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Dwivedi R.,Devi Ahilya University | Maurya A.,Dr Hari Singh Gour University | Verma A.,Devi Ahilya University | Prasad R.,Devi Ahilya University | Bartwal K.S.,RRCAT
Journal of Alloys and Compounds | Year: 2011

A simple and fast synthesis of zirconia nanoparticles by microware assisted citrate sol-gel method is reported. The formation of nanoparticles was characterized by performing powder X-ray diffraction (XRD) of the samples calcined at higher temperatures. The physico-chemical characterizations were done employing techniques of Raman spectroscopy and BET surface area measurements. Fourier transform infrared spectroscopy (FTIR) was performed to analyze the band structure and functional groups. High-resolution transmission electron microscopy (HRTEM) was done for analyzing the morphology of nanoparticles and estimating the crystallite sizes. The prepared material was found to have tetragonal symmetry. The average particle sizes were found ranging ∼5-10 nm. Gelation and fast combustion seems to be the reason for smaller particle sizes. © 2011 Elsevier B.V. All rights reserved. Source


Kumar S.,RRCAT | Mukherjee C.,Mechanical and Optical Support Section | Dixit V.K.,Semiconductor Laser Section | Singh S.D.,Semiconductor Laser Section | Jha S.N.,Applied Spectroscopy Division
Applied Surface Science | Year: 2011

Plasmon peaks along with Auger PLVV peak have been observed in the ultraviolet photoelectron spectra (UPSs) of InP after 5 min of sputtering with 0.5 kV Ar+ ions. Plasmon and Auger peaks are not observed in UPS of un-sputtered InP surface with native oxides of In and P. Filled electron energy levels are not observed near the Fermi level from 5 min sputtered InP surface due to increase of ionization potential of nano In clusters. © 2011 Elsevier B.V. All rights reserved. Source


Saini R.K.,Laser RandD | Srivastava A.K.,RRCAT | Gupta P.K.,Laser RandD | Das K.,Laser RandD
Chemical Physics Letters | Year: 2011

Aggregation behaviour of Chitosan and glycol-Chitosan stabilized silver nanoparticles was investigated over the pH range of 3.4-13. With increasing pH, the charge of the particle reduces and approaches zero beyond 6.5 (the pK a of the amino group) inducing aggregation that was confirmed by absorption spectroscopy, hyper-Rayleigh scattering (HRS) and TEM measurements. Interestingly the HRS intensity increased till pH 9.0 ± 2.0 and beyond this it dropped dramatically. This correlated with the formation of centrosymmetric spherical aggregates as evidenced by TEM pictures. The aggregation process was found to be reversible over at least 10 pH cycles by absorption and HRS measurements. © 2011 Elsevier B.V. All rights reserved. Source


Astadjov D.N.,Bulgarian Academy of Science | Nakhe S.V.,RRCAT
Journal of Physics: Conference Series | Year: 2010

CuBr laser beam profile transformations are studied in a beam focusing experiment. A modeling via Fourier transform is also performed with annular beams of simplified flat two-level geometry of near field: bright outer ring with a darker core. The pattern of focal beam profile i.e. far field is calculated and characterized with respect of its intensity structure. As found beam annularity has small effect on far-field intensity pattern. © 2010 IOP Publishing Ltd. Source


Sahani P.K.,RRCAT | Haridas G.,Bhabha Atomic Research Center | Sarkar P.K.,Bhabha Atomic Research Center
Indian Journal of Pure and Applied Physics | Year: 2012

Bremsstrahlung photons followed by photoneutrons are the major radiation hazards in high energy electron accelerators. These neutrons in high energy electron accelerator are produced by Bremsstrahlung photons through photo nuclear reactions. Monte Carlo code FLUKA was used to generate the photoneutron spectra for 20 MeV, 450 MeV and 2.5 GeV electron (electron energies in Indus facility) hitting 4 mm of tungsten target. The total photoneutron yield was calculated from the generated spectrum for different target thicknesses. The results have indicated the isotropic Giant Dipole Resonance (GDR) neutrons dominating the spectra for the above three incident electron energies. The peak energy of the neutron spectra lies between 0.1-1 MeV for these electron energies. The average neutron energy was calculated and found to be 0.82 MeV, 4.09 MeV and 11.6 MeV for 20 MeV, 450 MeV and 2.5 GeV incident electron energy, respectively. The details of the simulation and results are discussed in the paper. Source

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