IMAGING SCIENCE AND PHOTOCHEMISTRY

STUDY ON PHYSICAL DEVELOPMENT AND AGGREGATION OF SILVER PARTICLES ON SILVER HALIDE CTP PLATE

ZHOU Shu-yun, HU Xiu-jie, SHENG Li-qin, CHEN Ping

2000, 18(4): 289-296. DOI: 10.7517/j.issn.1674-0475.2000.04.289

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Silver halide CTP(Computer-To-Plate) Plate is based on silver halide diffusion transfer principle. In this paper, the influences on the aggregation of physically developed silver were studied with high resolution SEM(Scan Electronic Microscope). The silver clusters in different exposure areas were observed clearly. The silver particles aggregated more closely in low exposure area which usually showed oleophilic. Different shapes of developed silver, such as spherical, branch like, were obtained when various complexing agents were used. The physical developing process was monitored with a set of one dimensional CCD(Charge Coupled Device). The dynamic curves were employed to explain the aggregations of the developed silver.

PREPARATION AND CHARACTER OF TiO₂·SiO₂/BEADS

ZHANG Xin-rong, ZHAO Meng-yue, CHEN Shi-fu

2000, 18(4): 297-301. DOI: 10.7517/j.issn.1674-0475.2000.04.297

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The preparation of composite photocatalyst TiO₂·SiO₂/beads attached to the hollow glass microbeads using Sol?gel technique was investigated. While the photoactivity was evaluated. The results show that mole ratios of TiO₂·SiO₂/beads have the best value. When mole ratio of composite photocatalyst is 30/70,the best composite photocatalyst produces 2 times active than Degussa P 25 TiO₂. Moreover, the effect of the preparation methods and the preparation conditions and the mole ratios and adsorption of TiO₂·SiO₂/beads and calcination conditions and surface area on composite photocatalyst photoactivity were also studied in this paper.

STUDY OF PHOTOGENERATING ACID SYSTEM OF 4,4’- (N,N-DIMETHYLAMINO) BENZOPHENONE AND DIPHENYLIODONIUM SALT AND APPLICATION TO PRINTING PLATE

GAO Fang, XU Jin-qi, LI Li-dong, FENG Shu, Jing, YANG Yong-yuan

2000, 18(4): 302-307. DOI: 10.7517/j.issn.1674-0475.2000.04.302

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An efficient electron transfer process processded between 4,4’-bis(N,N’-dimethylamino) benzophenone(MK) and diphenyliodonium hexafluorophosphate when they were irradiated by high pressure Hg lamp, and the produced acid can catalyze the cross linking reaction between HMMM and the m cresol resin. Excellent results were obtained in making printing plate using this system. The resolution of the plate can reach 7μm and the halftone dot repetition was 2%. Also, the influence of some factors on the plate was investigated carefully.

SOLVENT EFFECTS AND AGGREGATION ACTION OF NOVEL PYRYLIUM-SQUARYLIUM CYANINE DYES

CHEN Jian-guo, LI Yuan, HUANG De-yin

2000, 18(4): 308-315. DOI: 10.7517/j.issn.1674-0475.2000.04.308

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Solvent effects of five novel pyrylium squarylium cyanine dyes in thirteen different solvents were studied. It was found that the positive solvatochromism of the dyes was dependent on the function f(n,ε) with good linearity. The hydrogen bond effect of the solvents was also discussed. Dimers of the dyes in n propanol/water system were investigated and two different aggregation properties were found. Dimer was also detected in dichloromethane with the aid of APCI Mass spectra.

SENSITIZATION OF SILVER CLUSTERS IN SULFUR SENSITIZATION CENTERS

SHI Yao, XIA Pei-jie, YANG Xin-min, YAO Lin-hui, ZHENG Tong, ZHAO Wen-fang

2000, 18(4): 316-322. DOI: 10.7517/j.issn.1674-0475.2000.04.316

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Redox buffers in the range of certain potentials were adopted to treat both sulfur sensitization centers on the surface of mono dispersed cubic silver bromide and latent image centers formed during exposures in order to examine their respective response curves after bleaching and regeneration of silver clusters. Experimental results confirmed that there were silver clusters in the sulfur sensitization centers, which played an important role in the sulfur sensitization as well as the sensitization efficiency seemed to be related to content of silver. For this reason, it has been proposed that the sulfur sensitization centers consist of silver sulfide clusters and silver clusters, in which these two kinds of clusters may have different functions in the process of latent image formation, but both are advantageous to increase in the efficiency of LI formation.

STUDY ON THE ACID EFFECT OF COPPER (Ⅱ) WITH GELATIN REACTION

TANG Shi-hua

2000, 18(4): 323-328. DOI: 10.7517/j.issn.1674-0475.2000.04.323

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The ratio of chelates of Cu²⁺ with gelatin in pH value range between 8.0 to 13.0 is determined by spectrophotometry. Result shows that the ratio increases with increasing pH value. Because the protons are removed from the gelatin molecule in this pH value range. The gelatin molecule provides many amino groups and carboxyl ions. Therefore the Cu²⁺ is a effective fluorsescence quenching agent due to a strong chelation between Cu²⁺ and gelatin molecule.

CO PHOTOCATALYTIC-OXIDATION ON TiO₂

ZHANG Min, JIN Zhen-sheng, WANG Shou-bin, ZHANG Zhi-jun

2000, 18(4): 329-335. DOI: 10.7517/j.issn.1674-0475.2000.04.329

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The photocatalytic oxidation of CO on the “oxidized” TiO₂ was investigated. No CO photooxidation reaction was observed with UV(λ =365 nm) radiation, but CO photocatalytic oxidation could be carried out with UV(λ =253.7 nm) radiation at room temperature. Referring to the catalytic oxidation mechanism of CO on transition metals, it was explained by: O_2(a)^- obtained by the ionsorption of O₂ on the “oxidized” TiO₂ could not oxidize CO, CO photooxidation reaction only occured when O_(a)^- was produced under UV(λ =253.7 nm) illumination.

DYE-SENSITIZED NANOCRYSTALLINE SOLAR CELL

LI Bin, QIU Yong

2000, 18(4): 336-347. DOI: 10.7517/j.issn.1674-0475.2000.04.336

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The fundamental structure and the principle of the dye sensitized nanocrystalline solar cell are introduced.A summary of nanocrystalline TiO₂ film,dye sensitization and hole transporting materials is also given.

MICROREACTOR-CONTROLLED SELECTIVITY IN ORGANIC PHOTOCHEMICAL REACTIONS

WU Li-zhu, ZHANG Li-ping, LI Hong-ru, YI Xiu-yu, SONG Kai, XU Ming, YUAN Zhen-yu, GUAN Jing-qu, YING Yun-ming, WANG Hong-wei, TONG Zhen-he(TUNG Chen-ho)

2000, 18(4): 348-356. DOI: 10.7517/j.issn.1674-0475.2000.04.348

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Molecular-sieves zeolites, Nafion membranes, low-density polyethylene films and mixed surfactant vesicles have been used as microreactors to control the product selectivity in organic photochemical reactions. The photocycloadditions of diaryl compounds with long flexible chains included in NaY zeolite or low-density polyethylene films yield intramolecular photocyclomers to the exclusion of intermolecular products. The photosensitized oxidation of alkenes included in pentasil zeolite or Nafion membrane or vesicles can be directed selectively towards either the singlet oxygen mediated or the superoxide radical anion mediated products by controlling the status and location of the substrate and sensitizer molecules in the reaction media. Long lived photoinduced charge separation in Ru(bpy)₃²⁺/viologen system at Nafion membrane solution interface was achieved.

RECENT ADVANCE IN PHOTO-FENTON REACTION

XIE Yin-de, CHEN Feng, HE Jian-jun, ZHAO Jin-cai

2000, 18(4): 357-365. DOI: 10.7517/j.issn.1674-0475.2000.04.357

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The photo Fenton oxidation is an effecitve advanced oxidation process (AOP). It is gradually using in the treatment of organic pollutants in wastewater. This paper describes the recent advance in this field including the study of the oxidation mechanism, its ultilization in the environmental treatment and some new modified photo-Fenton methods.

COMPILATION OF A SOFTWARE PACKAGE FOR THE USE IN INSTRUMENT OF PHOTOGRAPHIC IMAGE MICROSTRUCTURE ANALYSIS

XING Jin-yun, PAN Qing

2000, 18(4): 366-372. DOI: 10.7517/j.issn.1674-0475.2000.04.366

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A software package, running in the instrument of photographic image microstructure analysis,was compiled.It can be used to test the quality of photographic materials and value the photographic images.This software package makes the instrument powerful enough to obtain several kinds of information of photographic images.During the measurement it can sample data and calculate,showing the character of simple and high speed.The design principal and the structure of the software were introduced,and the function of the software,measurement method and the results were also discussed in detail in the paper.

2000, 18(4): 373-373. DOI: 10.7517/j.issn.1674-0475.2000.04.373

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