@article{MarkusMorozArnoldetal.2018, author = {Markus, Kathrin and Moroz, Lyuba and Arnold, Gabriele and Henckel, Daniela and Hiesinger, Harald and Rohrbach, Arno and Klemme, Stephan}, title = {Reflectance spectra of synthetic Fe-free ortho- and clinoenstatites in the UV/VIS/IR and implications for remote sensing detection of Fe-free pyroxenes on planetary surfaces}, series = {Planetary and space science}, volume = {159}, journal = {Planetary and space science}, publisher = {Elsevier}, address = {Oxford}, issn = {0032-0633}, doi = {10.1016/j.pss.2018.04.006}, pages = {43 -- 55}, year = {2018}, abstract = {Both enstatite spectra are very bright in the VIS and NIR and show almost neutral to slightly bluish spectral slopes with a steep absorption in the UV. Very low iron in the enstatites (below similar to 0.04 wt\% FeO) already results in weak albeit noticeable absorptions in the VNIR between 0.4 and 0.9 mu m. Orthoenstatite and clinoenstatite are not distinguishable based only on their spectra in the VIS and NIR. At the Reststrahlen bands in the MIR a systematic difference in the number and exact position of local minima at similar to 10 mu m between clinoenstatite and orthoenstatite is evident. This can be used to discern between the polymorphs in this wavelength range. Additionally, we can distinguish between Fe-free low- and high-Ca pyroxenes in the MIR.}, language = {en} } @article{KlemmeFeldhausPotapkinetal.2021, author = {Klemme, Stephan and Feldhaus, Michael and Potapkin, Vasily and Wilke, Max and Borchert, Manuela and Louvel, Marion and Loges, Anselm and Rohrbach, Arno and Weitkamp, Petra and Welter, Edmund and Kokh, Maria A. and Schmidt, Christian and Testemale, Denis}, title = {A hydrothermal apparatus for x-ray absorption spectroscopy of hydrothermal fluids at DESY}, series = {Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques}, volume = {92}, journal = {Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques}, number = {6}, publisher = {AIP Publishing}, address = {Melville}, issn = {0034-6748}, doi = {10.1063/5.0044767}, pages = {6}, year = {2021}, abstract = {We present a new autoclave that enables in situ characterization of hydrothermal fluids at high pressures and high temperatures at synchrotron x-ray radiation sources. The autoclave has been specifically designed to enable x-ray absorption spectroscopy in fluids with applications to mineral solubility and element speciation analysis in hydrothermal fluids in complex compositions. However, other applications, such as Raman spectroscopy, in high-pressure fluids are also possible with the autoclave. First experiments were run at pressures between 100 and 600 bars and at temperatures between 25 degrees C and 550 degrees C, and preliminary results on scheelite dissolution in fluids of different compositions show that the autoclave is well suited to study the behavior of ore-forming metals at P-T conditions relevant to the Earth's crust.}, language = {en} }