Papers by Author: P. Desgardin

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Authors: Laszlo Lizkay, C. Corbel, P. Perez, P. Desgardin, Marie France Barthe, Toshiyuki Ohdaira, Ryoichi Suzuki, P. Crivelli, Ulisse Gendotti, A. Rubbia, M. Etienne, A. Walcarius
Abstract: Positron annihilation gamma energy distribution, lifetime spectroscopy and time-of-flight method were used to study surfactant-templated mesoporous silica films deposited on glass. The lifetime depth profiling was correlated to Doppler broadening and 3γ annihilation fraction measurements to determine the annihilation characteristics inside the films. A set of consistent fingerprints for positronium annihilation, o-Ps reemission into vacuum, and pore size was directly determined. The lifetime measurements were performed in reflection mode with a specially designed lifetime spectrometer mounted on a slow positron beam system. The intensity of the 142 ns vacuum lifetime component was recorded as a function of the energy of the positron beam. In a film with high porosity a reemission efficiency of as high as 40 % was found at low positron energy. Positron lifetime in samples capped by a thin silica layer was used to determine the pore size. The energy of the reemitted o-Ps fraction was measured by a time-of-flight detector, mounted on the same system, allowing determination of both o-Ps re-emission efficiency and energy in the same sample. We demonstrate the potential of the simultaneous use of different positron annihilation techniques in the study of thin porous films.
Authors: X. Kerbiriou, A. Greddé, Marie France Barthe, P. Desgardin, G. Blondiaux
Authors: C.L. Liu, E. Ntsoenzok, Marie France Barthe, P. Desgardin, S. Ashok, A. Vengurlekar, Daniel Alquier, M.O. Ruault
Authors: Marie France Barthe, S. Guilbert, H. Labrim, P. Desgardin, Thierry Sauvage, G. Blondiaux, G. Carlot, P. Garcia, Jean Paul Piron
Authors: D.T. Britton, D. Gxawu, A. Hempel, Marie France Barthe, L. Henry, P. Desgardin, C. Corbel, W. Bauer-Kugelmann, Peter Sperr, Gottfried Kögel, Werner Triftshäuser
Authors: P. Desgardin, L. Liszkay, Marie France Barthe, L. Henry, J. Briaud, M. Saillard, L. Lepolotec, C. Corbel, G. Blondiaux, A. Colder, P. Marie, M. Levalois
Authors: L. Liszkay, K. Havancsák, Marie France Barthe, P. Desgardin, L. Henry, Z. Kajcsos, Gábor Battistig, E. Szilágyi, V.A. Skuratov
Authors: Marie France Barthe, P. Desgardin, L. Henry, C. Corbel, D.T. Britton, Gottfried Kögel, Peter Sperr, Werner Triftshäuser, Patrice Vicente, L. diCioccio
Authors: X. Kerbiriou, Marie France Barthe, S. Esnouf, P. Desgardin, G. Blondiaux, G. Petite
Abstract: In this work we used Positron Annihilation Spectroscopy (PAS) and Electron Paramagnetic Resonance (EPR) to investigate the properties of vacancy defects produced by low energy electron irradiation. N-doped 3C-SiC and 6H-SiC monocrystals have been irradiated with electrons at different energies from 240keV to 900keV. EPR measurements show that Frenkel pairs VSi 3-/Si are created in 6H-SiC when electron irradiation is performed at low energy (240-360 keV). EPR also indicates that the silicon displacement threshold energy is higher in 3C-SiC than in 6HSiC. Moreover, PAS results show that the size and concentration of the vacancy defects decrease when the electron energy decreases for both polytypes. PAS detects vacancy defects in 240keV electron irradiated 3C-SiC, and the detection of the carbon vacancy is proposed.
Authors: P. Desgardin, Marie France Barthe
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