Photonic crystals in biology

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Poster Session, Tuesday, June 15 Theme A1 - B702 Synthesis of Novel Organic Liga nds for Gold Nanoparticles Decoration and Architectures Based on Them Alexander Majouga 1 *, Roman Antipin 1 , Elena Beloglazkina 1 , Renata Ro mashkina 1 , Polina Rudakovskaia 1 ,Nikolay Zyk 1 1 Lomonosov Moscow State University, Chemistry Department, Leninskie Gory 1/3, Moscow, Russia, 119991 Abstract At present time the research on gold nanoparticles is one of the most important topic in chemistry, in life and materials science. This is mostly due to the versatility of these systems: the properties of gold nanoparticles can be used in a high range of applications thanks to the combination of their particular and unusual optical and electronic properties. The multi-scale organization of metal nanoparticles is a key step in their application as macroscopic nanodevices. Well organized nanostructures often display valuable chemical, optical, catalytic, electronic and magnetic properties, that are distinctly different from those of their component parts or those of larger mass. Nowadays our research work is deals with synthesis of new organic sulfur-containing ligands with additional donor atoms and investigation of their adsorption properties on gold surface and gold nanoparticles. At present time numerous sulfurcontaining compounds (such as thiols, disulfides, diaryldisulfides, dithiocarbamates, sulfides and thiourea derivatives) are widely applied for gold nanoparticles modification, but, unfortunately the adsorption of organic ligands involving terminal donor groups hasn’t been developed yet, in spite of the fact that interaction of such nanoparticles with transition metal ions would result in obtaining new nano-hybrid materials on the basis of gold nanoparticles. In addition, compared with pure organic compounds, the metal-ligand complexes provide rich redox, optical and electronic properties, which enable them to be good building blocks for constructing functional hybrids. Synthesis of gold nanoparticles, their properties, principle possibility of 2D and 3D aggregates formation will be concerned in presentation. 07-03-00584), RSC and Nanochemtech Ltd. for financial support of this work. *Corresponding author: majouga@org.chem.msu.ru 6th Nanoscience and Nanotechnology Conference, zmir, 2010 276
Poster Session, Tuesday, June 15 Theme A1 - B702 Study on Absorbance of CdS Thin Films from CBD M. Celalettin Baykul 1 *and Baris Altiokka 2 1 2 Bilecik Vocational School, Bilecik University, Bilecik 11210 Turkey Abstract-Cadmium sulfide (CdS) thin films have been grown on a glass substrate from aqueous solution by the chemical bath deposition (CBD). The films are produced at 80±1°C. The band gaps of CdS thin films were found to be between 2,39 and 2,51 eV. The structural properties and surface morphology of CdS thin films have been studied X-ray diffractometer and Scanning Electron Microscope (SEM). CdS is a promising material because of their applications in optoelectronics, photo catalysts, solar energy conversion, X- ray detectors, nonlinear optical material and as a window material for hetero-junction solar cells because it has usually a high absorption coefficient [1]. The good quality of a thin film solar cell (CdS/CdTe) strongly depends on the crystalline quality and compactness of the CdS layers [2]. Although chemical bath deposition has been used as a technique for preparing films since 1910, utilization of CBD semiconductors in photovoltaic devices is much more recent. It started in 1990 with the integration of CdS buffer layers in combination with sputtered zinc oxide, ZnO, films and led to a new generation of high efficiency solar cells [3]. In this work, CdS thin films were deposited by CBD on glass substrates. The substrates are placed in the bath for different deposition time varying from 10 to 50 min. The chemical baths were consisting of aqueous solutions with total volume of 55mL of CdCl 2 (0,004-0,02M), KOH (0,1-0,5M), NH 4 NO 3 (0,3-1,5M) and CS(NH 2 ) 2 (0,04-0,2M). CdS thin films have been also produced on the same glass substrate by adding another CdS layers. The optical properties of CdS thin films were analyzed using UV/vis spectrometer. Absorbance 1,2 1,0 0,8 0,6 0,4 0,2 0,0 450 500 Wavelenght (nm) 550 Figure 1. Optical absorption spectra of CdS thin films (a) minimal molarities of bath concentration (b) maximal molarities of bath concentration Figure 1 shows the optical absorptions spectra of the CdS thin films that were produced using two different molarities of solution. Figure 2 shows the optical absorption spectra of the CdS thin films according to deposition times. Figure 3 shows the optical absorption spectra of the CdS thin films according to the added CdS layers. The structural properties were studied by XRD. The surface morphologies were performed by Scanning Electron a b Absorbance 1,0 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0,0 400 450 500 Wavelenght (nm) 550 Figure 2. Optical absorption spectra for the deposition times (a) 10 minutes (b) 20 minutes (c) 30 minutes (d) 50 minutes Absorbance 4,0 3,5 3,0 2,5 2,0 1,5 1,0 0,5 0,0 450 470 490 510 530 550 Wavelenght (nm) Figure 3. Optical absorption spectra (a) main layer (b) for additional one CdS layer (c) for additional two CdS layer Microscope. The elemental analysis were performed by Energy Dispersive X-ray spectroscopy Conclusion The Energy band gaps of the CdS thin films are between 2,39 and 2,51 eV, CdS thin films have cubic zincblende structures *Corresponding author: 1Tcbaykul@ogu.edu.tr [1] Vineet Singh and Pratima Chauhan, Journal of Physics and Chemistry of Solids 70 (2009) 1074–1079 [2] S. Soundeswaran at all, Materials Letters 58 (2004) 2381– 2385 [3] J. Herrero at all, Thin Solid Films 361-362 (2000) 28-33 a b c d a b c 6th Nanoscience and Nanotechnology Conference, zmir, 2010 277
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