Search results for "germani"

Paramagnetic germanium-related centers induced by energetic radiation in optical fibers and preforms

2009

International audience; We investigated the creation processes of Ge-related paramagnetic point defects in silica fibers and preforms, doped with different amounts of germanium, and X-ray irradiated at several radiation doses. Different paramagnetic defect species, like GeE0, Ge(1) and Ge(2), were revealed by electron paramagnetic resonance measurements and their concentration was studied as a function of the irradiation dose. The comparison with the optical absorption spectra points out the main role of Ge(1) on the optical transmission loss of fibers in the UV region.

Chalcogenide Photonic Crystal Fibers for Near and Middle Infrared Applications

2007

Chalcogenide glasses are based on sulphur, selenium, tellurium and the addition of other elements such as arsenic, germanium, antimony, gallium, etc. Chalcogenide fibers present numerous applications in the IR field, such as telecommunication at 1.55 mum, spectroscopy and military systems in the two atmospherics windows (3-5 mum and 8-12 mum). One of the interests of chalcogenide glasses is to associate high non linear properties with their Infrared transmission from 0.51 mum to 12-18 mum depending on the composition. Indeed, chalcogenide glasses present high third order optical properties, 100 - 1000 times as high as the non linearity of silica glass at 1.55 mum. For many applications, sin…

X-ray irradiation effects on a multistep Ge-doped silica fiber produced using different drawing conditions

2011

International audience; We report an experimental study based on confocal microscopy luminescence (CML) and electron paramagnetic resonance (EPR) measurements to investigate the effects of the X-ray (from 50 krad to 200 Mrad) on three specific multistep Ge doped fibers obtained from the same preform by changing some of the drawing conditions (tension and speed). CML data show that, both before and after the irradiation, Germanium Lone Pair Center (GLPC) concentrations are similarly distributed along the diameters of the three fibers and they are partially reduced by irradiation. The irradiation induces also the Non Bridging Oxygen Hole Center (NBOHC) investigated by CML and other paramagnet…

Evolution of Photo-induced defects in Ge-doped fiber/preform: influence of the drawing

2011

International audience; We have studied the generation mechanisms of two different radiation-induced point defects, the Ge(1) and Ge(2) centers, in a germanosilicate fiber and in its original preform. The samples have been investigated before and after X-ray irradiation using the confocal microscopy luminescence and the electron paramagnetic resonance techniques. Our experimental results show the higher radiation sensitivity of the fiber as compared to the perform and suggest a relation between Ge(1) and Ge(2) generation. To explain our data we have used different models, finding that the destruction probability of the Ge(1) and Ge(2) defects is larger in fiber than in preform, whereas the …

Pouvoirs, église et société dans les royaumes de France, de Bourgogne et de Germanie de 888 aux premières années du XIIe siècle

2008

Capes, agrégation 2009-2010

Synthesis and structural characterisation of germanium(II) halide complexes with neutral N-donor ligands.

2010

The Ge(II) complexes [GeX(2)(L-L)] (L-L = 1,10-phen (X = Cl, Br); L-L = Me(2)N(CH(2))(2)NMe(2), 2,2'-bipy (X = Cl)), [GeX(L-L)][GeX(3)] (L-L = 2,2'-bipy (X = Br); L-L = pmdta (MeN(CH(2)CH(2)NMe(2))(2)) (X = Cl, Br)) have been prepared and their crystal structures determined. The crystal structure of [GeCl(2){Me(2)N(CH(2))(2)NMe(2)}] shows a weakly associated centrosymmetric dimer based upon distorted square-pyramidal coordination at Ge(II) and containing asymmetrically chelating diamine ligands. The structure of [GeCl(2)(2,2'-bipy)] contains a chelating 2,2'-bipy ligand and forms a zig-zag chain polymer via long-range intermolecular Ge...Cl bridging interactions, leading to a very distorted…

‘The Germanic Background’

2017

Improved limits on the lepton-flavor violating decays tau(-) -> l(-)l(+)l(-)

2007

A search for the neutrinoless, lepton-flavor violating decay of the tau lepton into three charged leptons has been performed using 376fb-1 of data collected at an e+e- center-of-mass energy around 10.58 GeV with the BABAR detector at the SLAC PEP-II storage rings. In all six decay modes considered, the numbers of events found in data are compatible with the background expectations. Upper limits on the branching fractions are set in the range (4-8)×10-8 at 90% confidence level. © 2007 The American Physical Society.

Preface

2018

Germanium modified BaTiO3as a promising electroceramics

2016

ABSTRACTThe polycrystalline sample of BaTi0.95Ge0.05O3 was prepared by solid-phase reaction using a conventional method. The morphology of investigated sample was characterised by scanning electron microscopy (SEM). The results allowed to determining the stoichiometry of the material and evaluate their microstructure. High quality samples were investigated, the grains are well shaped without of a glassy phase. The dielectric properties of the BaTi0.95Ge0.05O3 ceramics were determined. The results were compared with these ones obtained for pure BaTiO3. The obtained data indicated that the substitution of Ge+4 ions had an influence on the values of the real (ϵ′) and imaginary (ϵ″) parts of el…