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CONTENTS
Volume 1, Number 2, June 2013
 

Abstract
A simple chemical precipitation technique is reported for the synthesis of a hybrid nanostructure of single-wall carbon nanotubes (SWCNT) and titania (TiO2) nanocrystals of average size 5 nm, which may be useful as a prominent photocatalytic material with improved functionality. The synthesized hybrid structure has been characterized by transmission electron microscopy (HRTEM), energy-dispersive X-ray analysis (EDAX), powder X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. It is clearly revealed that nearly monodispersed titania nanocrystals (anatase phase) of average size 5 nm decorate the surfaces of SWCNT bundles. The UV-vis absorption study shows a blue shift of 16 nm in the absorbance peak position of the composite material compared to the unmodified SWCNTs. The photoluminescence study shows a violet-blue emission in the range of 325-500 nm with a peak emission at 400 nm. The low temperature electrical transport property of the synthesized nanomaterial has been studied between 77-300 K. The DC conductivity shows semiconductor-like characteristics with conductivity increasing sharply with temperature in the range of 175-300 K. Such nanocomposites may find wide applications as improved photocatalyst due to transfer of photo-ejected electrons from TiO2 to SWCNT, thus reducing recombination, with the SWCNT scaffold providing a firm and better positioning of the catalytic material.

Key Words
SWCNT; titania; photoluminescence; DC conductivity; photocatalytic material

Address
Rima Paul: Acharya Prafulla Chandra College, Kolkata- 700131, India
Pathik Kumbhakar: Nanoscience Laboratory, Department of Physics, National Institute of Technology Durgapur,
Durgapur-713209, West Bengal, India
Apurba K. Mitra:National Institute of Technology, Durgapur - 713209, India

Abstract
The synthesis of semiconductor nanoparticles is a growing research area due to the prospective applications for the development of novel technologies. In this paper we have reported the biosynthesis of Cadmium sulfide nanoparticles (CdSNPs) by reduction of cadmium sulphate solution, using the bacteria of Serratia nematodiphila. The process for the synthesis of CdS nanoparticles is fast, novel and ecofriently. Formation of the CdS nanoparticles was confirmed by surface Plasmon spectra using UV-Vis spectrophotometer and absorbance strong peak at 420 nm. The morphology of crystalline phase of nanoparticles was determined from Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy and X-ray diffraction (XRD) spectra. The average size of CdS nanoparticles was in the range of 12 nm and the observed morphology was spherical. The results indicated that the proteins, which contain amine groups, played a reducing and controlling responsibility during the formation of CdS nanoparticles in the colloidal solution. Antibacterial activity against some bacteria such as Bacillus subtilis, Klebsiella planticola. CdS nanoparticles exhibiting good bactericidal activity.

Key Words
biosynthesis; cadmium sulfide; semiconductor nanoparticles; SEM; UV-vis spectrophotometer; antibacterial activity

Address
C. Malarkodi, S. Rajeshkumar, K. Paulkumar, G. Gnana Jobitha, M. Vanaja and G. Annadurai: Environmental Nanotechnology Division, Sri Paramakalyani Centre for Environmental Sciences Manonmaniam Sundaranar University, Alwarkurichi – 627 412, Tamil Nadu, India

Abstract
An ultrasonic-mediated assisted stepwise method has been developed for depositing transparent ZnO films from aqueous solution. Rinsing in low ethylene glycol temperature was easy to produce intermediate phase of Zn(OH)2, rinsing in 120oC ethylene glycol was observed the diffraction peak of intermediate Zn(OH)2 in early report, the rinsing temperature plays an important role in the process of Zn(OH)2 phase transformed to ZnO, high rinsing temperature actually improved the intermediate phase. However, the effect of rinsing on the intermediate phase is yet to be understood clearly. The effect of different rinsing procedures, involving either of or a combination of successive ionic layer adsorption and reaction (SILAR) and ultrasonic-assisted rinsing, prior to hydrolysis in ethylene glycol was investigated to deposit ZnO thin films. Ultrasonic-assisted rinsing process before hydrolysis in ethylene glycol was found to improve the occurrence Zn(OH)2 in ZnO thin films. In the zinc complex ([ Zn(NH3)4]2+) solution, excess ([ Zn(NH3)4]2+) absorbed in glass substrate transformed incompletely to ZnO and exist as Zn(OH)2 phase in thin films. In films deposited at low temperature, rinsing procedure is applied to improve excess Zn(OH)2 and obtain smoother transparent thin films.

Key Words
SILAR; ZnO thin films; ethylene glycol

Address
Pay-Yu Lee, Sheng-Po Chang and Shoou-Jinn Chang: Institute of Microelectronics and Department of Electrical Engineering, National Cheng Kung University, 70101 Taiwan

Abstract
We report dry thermal development of negative resist polystyrene with low molecular weight. When developed on a hotplate at 350oC for 30 min, polystyrene showed reasonable high contrast and resolution (30 nm half-pitch), but low sensitivity. Resist sensitivity was greatly improved at lower development temperatures, though at the cost of reduced contrast. In addition, we observed the thickness reduction due to thermal development was higher for larger remaining film thickness, implying the thermal development process is not just a surface process and the more volatile chains below the top surface may diffuse to the surface and get evaporated.

Key Words
electron beam lithography; resist development; polystyrene; nanostructure

Address
Celal Con, Arwa Saud Abbas, Mustafa Yavuz and Bo Cui: Waterloo Institute for Nanotechnology (WIN), University of Waterloo, 200 University Avenue West, Waterloo, Ontario, N2L 3G1, Canada

Abstract
Surface-enhanced Raman scattering (SERS) effect deals with the enhancement of the Raman scattering intensity by molecules in the presence of a nanostructured metallic surface. The first observation of surface-enhanced Raman spectra was in 1974, when Fleischmann and his group at the University of Southampton, reported the first high-quality Raman spectra of monolayer-adsorbed pyridine on an electrochemically roughened Ag electrode surface. Over the last thirty years, it has developed into a versatile spectroscopic and analytical technique due to the rapid and explosive progress of nanoscience and nanotechnology. This review article describes the recent development in field of surface-enhanced Raman scattering research, especially fabrication of various SERS active substrates, mechanism of SERS effect and its various applications in both surface sciences and analytical sciences.

Key Words
Surface-enhanced Raman scattering; Raman scattering cross section; nanoscience; nanostructured metal; nanoparticle; anisotropic; tip-enhanced Raman scattering

Address
Ujjal Kumar Sur: Department of Chemistry, Behala College, Kolkata-700060, West Bengal, India


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