New Science from new Technology: NanoSIMS and RIMS

1. New Science from new Technology: NanoSIMS and RIMS Peter Hoppe Max-Planck-Institute for Chemistry IAU Meeting 2006 Prague August 21, 2006

2. Outline 1. Introduction • NanoSIMS 50 Ion Microprobe 3. RIMS - Charisma 4. NanoSIMS Studies 4.1. Submicrometer-sized Presolar Grains 4.2. Isotopic Homogeneity within Presolar Grains 4.3. Presolar Silicates 4.4. Coordinated NanoSIMS-TEM Studies • RIMS Studies 5.1. SiC Mainstream Grains 5.2. SiC X Grains 6. Summary

3. Introduction (I) Presolar Minerals

4. Introduction (II) Presolar SiC Populations

5. Introduction (III) Isotope Analyses of Presolar Grains • Noble gas mass spectrometry of bulk samples (late 1980s, early 1990s) • Conventional SIMS (late 1980s, 1990s, early 2000s) • RIMS (late 1990s) • NanoSIMS (2000s)

6. Introduction (IV) The Role of NanoSIMS and RIMS • NanoSIMS: • Analysis of submicrometer-sized presolar dust • In-situ search for presolar dust • Investigation of isotopic heterogeneity within grains • RIMS: • Isotopic compositions of heavy elements in individual grains

7. NanoSIMS 50 (I) • Commercial ion microprobe from Cameca • Introduction to field of cosmochemistry in 2001 (Washington University, St. Louis and MPI for Chemistry, Mainz) • Three fundamental features: 1. Small beam size (down to 50 nm for Cs+-ions) 2. High transmission at high mass resolution (30x higher than in the IMS3f for conditions used for O-isotopic measurements) 3. Simultaneous detection of up to five isotopes (minimum mass separation is M/30, i.e., isotopes up to mass 30 (Si) can be measured simultaneously

8. NanoSIMS 50 (II)

9. RIMS - Charisma • Most advanced (in the field): CHARISMA(Chicago-Argonne Resonant IonizationSpectrometer for Mass Analysis) • Laser ablation + laser ionization + TOF-MS • Superior to SIMS for trace elements , especially such with small ion yields in SIMS • Basically a single-element-method • First applications: Fe, Sr, Zr, Mo, Ru, and Ba in single presolar SiC & graphite grains • Prospects: • “Useful yield” of current setup ~ 1 % • Planned modification: aiming at ~ 30%

10. CHARISMA – Schematics (I)

11. CHARISMA – Schematics (II)

12. NanoSIMS Studies (I) Submicrometer-sized Presolar Grains • Most presolar grains are submicrometer in size • Previous characterization was biased • NanoSIMS made it possible to obtain information on previously largely unexplored presolar grain types: • Sub-population of presolar SiC with specific Si-isotopic signature • Presolar spinel (MgAl2O4)

13. NanoSIMS Studies (II) O in Presolar Spinel Zinner et al., 2005

14. NanoSIMS Studies (III) Isotopic Homogeneity within Presolar Grains • Isotopic homogeneity can be studied within micrometer-sized presolar grains • In most cases isotopic compositions turned out to be homogeneous • Isotopic heterogeneities: • TiC within graphite • SiC from supernovae

15. 16O 17O/16O 18O/16O Standard grain 17O/16O 16O 18O/16O 1 mm 48Ti 28Si Sah-602-4 min max NanoSIMS Studies (IV) O in Presolar Corundum Mostefaoui et al., 2002

16. NanoSIMS Studies (V) Presolar SiC-X Besmehn and Hoppe, 2003

17. 30Si/28Si 28Si 1 mm 28Si 29Si/28Si 30Si/28Si min max NanoSIMS Studies (VI) Presolar SiC-X Besmehn and Hoppe, 2003

18. NanoSIMS Studies (VII) Presolar Silicates • Most presolar minerals can be separated by harsh chemical treatments from meteorites • Does not hold for silicates • Silicates are the major constituent of O-rich dust around stars • First silicates discovered in an IDP in 2002 (Messenger et al.); use of NanoSIMS was essential • O-isotopic mapping of slices of meteorites or IDPs with 100 nm lateral resolution

19. NanoSIMS Studies (VIII) Presolar Silicates 16O 17O 17O/16O Acfer 094 Meteorite (Mostefaoui and Hoppe, 2004)

20. NanoSIMS Studies (IX) Coordinated NanoSIMS-TEM Studies • Simultaneous information on mineralogy, structure, isotopic compositions, and petrological context of presolar materials • Preparation of thin sections of individual particles by ultra-microtomy or FIB lift-out

21. NanoSIMS Studies (X) Presolar SiC-X 1 3 2 NRL, Carnegie Institution, and MPI Mainz, 2004, unpublished

22. s-process path RIMS Studies (I) Zr in SiC mainstream grains Nicolussi et al., 1997

23. RIMS Studies (II) Zr in SiC mainstream grains Lessons from Zr: • Mainstream SiC grains come from low-mass AGB stars, probably mostly 1.5–3 M; 5 M can be excluded • A variety of conditions are required to explain the array of grain compositions • Models do a good job of explaining most of the data, but low 96Zr grains remain a difficulty

24. RIMS Studies (III) 99Tc in SiC mainstream grains Savina et al., 2004

25. RIMS Studies (IV) • Although previously postulated, a new type of nucleosynthesis was recognized in nature • The neutron burst required is a natural consequence of Type II supernova explosions • X-grains must come from Type II, not Type Ia supernovae, as such a burst does not occur in SN Ia Mo in SiC X grains Pellin et al., 1999

26. Summary • NanoSIMS and RIMS have become well-established tools in presolar grain research • Important breakthroughs: • Extension of isotope analyses to submicrometer-sized grains • Study of isotopic homogeneity within micrometer-sized grains • Discovery of presolar silicate grains • Isotope analyses of the heavy elements by RIMS provided important input for a better understanding of neutron-capture reactions in the grain’s parent stars