[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Progress in preparation, processing and applications of polyaniline

Journal of Physics Condensed Matter: Preface

We show that the Raman scattering technique can give complete structural information for one-dimensional systems, such as carbon nanotubes. Resonant confocal micro-Raman spectroscopy of an (n,m) individual single-wall nanotube makes it possible to assign its chirality uniquely by measuring one radial breathing mode frequency omega(RBM) and using the theory of resonant transitions. A unique chirality assignment can be made for both metallic and semiconducting nanotubes of diameter d(t), using the parameters gamma(0) = 2.9 eV and omega(RBM) = 248/d(t). For example, the strong RBM intensity observed at 156 cm(-1) for 785 nm laser excitation is assigned to the (13,10) metallic chiral nanotube on a Si/SiO2 surface.

Structural (n,m) determination of isolated single wall carbon nanotubes by resonant Raman scattering

Polymeric materials with antimicrobial activity

The narrow gap lead chalcogenides and related solid solutions have been the materials of considerable technological importance. Their unusual and unique characteristics make them a preferred subject for solid state research and development. The high quality polycrystalline thin films of PbS have been deposited onto ultra-clean glass substrates by vacuum evaporation technique. The as-deposited films were annealed in vacuum at 350 K. The optical, electrical and structural investigations on PbS thin films have been carried out. The optical band gap and optical constants (absorption coefficient, refractive index and extinction coefficient) of the films were determined by absorbance and transmittance measurements using Fourier transform infrared spectrophotometer. The DC conductivity and activation energy of the films were measured in temperature range 300–380 K. The schottky junction of PbS with indium was made and the barrier height and ideality factor were determined using current–voltage characteristics. The sample quality, crystal structure and lattice parameter of the films were determined from X-ray diffraction pattern.

Characterization of vacuum evaporated PbS thin films

Cadmium sulphide nanoparticles were synthesized by chemical displacement reaction method using cadmium nitrate as cadmium source and ammonium sulphide as sulphur source. The CdS samples are characterized using X-ray diffraction, UV–Vis spectroscopy, FTIR spectroscopy, scanning electron microscopy and impedance spectroscopy. CdS nanoparticles are found to possess cubic structure with the crystallite size ~10 nm. The absorption spectra of synthesized CdS nanoparticles revealed the blue shift in excitonic transitions with respect to CdS bulk material, clearly confirming the formation of nanoparticles. The dielectric properties of CdS nanoparticles are studied in the frequency range 103–107 Hz at room temperature. The dielectric properties of CdS nanoparticles are found to be significantly enhanced specially in the low frequency range due to confinement.

Chemical synthesis of CdS nanoparticles and their optical and dielectric studies

Synthesis and characterization of Se doped polyaniline

The optical band gap and optical constants have been studied as a function of photon energy for a-Ga x Se100–x thin films (where x × 0, 2.5, 5.0, 7.5 and 10.0) in the wavelength region 450–1000 nm. The optical band gap decreases with the increase of Ga concentration in the a-Ga x Se100–x system. The refractive index (n) decreases while the extinction coefficient (k) increases with increasing photon energy. The results are interpreted in terms of concentration of localized states.

M. Zulfequar

Papers

Characterization of vacuum evaporated PbS thin films

Chemical synthesis of CdS nanoparticles and their optical and dielectric studies

Synthesis and characterization of Se doped polyaniline

Optical investigation of a-GaxSe100-x thin films

RF-plasma polymerization and characterization of polyaniline