IPG Photonics

About: IPG Photonics is a based out in . It is known for research contribution in the topics: Laser & Fiber laser. The organization has 903 authors who have published 1241 publications receiving 63339 citations.

μ-Erda developments in order to improve the water content determination in hydrous and nominally anhydrous mantle phases

Abstract: The precise knowledge of the water content in geological samples such as mantle minerals, volcanic glasses and glassy inclusions proves to be crucial information for the Earth Sciences because water has a considerable influence on physical and chemical properties of Earth’s mantle and crust. Among the nuclear microbeam techniques, elastic recoil detection analysis (ERDA) has been used at the nuclear microprobe of the Pierre Sue Laboratory (LPS) with a very good reliability for a long time to determine the water content of various materials. Previous ERDA measurements gave the total H content at a micrometric scale in the bulk of hydrous geologic samples. However, it was more difficult to characterize nominally anhydrous phases. Recent efforts allowed us to significantly improve the different steps of the ERDA analysis, from the sample preparation to the determination of the uncertainties of the resulting H concentration. A large series of very different geological samples has been measured: volcanic glasses and glassy inclusions, synthetic and natural nominally anhydrous minerals. Our new sample preparation protocol limited the thickness of the surface layer of H-pollution, leading to an easier differentiation of the bulk contribution. Simultaneous PIXE and RBS measurements allow the precise location of the interesting areas and also give information on the chemical characterization of the investigated samples, with respect to the major and minor elements. The processing of the list-mode acquisition files is made using the RISMIN software, allowing among other interesting features to check the absence of water loss under the beam. We will present the results of the H-content measurements and show the good agreement between our present results and those obtained by Fourier transform infrared spectroscopy (FTIR) for the same set of samples. The detection limit was measured on a dehydrated natural San Carlos olivine ((Mg,Fe)2SiO4) equal to 130 wt ppm H2O (15 wt ppm H or 300 at ppm H) and the relative uncertainties on the water concentration range from 10% to 15%.

Modern subsurface bacteria in pristine 2.7 Ga-old fossil stromatolite drillcore samples from the Fortescue Group, Western Australia.

Abstract: Background Several abiotic processes leading to the formation of life-like signatures or later contamination with actual biogenic traces can blur the interpretation of the earliest fossil record. In recent years, a large body of evidence showing the occurrence of diverse and active microbial communities in the terrestrial subsurface has accumulated. Considering the time elapsed since Archaean sedimentation, the contribution of subsurface microbial communities postdating the rock formation to the fossil biomarker pool and other biogenic remains in Archaean rocks may be far from negligible.