-dimethylamino coumarinyl-3-formate (EDACF) was synthesized in this work. Upon irradiation, an electron transfer reaction occurred between excited EDACF and diaryliodonium salt (OPPIP) following with the photobleaching of EDACF and the photolysis of OPPIP, and the latter could yield the active aryl radical. CT characteristics of EDACF might cause the distinct decrease in rate of electron transfer reaction with the increase of solvent polarity. EDACF/OPPIP system can effectively initiate polymerization of MMA, and the kinetic equation of polymerization is R_p=K[OPPIP]^0.47[EDACF]^0.42[MMA]^0.98.

PHOTOCONTROLLED RELEASE BEHAVIOR OF LIPO SOMES COATED WITH A WATER SOLUBLE COPOLYMER CONTAINING AZOBENZENE GROUPS

SHI Xiangyang, SUN Caomin, WU Shikang

1999, 17(1):  38-44.  DOI: 10.7517/j.issn.1674-0475.1999.01.38

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The copolymer of N-isopropylacrylamide (NIPAM) and acrylamido-azobenzene (AAAB) was synthesized for the study of the effect of the photoisomerization of a water soluble copolymer containing azobenzene groups on the photocontrolled release behavior of liposomes. The release property of small unilamellar vesicles(SUV) coated with the copolymer was studied at 25℃ by using 5(6)-carboxyfluorescein (5(6)-CF) as a water soluble marker. Results showed that under photoirradiation, the release of 5(6)-CF from liposomes coated with the copolymer containing azobenzene groups was remarkably increased and exhibits an obvious photocontrolled release property. This phenomenon was discussed preliminarily.

A STUDY ON THE PHOTOPHYSICAL BEHAVIORS AND PHOTOISOMERIZATION REACTION OF BIS(2-BENZOXADYL)STILBENE

JIANG Yongcai, WU Shikang

1999, 17(1):  45-50.  DOI: 10.7517/j.issn.1674-0475.1999.01.45

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The photophysical behaviors and the photoisomerization reaction of bis(2-benzoxazolyl) stilbene have been studied. The relation of the solvent polarity and the emission spectrum of these compounds were discussed preliminarily. It was found that the introduction of small amount of ethylene glycol in the system, the process of trans-cis photoisomerization was improved where the thermo-recover process was inhibited evidently. It was proposed that this phenomenon is ascribed to the formation of hydrogen bonds between benzoxazolyl groups and the ethylene glycol.

PHOTOSENSITIZED ELECTRON-TRANSFERATION OF XANTHENE DYES AND CdS PREPARED IN REVERSE MICELLES

XIE Puhui, CHEN Jingrong, ZHANG Baowen, CAO Yi

1999, 17(1):  51-60.  DOI: 10.7517/j.issn.1674-0475.1999.01.51

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Various sizes of nanometer CdS were prepared in AOT/isooctane/water reverse micelles. Eosin and Rose Bengal were chosed as probes of CdS,and photoinduced charge interactions between CdS and the above xanthene dyes were studied. The results of irradition experiments and ESR techniques revealed the interaction mechanism of these dyes injecting their excited electron to the valance band of CdS.

PHOTOREDUCTION OF CO₂ IN THE SUSPENSION SYSTEM OF SEMICONDUCTOR CATALYST TiO₂ MODIFIED BY PALLADIUM

XU Yongjun, CHEN Fuming, JIANG Linlin, ZHOU Ding

1999, 17(1):  61-65.  DOI: 10.7517/j.issn.1674-0475.1999.01.61

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The experiment of photoreduction of CO₂ was made in the suspension system of Pd/TiO₂ under the illumination of visible light. The findings from the experiments are: (1) Formic acid is the major product of the photoreduction process and its quantum yield is relatively high; (2) The reaction rate increases with the increase of the illumination intensity as well as the feed flowrate of CO₂. It can also be increased by adding an electron donor to the system and the increasing capacity is in the sequence of Na₂C₂O₄>Na₂SO₃>NaH₂PO₂; (3) The photoreduction process was found to be an opposing reaction by dynamics analysis. A model of reaction mechanism, by which the calculated result consisted well with the experimental one, was proposed.

SYNTHESIS AND STUDY ON DYNAMICS OF AGGREGATION REACTION OF TWO ANIONIC CARBOCYANINE DYES

HUANG Guangtuan, HUANG Deyin, LU Minghu

1999, 17(1):  66-72.  DOI: 10.7517/j.issn.1674-0475.1999.01.66

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Two anionic carbocyanine dyes, 5,5’-bis trifluoromethyl-1,1’-diethyl-3,3’-bis-(3-sulfopropyl) benzimidazolocarbocyanine sodium salt, 1’-ethyl-3,3’-bis-(3-sulfopropyl)-5-chloro-5’-trifluoromethyl-benzimidazolo-oxa-carbocyanine, and their intermediates were synthesized. Their structures have been characterized by infra-red spectroscopy (IR), nuclear magnetic resonance (¹H NMR) and mass spectroscopy (MS). UV vis spectra of these two dyes have been determined in 1,2-dichloroethane. It was found that these two dyes had different behavior of aggregation reaction.Moreover,dynamics of aggregation reaction of these two dyes has been studied.

1999, 17(1):  73-84.  DOI: 10.7517/j.issn.1674-0475.1999.01.73

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1999, 17(1):  85-91.  DOI: 10.7517/j.issn.1674-0475.1999.01.85

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1999, 17(1):  92-95.  DOI: 10.7517/j.issn.1674-0475.1999.01.92

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