Download NanoSims and the Centre for Microscopy and Microanalysis

nanoSIMS:
a new analytical tool for
ultra-fine feature analysis
using secondary ion
emission
R. Stern* and Peta Clode
The University of Western Australia
Centre for Microscopy and Microanalysis
[email protected]
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nanoSIMS labs
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SIMS
Secondary Ion Mass Spectrometry
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probing analytical technique for measuring the surface or
near surface chemical or isotopic composition of solids
uses probe ions to sputter target ions in laterally
microscale or smaller regions (ion microprobe)
analytical characteristics:
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nm depth resolution
lateral resolution 10’s nm to mm
most sensitive of the probing analytical techniques, ppb-ppm
entire periodic table, H to U
simple sample preparation
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SIMS Data
cps,ppm Se
Basic
from tiny mass consumed
18 O/ 16O
24Mg/28Si
Mass spectrum
ratios
Dimensions:
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1 dimension
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2 dimensions
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‘image’ (map) of the surface
distribution of secondary ion species
3 dimensions
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‘depth profile’: composition along a line
Depth profile
normal to the surface
‘line scan’: composition along a line
Line scan
parallel to the surface
Image
a stacked series of secondary ion
images collected at discrete depths into
the target
The Centre for Microscopy & Microanalysis
SIMS analytical
Energy
Analyzer
Mass
Analyzer
Ion
source
Secondary ion
Collection
Optics
Primary ion
column
Detector
Sample
under
vacuum
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High mass resolution
analyzer
Detector array: 5
isotopes acquired
simultaneously
Ion sources: O-, Cs+
Normal, co-axial
primary & secondary
ions
samples
Sample introduction
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Features of NanoSIMS
dynamic SIMS
 for bulk sample ion chemical/isotopic characterization
 not for molecular identification or oxidation state
probe lateral resolution
 50 nm for 133Cs+
 200 nm for 16O-
ability to scan the primary beam and
record secondary ion images at ultrafine-scale lateral resolution
 very low eroson rate, ~nm/hr (sample preservation)
simultaneous multicollection of up to 5
isotope species
routine high mass resolution
 resolve isobaric interferences
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Ion imaging of TiCN alloy demonstrating sub-50 nm
edge resolution with Cs+
10 x 10 um, 24C2
3 x 3 um, 26CN
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Engineered Materials Minerals
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Semiconductors
Ceramics
Alloys
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Extraterrestrial dust
Geochronology
Ore minerals
BIOMATERIALS
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sub-cellular imaging
biochemical function
cancer research
pharmaceuticals
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NanoSIMS labs
0. Harvard Medical School/ MIT, Boston USA
National Resource for Mass Spectrometry Imaging, NIH NCRR
bio-SIMS program
1. Washington University, Saint Louis, MO
2. Max Planck Institute, Mainz, Germany
bio-SIMS program
3. Institut Curie, Paris, France
4. Oxford University, U.K
5. Lawrence Livermore National Lab, Livermore, CA, USA
University of California, Davis
6. National Institute for Materials Science, Tsukuba, Japan
bio-SIMS program
7. LAM, Centre de Recherche Public-GL, Luxembourg
8. ExxonMobil, New Jersey, USA
9. University of Tokyo
10. The UWA
bio-SIMS program
11. Rouen Univ, France
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Non-metallic elements used in SIMS biological analysis
Naturally-occurring isotopes
Artificial isotopes (stable or radioactive)
12C
14C
14N
– all cell organelles
– DNA, RNA, proteins
31P
– DNA, RNA (nucleic
acids)
32S
– proteins
– turnover/pathways of C
15N
– turnover/pathways of labelled
amino acids (proteins), nucleic acids
17F
– Fluoracil, cancer drug targetting
chromosomes
81Br
– in Bromodeoxyuridine (BrdU),
specifically incorporated into DNA
during DNA synthesis
123, 125, 127I
– in Iododeoxyuridine
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Examples of metallic elements used in SIMS biological
analysis
Li, Na, K, Rb, Cs
Be, Mg, Ca, Sr, Ba
Ti, Cr, Mn, Fe, Ni, Pb, Al, In
Au, Ag
Sc, lanthanides, actinides
to date, few studies, poor
sensitivity and spatial
resolution
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O- primary ion bombardment, positive
secondary ions, and a silicon matrix
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Cs+ primary ion bombardment, negative
secondary ions, and a silicon matrix
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Sample preparation
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must be dehydrated, +/- fast freezing, chemical fixation
(glutaraldehyde, Os tetroxide), epoxy embedding, cryo-sectioning
(0.3 – 1 µm)
will feature of interest be preserved?
other documentation techniques to map features (confocal,
VPSEM, TEM, etc.)
Example of human hair cross-section deposited on Si (Hallegot and Corcuff, 1993)
Scanning electron microscopy images
cortex
cuticle
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nanoSIMS samples
Sample holder for 1 cm samples
Thin membranes on
Si wafer
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Imaging of resin embedded biological tissues
12C14N
32S
A mucous-producing
150
mm
cell in coral tissue
Scale = 3um
Primary ions: Cs+
12C14N
31P
A symbiotic algae in
coral tissue
Scale = 2um
Primary ions: Cs+
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Imaging isotopic tracers in resin embedded biological
tissues
44Ca
/
40Ca
44Ca
used as a tracer of calcium
(40Ca) to determine pathways of
movement & uptake
1.
4.
3.
Coral epithelium
44Ca 1 min
Scale = 5um
FOV = 35um
Primary ions: O-
150 mm
2.
Significant
44Ca
uptake
Region
44Ca/40Ca
Natural abundance
0.02
1. Mucous cell
0.05
2. Spiked Seawater
0.7
3. Epithelial cells
0.37
4. Stinging cell
0.02
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Mouse cochlea cells
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Imaging of As within human hair
Audinot et al. (2003)
Heavy metal exposure
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Analytical Issues:
will the metal ions be detectable?
are there non-metallic ion labels that
can be used as proxies for the metals?
quantitation: how important?
sample preparation to avoid element
migration or loss
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nanoSIMS & ARC Metals in
Medicine
is capable of playing a vital role
the analytical capabilities and
experience with metals in biological
media needs to be developed
R. Stern and P. Clode are here to enter
into research partnerships with you
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