Physics
Scientific paper
Dec 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011agufm.p43a1653d&link_type=abstract
American Geophysical Union, Fall Meeting 2011, abstract #P43A-1653
Physics
[1155] Geochronology / Extinct Radionuclide Geochronology, [2129] Interplanetary Physics / Interplanetary Dust, [6015] Planetary Sciences: Comets And Small Bodies / Dust, [6094] Planetary Sciences: Comets And Small Bodies / Instruments And Techniques
Scientific paper
The small sizes of samples returned by recent (Stardust, Hayabusa) and future (OSIRIS-REx) sample return missions to comets and asteroids, as well as the small sizes of presolar grains in and interplanetary dust particles (IDPs) are driving improvements in lateral resolution and sensitivity beyond what is available with current state-of-the-art secondary ion mass spectrometry (SIMS) instruments. SIMS lateral resolution has reached ~50 nm and useful yields are at most a few percent. We are completing construction of CHILI (the CHicago Instrument for Laser Ionization), a resonant ionization mass spectrometry (RIMS) nanobeam instrument designed for isotopic and chemical analysis at the few-nm scale with a useful yield of ≥35% [1]. CHILI is equipped with a COBRA-FIB high resolution liquid metal ion gun (LMIG) and an e-CLIPSE Plus field emission electron gun from Orsay Physics, each of which can be focused to <4 nm. The electron gun will be used for secondary electron imaging, as the built-in optical microscope is diffraction-limited to ~0.5 μm. A piezoelectric stage capable of reproducible nm-scale motions and equipped with a sample holder that will accept a wide variety of sample mounts is operational. The flight tube for the time-of-flight mass spectrometer mounted vertically above the sample chamber; this assembly is mounted in the center of an H-shaped laser table equipped with active vibration cancellation devices. The table has been demonstrated to have a vertical vibrational amplitude of less than 0.2 nm. Resonant ionization will be done with six Ti:sapphire tunable solid state lasers pumped with three 40W Nd:YLF lasers, which will allow two to three elements to be analyzed simultaneously. Ion detection in existing RIMS instruments [2,3] is done with a microchannel plate with a single anode. Isotope ratio precision is limited by counting statistics, as no more than one ion of the most abundant isotope of an element can be counted for each pulse. CHILI will initially be equipped with such a detector, but we are developing a multianode detector to significantly improve the count-rate capability. CHILI reflects many recent developments in instrument design, and most technical properties are pushed towards their physical limits. CHILI will be applied to a multitude of cosmochemical problems such as analysis of cometary and contemporary interstellar dust from the Stardust mission, asteroidal dust from the Hayabusa mission, a wide variety of samples from meteorites and IDPs, and, in a few years, asteroidal samples returned by the OSIRIS-REx mission. [1] Stephan et al. (2011) LPS 42, #1995. [2] Savina et al. (2003) GCA 67, 3215. [3] Veryovkin et al. (2008) LPS 39, #2396.
Davis Aileen M.
King Andrew
Liu Na
Pellin Michael
Savina M.
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