The Centre for Microscopy & Microanalysis NanoSIMS 50 nanoSIMS: a new analytical tool for ultra-fine...

The Centre for Microscopy & MicroanalysisNanoSIMS 50NanoSIMS 50

nanoSIMS: a new analytical tool for ultra-fine feature analysis using secondary ion emission

R. Stern* and Peta ClodeThe University of Western AustraliaCentre for Microscopy and [email protected]


nanoSIMS labs

#10


SIMS

Secondary Ion Mass Spectrometry 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: nm depth resolution lateral resolution 10’s nm to m most sensitive of the probing analytical techniques, ppb-ppm entire periodic table, H to U simple sample preparation


SIMS Data

Dimensions: 1 dimension

‘depth profile’: composition along a line normal to the surface

‘line scan’: composition along a line parallel to the surface

2 dimensions ‘image’ (map) of the surface

distribution of secondary ion species 3 dimensions

a stacked series of secondary ion images collected at discrete depths into the target

Image

Depth profile

Line scan

ratios

18 16O/ O24Mg/28Si

Mass spectrum

cps,ppm Se

Basicfrom tiny mass consumed


Sample under

vacuum

Ionsource

Primary ioncolumn

Secondary ionCollection

Optics

EnergyAnalyzer

Detector

MassAnalyzer

SIMS analytical


Ion sources: O-, Cs+

Normal, co-axial primary & secondary

ions

Detector array: 5 isotopes acquired

simultaneously

High mass resolution analyzer

samples

Sample introduction


Features of NanoSIMSdynamic 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 ultra-fine-scale lateral resolution very low eroson rate, ~nm/hr (sample preservation)

simultaneous multicollection of up to 5 isotope speciesroutine high mass resolution

resolve isobaric interferences


Ion imaging of TiCN alloy demonstrating sub-50 nm edge resolution with Cs+

10 x 10 um, 24C2

3 x 3 um, 26CN


MineralsMinerals Extraterrestrial Extraterrestrial

dustdust GeochronologyGeochronology Ore mineralsOre minerals

Engineered Engineered MaterialsMaterials

SemiconductorsSemiconductors CeramicsCeramics AlloysAlloys

BIOMATERIALSBIOMATERIALS

sub-cellular imagingsub-cellular imaging biochemical functionbiochemical function cancer researchcancer research pharmaceuticalspharmaceuticals


0. Harvard Medical School/ MIT, Boston USA National Resource for Mass Spectrometry Imaging, NIH NCRR

1. Washington University, Saint Louis, MO

2. Max Planck Institute, Mainz, Germany

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

7. LAM, Centre de Recherche Public-GL, Luxembourg

8. ExxonMobil, New Jersey, USA

9. University of Tokyo

10. The UWA

11. Rouen Univ, France

NanoSIMS labsNanoSIMS labs

bio-SIMS program

bio-SIMS program

bio-SIMS program

bio-SIMS program


Naturally-occurring isotopes

12C – all cell organelles

14N – DNA, RNA, proteins

31P – DNA, RNA (nucleic acids)

32S – proteins

Artificial isotopes (stable or radioactive)

14C – 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

Non-metallic elements used in SIMS biological analysisNon-metallic elements used in SIMS biological analysis


Examples of metallic elements used in SIMS biological Examples of metallic elements used in SIMS biological analysisanalysis

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


O- primary ion bombardment, positive secondary ions, and a silicon matrix


Cs+ primary ion bombardment, negative secondary ions, and a silicon matrix


cortex

cuticle

Scanning electron microscopy images

Example of human hair cross-section deposited on Si (Hallegot and Corcuff, 1993)

Sample preparation 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.)


nanoSIMS samples

Thin membranes on Si wafer

Sample holder for 1 cm samples


Imaging of resin embedded biological tissuesImaging of resin embedded biological tissues

150 mA mucous-producing cell in coral tissue

Scale = 3um

Primary ions: Cs+

12C14N 32S

12C14N 31P

A symbiotic algae in coral tissue

Scale = 2um

Primary ions: Cs+


Imaging isotopic tracers in resin embedded Imaging isotopic tracers in resin embedded biological tissuesbiological tissues

150 m

Coral epithelium44Ca 1 minScale = 5umFOV = 35umPrimary ions: O-

1.1.

2.2.3.3.4.4.

44Ca / 40Ca 44Ca used as a tracer of calcium (40Ca) to determine pathways of movement & uptake

Region44Ca/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

Significant

44Ca uptake


Mouse cochlea cellsMouse cochlea cells


Heavy metal exposure

Audinot et al. (2003)

Imaging of As within human Imaging of As within human hairhair


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


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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