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Gennevilliers, France

Lejeune A.,Aix - Marseille University | Lejeune A.,Cameca SAS | Cherigier-Kovacic L.,Aix - Marseille University | Doveil F.,Aix - Marseille University
EPL | Year: 2013

An innovative way to non-intrusively measure weak electric fields in plasmas is presented. The electric field is produced between two planar plates which can be immersed in a thermionic plasma. An atomic probe beam, obtained from the conversion of H+ ions into H(2s) in a resonant charge exchange cesium vapor cell, is sent between the two plates. Emission of the Lyman- line is induced by the external electric field. It originates in the Stark mixing of the two 2s1/2 and 2p1/2 levels that are separated in energy by the so-called Lamb shift. The light is collected in a direction perpendicular to the probe beam. Theory predicts that its intensity is proportional to the square modulus of the electric field below a critical value. With a proper calibration through measurements in vacuum, the amplitude of the electric field is obtained. Creating an electric field within a plasma, Debye shielding is thus clearly observed. Such measurement can also be done in transparent diluted media. The presented method answers to a long-standing challenge in experimental physics. © Copyright EPLA, 2013.


Hauri E.H.,Carnegie Institution of Washington | Papineau D.,Carnegie Institution of Washington | Papineau D.,University College London | Wang J.,Carnegie Institution of Washington | Hillion F.,Cameca SAS
Chemical Geology | Year: 2016

We report here data of multiple sulfur isotopes (32S, 33S, and 34S) measured by NanoSIMS 50L ion microprobe in Fe-Ni-Cu standards, and pyrite grains recovered from the Neoarchean Abitibi Supracrustal Terrain, Canada. Careful attention to instrument tuning, sample preparation and sample stage positioning results in highly precise and accurate data for 32S-33S-34S similar to that of larger radius SIMS instruments. Our results using a multi-Faraday collection system demonstrate that the NanoSIMS 50L instrument is capable of high-precision measurements of multiple isotopes of sulfur capable of resolving mass-independent variations in 33S ({increment}33S) on the order of 0.4‰ (2σ) with improvements possible with higher S count rates. Pyrite grains from the Abitibi Supracrustal terrane have a large range of δ34S values between -9.6 and +6.3‰, and corresponding {increment}33S values between -0.8 and +1.5‰, consistent with other datasets from Neoarchean sedimentary rocks. The new data indicate the incorporation of atmospheric sulfur affected by mass-independent fractionation (MIF) of 33S into the Neoarchean marine sulfur cycle and point to subsequent sulfate reducing microorganisms at that time. © 2015 Elsevier B.V..


Merkulov A.,Cameca SAS
Surface and Interface Analysis | Year: 2013

Secondary negative ions yields of elements in the IIIrd, IV th, Vth periodic table groups emitted under Cs+ bombardment of Si surface in presence of oxygen are reported. The ion yield variation on oxygen partial pressure in the analytical chamber obtained for different ions allows taking a step forward the development of secondary ion emission model. The ion yield enhancement under particular oxygen surface coverage offers an approach for quantitative analysis of ultra-shallow semiconductor structures and interfaces. Copyright © 2012 John Wiley & Sons, Ltd. Copyright © 2012 John Wiley & Sons, Ltd.


Lejeune A.,Center University Of Saint Jerome | Lejeune A.,Cameca SAS | Cherigier-Kovacic L.,Center University Of Saint Jerome | Doveil F.,Center University Of Saint Jerome
AIP Conference Proceedings | Year: 2014

Answering to a long-standing challenge, a new way to non-intrusively measure weak electric fields in plasmas is presented. Here we show it using an H(2s) atomic probe beam, obtained from the conversion of H+ ions into H(2s) either by collisions with H2 residual gas or in a resonant charge exchange cesium cell. The probe beam is sent between two polarized plates creating an electric field applied within a thermionic plasma. Indeed the interaction between a metastable H(2s) atomic hydrogen beam and an external electric field leads to the emission of the Lyman-alpha line owing to the Stark mixing of the 2s1/2 and 2p1/2 levels. When the field is weak, it can be treated as a perturbation of these two states separated by a small amount of energy called Lamb-shift. It induces a radiation with intensity proportional to the square modulus of the electric field which is measured in a direction perpendicular to the probe beam. Contrary to measurements in vacuum, the Debye sheath formation is clearly observed in the presence of plasma. This contribution reviews: presentation of Stark mixing of the 2s1/2 and 2p1/2 levels and of Lamb shift for hydrogen-like atoms, brief description of the experimental set-up, observation of the formation of a sheath between two polarized plane electrodes in a plasma, either with a probe ion beam, or atom beam. © 2014 AIP Publishing LLC.


Kouzminov D.,Varian Semiconductor Equipment Associates | Merkulov A.,Cameca SAS | Arevalo E.,Varian Semiconductor Equipment Associates | Grossmann H.-J.,Varian Semiconductor Equipment Associates
Surface and Interface Analysis | Year: 2013

Secondary ion mass spectrometry analysis of ultra-shallow (sub-200 eV) B implants is complicated by the presence of native oxide on the surface of Si. Knowledge of the type of oxide present on the surface as well as accurate oxide thickness is very important for correct data reduction in extra-low energy depth profiling. Sputter rate (SR) variation approach based on the accurate SR measurement in Si and SiO2 can be successfully applied to B implants done through thermal oxides of various thicknesses. Lowest profiling energy should be used to achieve the least profile distortion in the case of de-channeled B implants: the rule of half of the implant energy used for profiling energy is confirmed. Profiling energy that is equal to the implant energy can be used if implantation is done through native oxide or into the stripped Si. If no thermal oxide is present on the surface, the most consistent result will be obtained when implants are done into the pre-stripped Si thus eliminating uncontrollable and variable native oxide-related issues. Copyright © 2012 John Wiley & Sons, Ltd. Copyright © 2012 John Wiley & Sons, Ltd.

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