IMAGING SCIENCE AND PHOTOCHEMISTRY

Preparation and Optical Properties of A Surface Modified CdTe Quantum Dots

XU Shi-chao, YAO Cui-cui, ZHANG Ji-mei, DAI Zhao, SUN Bo, ZHENG Guo, HAN Qing, HU Fei, ZHOU Hong-ming

2009, 27(3): 161-167. DOI: 10.7517/j.issn.1674-0475.2009.03.161

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The well-dispersed CdTe quantum dots(QDs) with high fluorescence were synthesized in aqueous phase via thioglycolic acid(TGA) as stabilizer and surface modifier.The optimum conditions to prepare CdTe QDs were investigated,and the resulting CdTe QDs were characterized with ultra-violet spectrophotometer,fluorescence spectrophotometer,and transmission electronic microscope,respectively.The results indicated that the optical properties of synthesized CdTe QDs were obviously dependent on the conditions of refluxing-time,mol ratio of n(Cd²⁺):n(HTe^-),concentration of reactant,amount of TGA,and the pH value of reaction system.The CdTe QDs with size of 5 nm in diameter were achieved when refluxing-time was 2 h,and which showed ideal optical properties of high photo-stability and narrow width of emission peak.

Preparation,Characterization of Novel Silver 2-Mercaptobenzimidazole/Silver Stearate(AgMBM/AgSt) and Its Imaging Property in PTG Materials

LIN Hai-li, CAO Jing

2009, 27(3): 168-174. DOI: 10.7517/j.issn.1674-0475.2009.03.168

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A novel composite grain silver 2-mercaptobenzimidazole/silver stearate(AgMBM/AgSt) was synthesized by using silver stearate(AgSt) as substrate and 2-mercaptobenzimidazole(MBM) as modifier.The microstructure,morphology,crystal form and thermal behavior of AgMBM/AgSt were respectively measured by FTIR,TEM,XRD and TG-DSC.The imaging property of AgMBM/AgSt in photothermographic materials was also investigated.The results showed that AgMBM/AgSt was composed of substrate AgSt with surface supported AgMBM particles.Compared to AgSt,new thermal transition peak was appeared near 80 ℃ as well as low thermal decomposition temperature was achieved for AgMBM/AgSt.When AgMBM/AgSt was applied as silver source in photothermographic materials,the thermal development density of image increased significantly but fog was still kept low.

Sensitization on Tabular Silver Iodine Bromide Emulsion Doped with Oxalate

MA Wang-jing, LI Zhi, SHI Yao, ZHANG Guang-hui, CAO Na, YANG Xin-min

2009, 27(3): 175-181. DOI: 10.7517/j.issn.1674-0475.2009.03.175

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In the emulsifying process of AgBrI microcrystals in the double-jet apparatus controlled by a microcomputer,a certain amount of oxalate salt was injected at specific time and pAg into a reactor to prepare tabular AgBrI grain emulsions in which oxalate ions were doped at subsurface of AgBrI microcrystals.The observation results from the whole experiments and sensitometric results from these emulsions showed: 1) that the sensitivities(Sd) of oxalate-doped emulsions,relative to those(S0) of the corresponding undoped ones as the controlled,regardless of whether it is sensitized chemically and spectrally,were remarkably increased(Sd/S0≥1.5);2) That fog level of oxalate-doped emulsions,regardless of whether it is primitive or sensitized chemically and spectrally,were kept low.

Study on the Effect of Emulsifiers on the Polymerization of Organosilicon-Acrylate Core-Shell Emulsion Using Fluorescence Probe Technique

GAN Meng-yu, LI Xiao-mei, MA Li, PAN Deng

2009, 27(3): 182-189. DOI: 10.7517/j.issn.1674-0475.2009.03.182

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The critical micelle concentration(CMC) of sodium dodecyl sulfate(SDS),alklphenol ethoxylates(OP-10) and composite emulsifiers were determined using fluorescence probe technique.The polymerization of organosilion-acrylate core-shell emulsion was studied by using this technique for the first time.The effect of emulsifier’s micellization in the polymerization of organosilion-acrylate core-shell emulsion was discussed by the I₁/I₃ values of pyrene and the variation of polarity of micelle micro-environment and emulsion polymerization mechanism.It is suggested that the fluorescence probe(pyrene) technique can be used to study the polymerization process of organosilion-acrylate core-shell emulsion and the determination of optimal emulsifier ratio.The properties of the emulsion were characterized by particle size analysis、transmission electron microscope(TEM).

Preparation of Organic Nanowires via Solvent Exchange Method

ZHANG Cheng-yi, WANG Zhong-liang, YANG Jun, WANG Jing, ZHANG Xiu-juan, ZHANG Xiao-hong

2009, 27(3): 190-197. DOI: 10.7517/j.issn.1674-0475.2009.03.190

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One dimensional organic nanostructures were prepared via solvent exchange method and characterized by SEM,TEM and ED.The growth process of the nanowires was also analyzed and discussed.Their spectral properties were researched by UV-vis absorption and fluorescence spectrometers.The results showed that optical properties of molecular aggregates were strongly dependent on the morphology and size of the organic nanostructures.They performed distinct optical properties different from their solution and bulk materials.

Preparation of(I₂)_n Encapsulation Inside TiO₂ and Photocatalytic Degradation of Phenol

DENG Pei-chang, WANG Hai-zeng, FAN Li-xia, SUN Bao-wei

2009, 27(3): 198-206. DOI: 10.7517/j.issn.1674-0475.2009.03.198

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A simple method for preparing highly visible-light photocatalytic activity and stability nanocrystalline (I₂)_n encapsulation inside TiO₂(I₂/TiO₂) powders was developed by a mild hydrothermal route.The as-prepared TiO₂ powders were characterized by X-ray diffraction(XRD),UV-vis diffuse reflectance spectra(DRS) and transmission electron microscopy (TEM).XRD and TEM measurement revealed that HIO₃ and I₂ existed in I₂/TiO₂,the size of I₂/TiO₂ was about 45.0 nm.I₂/TiO₂ exhibited obvious a strong absorption in the range of wavelengths from 384 to 700 nm.The formation process of I₂/TiO₂ and a possible mechanism for the photocatalysis on I₂/TiO₂ under visible light were proposed.Photocatalytic activity test by degradation of phenol,I₂/TiO₂ showed much better photocatalytic activity than P25. The conditions of degradation of phenol were optimized as follows: full-spectrum light illumination,quantity of catalysts is 0.5 g/L,initial concentration of phenol is 10 mg/L,the pH of solution is 3.2.

Gel-Network Controlled Synthesis of ZnO Nanoparticles and Their Photocatalytic Activities

WANG Ying-ling, XIE You-hai, LIU Guo-guang, ZHOU Jian-guo, ZHOU Qing-xiang

2009, 27(3): 207-214. DOI: 10.7517/j.issn.1674-0475.2009.03.207

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ZnO nanoparticles have been prepared by means of a novel gel-network controlled synthesis method using gelatin as a template at lower temperature condition.The products were characterized by using TG-DTA,XRD,TEM,BET,UV-Vis and HPLC techniques.The products appeared to be regularly spherical or elliptical and their sizes range from 20 to 40 nm.The average particle size increased with increasing calcining temperature,and decreased with increasing gelatin concentration.Furthermore,photodegradation of Rhodamine B in aqueous solution was also investigated by using the ZnO nanopowders as the photocatalyst.It was found that the product(13% gelatin concentration) calcinated at 350 ℃ for 2 h nearly induced 99.9% degradation of Rhodamine B in 1 h.

Preparation and Photocatalytic Activity of Heteropoly Acids/Polyvinyl Alcohol Thin Films

GAN Yu, XU Yan-jun, LIU Xia

2009, 27(3): 215-224. DOI: 10.7517/j.issn.1674-0475.2009.03.215

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The polyoxometalates K₆SiM(H₂O)W₁₁O₃₉(M=Co、Ni、Cu)(SiMW₁₁) were synthesized and a series of tungstosilicate acid/polyvinyl alcohol(SiW₁₂/PVA) and SiMW₁₁/polyvinyl alcohol(SiMW₁₁/PVA) composite films were prepared.The results indicated that the original Keggin structure of the SiW₁₂ and SiMW₁₁ remained intact on the films.The photocatalytic activity of the POM/PVA composite films was tested via the degradation of methyl orange(MO) under irradiation of the high pressure mercury lamp.It was observed that the amount of polyoxometalates in the films had important effects on the photocatalytic activity and the ability of photodecolorization is according to the following order: SiW₁₂/PVA>SiCoW₁₁/PVA>SiNiW₁₁/PVA>SiCuW₁₁/PVA.Meanwhile,it is easy to separate and recover the POM/PVA film from the reaction system.

Progress in Research of Preparation of Loaded Nano-CdS and H₂ Production by Photocatalytic Decomposition of Water

CAO Ying, BAI Xue-feng

2009, 27(3): 225-232. DOI: 10.7517/j.issn.1674-0475.2009.03.225

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Cadmium sulfide(CdS),which is a kind of visiblelight-response semiconductor catalyst with the band gap energy of 2.4 eV,is paid extensive attention in the field of photocatalytic reaction.The pure CdS is of low photocatalytic efficiency and easily photocorroded to lead to decrease its photocatalytic activity,which limit its application in the aqueous solution.It has been improved media for catalytic activity & stability of CdS semiconductor catalyst to load nano-CdS on the carriers with large specific surface area & easy exchange which prevent charger recombination.In this paper,preparation of nano-CdS loaded on SiO₂,Al₂O₃,MgO,zeolite,macromolecular materials & layered oxides and their applications in H₂ production of photocatalytic decomposition of water are summarized.

Research on Veracity of Cross-Media Color Reproduction Based on WCS Color Management

WANG Li-li, LIU Zhen

2009, 27(3): 233-238. DOI: 10.7517/j.issn.1674-0475.2009.03.233

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The Microsoft Windows Vista operating system provides WCS(Windows Color System) color manage system,mapping between device color space and standard color space has been using measurement-based device model profile which combined with relevant device model.CIECAM02 color appearance model has been adopted in WCS as color translation space,so that color vision attribute of different vision condition could be forecasted.On the basic of researching on characteristic and work flow of WCS color management which developed by Microsoft and Canon company,according to WCS device model profile scheme and measurement data of display,using XML format to write a device model profile,by designing an experiment method of using display to simulate color cross-media transmission,the result of cross-media color transmission has been evaluated directly;the result of comparing images which separately output by ICC color management system and WCS color management system has further confirmed the strongpoint of WCS color management system in color real-time translation and cross-media reproduction.This paper’s research result makes certain guide sense on implementing high quality color reproduction with WCS color management system.

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