Progress in multiple sulfur isotope analysis by ion microprobe

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Welcome
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Viewing the world through ions An innovative
response to NSF MRI-R2

• University of Colorado
• Consortium for Research in Earth Science, Energy
  and Materials

Sensitivity, Performance, Resolution, Discovery,
Innovation
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Meeting Agenda

• Welcome and introductions (Steve Mojzsis)
• Background to the CRESCENT initiative
• Enhance discovery opportunities
• Increase analytical capabilities
• Partnership between units
• The Instrumentation we wish to pursue
• Alphachron U-Th/He (Becky Flowers)
• SIMS (ion microprobe) (Michel Schumacher)
• Summary and discussion

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We are at a critical moment in the Research
Infrastructural development of our country. A
reflection of that need is the ARRA and the new
MRI-R2 announced by the National Science
Foundation this May 11, 2009. We believe the time
is now to take leadership with a new initiative
in Geosciences, Energy Materials at the
University of Colorado.
Earth Science
Energy Resources
Materials Science/ Solid State Physics
Sensitivity, Performance, Resolution, Discovery,
Innovation
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High-spatial resolution, High-sensitivity
1µm
1000µm
Courtesy ACS
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Hardware requirements

• Hardware Costs
• Fully apportioned MC-SIMS 4.54 M (delivered)
• ASI Alphachron 0.354 M (delivered)
• NSF MRI request will be 3.350 M (with matching
  funds)
• Infrastructure needs
• Room size Minimum 7.1 x 5.1m (23 x 16 ft)
• Ceiling height 2.35 m (8 ft)
• Access door width Access door height 2.5 m (8
  ft) 2 m
• Laboratory floor load capacity
  3800 kg/m2 (6690 lb./yd2)
• Access path load capacity during move Elevator
  (3800 kg weight of rigging equipment) biggest
  part 2.5 (length) x 1.5 m (width) x 2 m
  (height), minimum capacity 4 000 kg
• Other specifications (power, vibration, etc.)
• Room BESC 145 in the Geology Building meets these
  specifications
• technical support
• One Full-time technician/Ion microprobe
  specialist for Y1-3
• Service contract 0.100 M/y for Y1-3

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Applications
Stable isotopes H/D Oxygen, Boron Nitrogen,
Carbon Sulfur, Silicon many many others
Geochronology zircon dating (U/Pb)
monazite apatite sphene many others possible
Earth Science
Energy Resources
Trace element analysis Rare earth elements
Mapping (lt0.5 µm)
Materials Science/ Solid State Physics
Depth profiling
Diffusion Studies
Geochemistry, Biochemistry/Medicine,
Environmental Chemistry, Materials Science/Solid
State physics, Nuclear Chemistry
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A LARGE RADIUS MAGNETIC SECTOR SIMS
Electrostatic field
Sector magnet
Ion sources
Detector system
Sample
Operator
A remarkably versatile instrument for a wide
range of applications
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Ion imaging as an ion microscope
Ion images show secondary ion intensities as a
function of location on sample surfaces. Image
dimensions vary from 500 µm to less than 10 µm
with lateral resolution of 0.5 µm. Requires a
combination ion microscope/mass spectrometer
capable of transmitting a mass selected ion beam
from the sample to the detector without loss of
lateral position information.
Au in FeS2
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Isotope ratios
Precision and accuracy requirements are high
. Since all of the isotopes of an element have
the same chemical properties, ionization and
detection efficiencies remain nearly constant for
the different isotopes .
Precisions of lt0.1 are commonplace and
accuracies approach precisions. Mass spectral
peaks should have flat tops and steep sides so
that slight magnet instability does not change
the ion signal intensity. SIMS has allowed us to
enhance data from electron beam studies with in
situ analysis at extremely high spatial
resolution, mass resolution, precision and
accuracy in the isotopes.
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Radiogenic and Stable isotopes with SIMS
Every rock on Earth contains a clock, a
thermometer and a barometer. Inside all rocks
and minerals are elements and isotopes that serve
as natural tracers. By examining the presence,
proportion and distribution of natural tracers,
we can reveal the conditions under which those
materials formed. Ion microprobes offer great
advantages over previous methods to glean natural
tracer information out of rocks. SIMS has
allowed us to investigate in situ the isotopic
character of materials at extremely high spatial
resolution.
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Depth profiling
Monitoring the secondary ion count rate of
selected elements as a function of time leads to
depth profiles. The above figure shows the raw
data for a measurement of phosphorous in a
silicon matrix.
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Analytical requirements
Diffusion studies

•   Flat crater bottom for high depth resolution.
• Efficient gating system to remove crater edge
  effects for high dynamic range.
• Efficient charge compensation
• Software for depth profile acquisition and data
  processing

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Diffusion studies
18O in alumina and albite
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Diffusion studies
Oxygen diffusion in grain boundaries

•   18O mapping

• Cs primary ions
• Negative secondary ions
• Microscope image mode
• Fast image acquisition over large area

18O mapping in NiO polycrystal, Field of view
150 µm Acq. Time 20 sec
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Trace element mapping

• 232Th and 238U mapping in a zircon crystal

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Gunflintia sp.
ion microscopy
Three-dimensional analyses are possible by
acquiring images as a function of sputtering time
(image depth profiles). Microscope sputtering
rates exceed microbeam rates, often by several
orders of magnitude. Thus microscope imaging
produces depth scales more compatible with the
scale of the lateral images.
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Biology/Medicine
Mammary carcinoma cells halogenous tracers
Reference Galle, P. INSERM, Creteil, France
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Biology/Medicine
Multiple isotope imaging on cultured cells
Reference Lechene, C. et al. Harvard Med.
School TSRI
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Biology plant physiology
Reference N. Grignon, Laboratoire Biochimie et
Physiologie Moleculaire des Plantes, Montpelier,
France
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Environmental O B in Carbonates
Oxygen variability in corals porites

• Reproducibility
• Oxygen 0.4
• Boron 0.9

C. Rollion-Bard, CRPG-Nancy
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Overview of SIMS capabilities
The IMS 1280 offers outstanding performance for
the full range of SIMS applications in Earth
Science, Biology, Medicine, Chemistry, Materials
Science/Solid State Physics trace element
(concentration, mapping) isotope ratios (stable
isotope, geochronology) Depth profile
External reproducibility better than 0.2 can be
routinely obtained for FC/FC, FC/EM and EM/EM in
mono- and multi-collection mode
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Summary

• Now we need your help
• We are committed to act on the new NSF call for
  MRIs.
• We will work in close partnership with the
  Geosciences Initiative, Energy Initiative and
  Micro/Nano Initiatives.
• We will build contacts with our colleagues at
  NREL, NIST and sister research institutions in
  the Rocky Mt. region.
• We envision an Open Facility to outside users.
• Our goal is to have a self-sustaining support
  plan for this facility, but we need to have
  significant support from the University to create
  a competitive proposal.