8 research outputs found
Spéciation du technétium en milieu acide (effet des rayonnements a)
Ce projet s inscrit dans le cadre d une étude fondamentale sur la spéciation du technétium en milieu fortement acide. Le comportement de Tc(VII) en milieu HTFMS a été étudié en absence et en présence d irradiation a. Dans ces deux conditions différentes, les résultats spectrophotométriques de réduction de Tc (VII) obtenus pour les mélanges HTFMS-xH O sont similaires. L analyse par SAX indique la formation d un dimÚre cyclique de Tc(IV) complexé aux ligands triflates et formulé Tc O (CF SO ) (H O) . Ce composé est linéarisé en TcIV-O-TcIV quand la concentration de HTFMS augmente. Dans HTFMS à +98% (CHTFMS=11,15 M), le Tc(VII) protoné, de formule TcO (OH)(H O) , stabilisé en absence de rayonnements ionisants externes est réduit en Tc(V) sous irradiation a. La caractérisation structurale par la spectroscopie EXAFS sur la base des calculs DFT suggÚre la formation d un complexe monomÚre de Tc(V) avec les ligands triflates. Les deux composés [OTc(F CSO ) (H O) ] et [OTc(F CSO ) (OH) ] ont été proposées. En milieu H SO concentré (CH SO >= 12 M), des expériences de radiolyse a de Tc(VII) ont été menées afin de pouvoir comparer le comportement radiolytique de Tc(VII) dans les deux milieux apparentés HTFMS et H SO . Les études XANES montrent que la réduction radiolytique de Tc(VII) contribue à la formation d un mélange de Tc(V) et Tc(VII) dans H SO 13 M et à Tc(V) à 18 M en H SO . L analyse des spectres EXAFS indique la formation de complexes monomÚres [TcO(HSO ) (H O) ] et [TcO(HSO ) (H O)(OH)] en milieu H SO 13 M et des espÚces [Tc(HSO ) (SO )(H O)] et [Tc(HSO ) (SO )(OH)] .This project is part of the fundamental study of technetium speciation in highly acidic medium. The behaviour of technetium in HTFMS was carried out in the absence then in the presence of a irradiation. Given these two different conditions, spectrophotometric results of Tc(VII) reduction are similar. XAS analysis indicates the formation of a cyclic dimer of Tc(IV) complexed to triflate ligands and formulated asTc O (CF SO ) (H O) . This compound is linearized to TcIV-O-TcIV with the increase of HTFMS concentration. At high concentration of HTFMS +98% (11.15 M), the protonated species TcO (OH)(H O) which is formed in the absence of external ionizing radiations, is reduced to the V oxidation state under a irradiation. Structural characterization by EXAFS spectroscopy and DFT calculations suggests the formation of monomer species of Tc(V)-triflate complexes where [OTc(F CSO ) (H O) ] and [OTc(F CSO ) (OH) ] compounds were proposed. In concentrated H SO (CH SO >= 12 M), a-radiolysis experiments of Tc(VII) were performed in order to compare the radiolytic behaviour of Tc(VII) in both comparable media HTFMS and H SO . XANES studies show that radiolytic reduction of Tc(VII) leads to the formation of Tc(V)-Tc(VII) mixture in H SO 13 M and just Tc(V) in 18 M of H SO . The analysis of EXAFS spectra is consistent with the formation of [TcO(HSO ) (H O) ] and [TcO(HSO ) (H2O)(OH)] monomer complexes in H SO 13 M and [Tc(HSO ) (SO )(H O)] and [Tc(HSO ) (SO )(OH)] species at 18 M of H SO .NANTES-ENS Mines (441092314) / SudocSudocFranceF
Speciation of technetium in acidic media : effect of α radiations
Ce projet sâinscrit dans le cadre dâune Ă©tude fondamentale sur la spĂ©ciation du technĂ©tium en milieu fortement acide. Le comportement de Tc(VII) en milieu HTFMS a Ă©tĂ© Ă©tudiĂ© en absence et en prĂ©sence dâirradiation α. Dans ces deux conditions diffĂ©rentes, les rĂ©sultats spectrophotomĂ©triques de rĂ©duction de Tc (VII) obtenus pour les mĂ©langes HTFMS-xHâO sont similaires. Lâanalyse par SAX indique la formation dâun dimĂšre cyclique de Tc(IV) complexĂ© aux ligands triflates et formulĂ© TcâOâ(CFâSOâ)â(HâO)â. Ce composĂ© est linĂ©arisĂ© en TcIV-O-TcIV quand la concentration de HTFMS augmente. Dans HTFMS Ă +98% (CHTFMS=11,15 M), le Tc(VII) protonĂ©, de formule TcOâ(OH)(HâO)â, stabilisĂ© en absence de rayonnements ionisants externes est rĂ©duit en Tc(V) sous irradiation α. La caractĂ©risation structurale par la spectroscopie EXAFS sur la base des calculs DFT suggĂšre la formation dâun complexe monomĂšre de Tc(V) avec les ligands triflates. Les deux composĂ©s [OTc(FâCSOâ)â(HâO)â]âș et [OTc(FâCSOâ)â(OH)â]â» ont Ă©tĂ© proposĂ©es. En milieu HâSOâ concentrĂ© (CHâSOâ â„ 12 M), des expĂ©riences de radiolyse α de Tc(VII) ont Ă©tĂ© menĂ©es afin de pouvoir comparer le comportement radiolytique de Tc(VII) dans les deux milieux apparentĂ©s HTFMS et HâSOâ. Les Ă©tudes XANES montrent que la rĂ©duction radiolytique de Tc(VII) contribue Ă la formation dâun mĂ©lange de Tc(V) et Tc(VII) dans HâSOâ 13 M et Ă Tc(V) Ă 18 M en HâSOâ. Lâanalyse des spectres EXAFS indique la formation de complexes monomĂšres [TcO(HSOâ)â(HâO)â] et [TcO(HSOâ)â(HâO)(OH)]â» en milieu HâSOâ 13 M et des espĂšces [Tc(HSOâ)â(SOâ)(HâO)] et [Tc(HSOâ)â(SOâ)(OH)]â».This project is part of the fundamental study of technetium speciation in highly acidic medium. The behaviour of technetium in HTFMS was carried out in the absence then in the presence of α irradiation. Given these two different conditions, spectrophotometric results of Tc(VII) reduction are similar. XAS analysis indicates the formation of a cyclic dimer of Tc(IV) complexed to triflate ligands and formulated asTcâOâ(CFâSOâ)â(HâO)â. This compound is linearized to TcIV-O-TcIV with the increase of HTFMS concentration. At high concentration of HTFMS +98% (11.15 M), the protonated species TcOâ(OH)(HâO)â which is formed in the absence of external ionizing radiations, is reduced to the V oxidation state under α irradiation. Structural characterization by EXAFS spectroscopy and DFT calculations suggests the formation of monomer species of Tc(V)-triflate complexes where [OTc(FâCSOâ)â(HâO)â]âș and [OTc(FâCSOâ)â(OH)â]â» compounds were proposed. In concentrated HâSOâ (CHâSOâ â„ 12 M), α-radiolysis experiments of Tc(VII) were performed in order to compare the radiolytic behaviour of Tc(VII) in both comparable media HTFMS and HâSOâ. XANES studies show that radiolytic reduction of Tc(VII) leads to the formation of Tc(V)-Tc(VII) mixture in HâSOâ 13 M and just Tc(V) in 18 M of HâSOâ. The analysis of EXAFS spectra is consistent with the formation of [TcO(HSOâ)â(HâO)â] and [TcO(HSOâ)â(H2O)(OH)]â» monomer complexes in HâSOâ 13 M and [Tc(HSOâ)â(SOâ)(HâO)] and [Tc(HSOâ)â(SOâ)(OH)]â» species at 18 M of HâSOâ
Spéciation du technétium en milieu acide : effet des rayonnements α
This project is part of the fundamental study of technetium speciation in highly acidic medium. The behaviour of technetium in HTFMS was carried out in the absence then in the presence of α irradiation. Given these two different conditions, spectrophotometric results of Tc(VII) reduction are similar. XAS analysis indicates the formation of a cyclic dimer of Tc(IV) complexed to triflate ligands and formulated asTcâOâ(CFâSOâ)â(HâO)â. This compound is linearized to TcIV-O-TcIV with the increase of HTFMS concentration. At high concentration of HTFMS +98% (11.15 M), the protonated species TcOâ(OH)(HâO)â which is formed in the absence of external ionizing radiations, is reduced to the V oxidation state under α irradiation. Structural characterization by EXAFS spectroscopy and DFT calculations suggests the formation of monomer species of Tc(V)-triflate complexes where [OTc(FâCSOâ)â(HâO)â]âș and [OTc(FâCSOâ)â(OH)â]â» compounds were proposed. In concentrated HâSOâ (CHâSOâ â„ 12 M), α-radiolysis experiments of Tc(VII) were performed in order to compare the radiolytic behaviour of Tc(VII) in both comparable media HTFMS and HâSOâ. XANES studies show that radiolytic reduction of Tc(VII) leads to the formation of Tc(V)-Tc(VII) mixture in HâSOâ 13 M and just Tc(V) in 18 M of HâSOâ. The analysis of EXAFS spectra is consistent with the formation of [TcO(HSOâ)â(HâO)â] and [TcO(HSOâ)â(H2O)(OH)]â» monomer complexes in HâSOâ 13 M and [Tc(HSOâ)â(SOâ)(HâO)] and [Tc(HSOâ)â(SOâ)(OH)]â» species at 18 M of HâSOâ.Ce projet sâinscrit dans le cadre dâune Ă©tude fondamentale sur la spĂ©ciation du technĂ©tium en milieu fortement acide. Le comportement de Tc(VII) en milieu HTFMS a Ă©tĂ© Ă©tudiĂ© en absence et en prĂ©sence dâirradiation α. Dans ces deux conditions diffĂ©rentes, les rĂ©sultats spectrophotomĂ©triques de rĂ©duction de Tc (VII) obtenus pour les mĂ©langes HTFMS-xHâO sont similaires. Lâanalyse par SAX indique la formation dâun dimĂšre cyclique de Tc(IV) complexĂ© aux ligands triflates et formulĂ© TcâOâ(CFâSOâ)â(HâO)â. Ce composĂ© est linĂ©arisĂ© en TcIV-O-TcIV quand la concentration de HTFMS augmente. Dans HTFMS Ă +98% (CHTFMS=11,15 M), le Tc(VII) protonĂ©, de formule TcOâ(OH)(HâO)â, stabilisĂ© en absence de rayonnements ionisants externes est rĂ©duit en Tc(V) sous irradiation α. La caractĂ©risation structurale par la spectroscopie EXAFS sur la base des calculs DFT suggĂšre la formation dâun complexe monomĂšre de Tc(V) avec les ligands triflates. Les deux composĂ©s [OTc(FâCSOâ)â(HâO)â]âș et [OTc(FâCSOâ)â(OH)â]â» ont Ă©tĂ© proposĂ©es. En milieu HâSOâ concentrĂ© (CHâSOâ â„ 12 M), des expĂ©riences de radiolyse α de Tc(VII) ont Ă©tĂ© menĂ©es afin de pouvoir comparer le comportement radiolytique de Tc(VII) dans les deux milieux apparentĂ©s HTFMS et HâSOâ. Les Ă©tudes XANES montrent que la rĂ©duction radiolytique de Tc(VII) contribue Ă la formation dâun mĂ©lange de Tc(V) et Tc(VII) dans HâSOâ 13 M et Ă Tc(V) Ă 18 M en HâSOâ. Lâanalyse des spectres EXAFS indique la formation de complexes monomĂšres [TcO(HSOâ)â(HâO)â] et [TcO(HSOâ)â(HâO)(OH)]â» en milieu HâSOâ 13 M et des espĂšces [Tc(HSOâ)â(SOâ)(HâO)] et [Tc(HSOâ)â(SOâ)(OH)]â»
Spectrophotometric study of the behaviour of pertechnetate in trifluoromethanesulfonic acid: effect of alpha irradiation on the stability of Tc(VII)
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Importance of radiolytic reactions during high-LET irradiation modalities: LET effect, role of O2 and radiosensitization by nanoparticles
International audienceThis article reviews radiation chemistry processes induced by high-linear energy transfer (LET) radiation. The first part gives a short historical introduction and defines the essential concepts of radiation chemistry. It is aimed at radiobiologists in search of basics in this discipline, to link to their biological observations. Then, special focus is done on LET effect, oxygen effect and nanoparticles as these parameters can influence the success of radiotherapy. The embraced point of view is the one from a chemist as involved molecular reactions in water are detailed and revealed, for example, how dioxygen can be produced in situ during high-LET irradiations, even in anoxic conditions. A step forward can be reached using nanoparticles in conjunction with radiation beams to enhance their effects. The last part of this review is thus devoted to the description of an original approach combining high-LET projectiles (3-MeV α-rays) and gold nanoparticles. Fluorescence microscopy was used to evaluate the formation yield of radicals in anoxic condition via scavenging by AmplifluŸ Red. As with low-LET irradiations, an overproduction of radicals was obtained, encouraging to conduct a broader study and to consider nanoparticles in simulation as an additional source of radicals
Behavior of heptavalent technetium in concentrated triflic acid under alpha-irradiation: technetium-triflate complex characterized by X-ray absorption fine structure spectroscopy and DFT
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