17 February 2017 Reproducing space weathering of olivine by using high-energy femtosecond laser pulses
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Atmospheric-free bodies of the solar system are undergoing several processes that alter their original spectral characteristics. The whole of these processes is the so-called space weathering. The surface of such bodies is exposed to the solar wind irradiation and to the ongoing bombardment of micrometeoroids yielding material modifications at the micro- and nanometer scale. In order to understand these processes and clarify the influence on spectral reflectance and absorption, numerous experimental approaches using ion and laser irradiation have been presented so far. However, up to this date, basic damaging mechanisms are still unresolved or cannot be completely reproduced.

In this work, we present the application of ultra-short laser pulses as a tool to reproduce space weathering, with focus on micrometeoroid impacts. In our experiments, slices of single-crystal olivine were irradiated under vacuum condition using 100 fs single-shot laser pulses. In order to perform spectral measurements, the laser-damaged regions were distributed over the sample surface within a grid geometry. After laser processing, a comprehensive study was performed by using spectroscopic measurements in the NUV-vis-NIR range, white light interferometry, SEM and TEM analysis. The cross-sections of the laser-generated craters reveal different layers including from the top to the bottom: an amorphous layer, two polycrystalline layers with different textures, and a defect-rich olivine substrate. Moreover, iron nanoparticles occur within the lower part of the amorphous layer and the polycrystalline layer. We can reproduce microcraters whose morphology, microstructure, and distribution of iron nanoparticles are similar to those found in the soil samples of the Moon or of the asteroid 25143 Itokawa.
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Agnese Fazio, Agnese Fazio, Gabor Matthäus, Gabor Matthäus, Dennis Harries, Dennis Harries, Harald Mutschke, Harald Mutschke, Stefan Nolte, Stefan Nolte, Falko Langenhorst, Falko Langenhorst, } "Reproducing space weathering of olivine by using high-energy femtosecond laser pulses", Proc. SPIE 10094, Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XVII, 100941D (17 February 2017); doi: 10.1117/12.2252130; https://doi.org/10.1117/12.2252130


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