HR: 11:35h
AN: SH32A-06 INVITED     [Abstracts]
TI: Solar Wind He and Ne - Implications of Surface Studies and Preliminary Data from Bulk Metallic Glass Flown on GENESIS
AU: * Grimberg, A
EM: grimberg@erdw.ethz.ch
AF: ETH Zuerich, Institute for Isotope Geology and Mineral Resources, Zuerich, 8092 Switzerland
AU: Heber, V S
EM: veronika.heber@erdw.ethz.ch
AF: ETH Zuerich, Institute for Isotope Geology and Mineral Resources, Zuerich, 8092 Switzerland
AU: Homan, O J
EM: otte.homan@first.ethz.ch
AF: ETH Zurich, Center for Micro- and Nanosciences 'FIRST', Zuerich, 8093 Switzerland
AU: Hays, C C
EM: cchays@mail2.jpl.nasa.gov
AF: CalTech, JPL, Pasadena, CA 91109 United States
AU: Jurewicz, A J
EM: Amy.J.Jurewicz@jpl.nasa.gov
AF: CalTech, JPL, Pasadena, CA 91109 United States
AU: Burnett, D S
SH32A-06 AF: CalTech, GPS, Pasadena, CA 91125 United States
AU: Baur, H
EM: baur@erdw.ethz.ch
AF: ETH Zuerich, Institute for Isotope Geology and Mineral Resources, Zuerich, 8092 Switzerland
AU: Wieler, R
EM: wieler@erdw.ethz.ch
AF: ETH Zuerich, Institute for Isotope Geology and Mineral Resources, Zuerich, 8092 Switzerland
AB: The Bulk Metallic Glass (BMG) flown on GENESIS is one of only a few target materials that survived the impact landing without major damage. Some scratches have led to localized noble gas loss but most particles do not harm He and Ne analyses due to their low gas content. To date, He and Ne isotopes from bulk solar wind in the BMG have been measured but precision will be improved. Preliminary data from pyrolysis extraction confirm previous values measured in SWC foils exposed on the lunar surface. However, the ⁴He/³He ratio of 2430 ±120 and the ²⁰Ne/²²Ne of 13.75 ±0.1 are slightly heavier than the SWC average. First measurements done with UV-laser ablation show higher ³He contents and an even heavier ²⁰Ne/²²Ne ratio of 14.04 ±0.1. Ne ratios are corrected for backscatter losses with a factor of 1.015 as calculated by TRIM whereas He correction factors are still not verified yet. The search for the He and Ne composition of Solar Energetic Particles (SEP) with stepwise etching has not been yet successful due to a molecular contamination (brown stain). This film was deposited on the BMG surface in space and is resistant to HNO₃, the most suitable acid for homogeneous BMG etching. Extensive X-ray photoelectron spectroscopy (XPS) analyses have been carried out on 90 spots covering the entire surface to determine composition and distribution of this brown stain. These data show that the brown stain is an ubiquitous organic layer mainly consisting of Si, C, O and minor F. Since the BMG element Zr is always visible in the XPS spectra, contamination at the measured spots is very unlikely to be thicker than 10 nm. Ultrasonic cleaning of the surface with common solvents removed about 50 % of the particles but did not affect the brown stain. Moreover it led to an apparent gas loss of ~30 % for He. Cleaning with oxygen plasma lowered the carbon-signal in the XPS spectra, however it did not remove the brown stain either. A combination of oxygen plasma ashing followed by plasma etching with SF₆ has potential to fully remove the Si-based contamination.
DE: 1009 Geochemical modeling (3610, 8410)
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 2114 Energetic particles (7514)
DE: 7514 Energetic particles (2114)
DE: 7599 General or miscellaneous
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005