Depth profiling of genesis solar wind collectors with laser post-ionization SNMS

Abstract

The samples returned to Earth by the Genesis mission of NASA's Discovery Program contain a record of the elemental and isotopic abundances of the solar wind. This record is implanted in the near-surface region of the sample collectors allowing the solar wind material to be distinguished from terrestrial contamination, which occurred due to the abrupt landing of the Genesis spacecraft. At Argonne National Laboratory, we have recently developed a new laser post-ionization secondary neutral mass spectrometer (LPI–SNMS) called SARISA, which is capable of accurate measurements of ultra-trace concentrations of many metallic elements implanted in Genesis solar wind collectors. In this work, we will report results of our measurements of abundances of Mg in two types of such collectors, silicon and diamond-like carbon (film on silicon). These depth profiling measurements were conducted in resonance-enhanced multi-photon ionization (REMPI) regime, in two-color scheme with two Ti-sapphire postionization lasers tuned to 285.30 nm and 375.66 nm wavelengths, with the repetition rate of 1 kHz.

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