Kein Folientitel

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• High Resolution Surface Mass Spectrometry
• by
• TOF-SIMS
• The challenge of chemical nanoanalysis
• Secondary Ion Mass Spectrometry - SIMS
• Analytical application of TOF-SIMS
• Perspectives

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• Key questions in nanoanalysis
• Identification (What?)
• Localisation (Where?)
• Quantification (How much?)

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Nanotechnology De
finition In at least one dimension
lt100nm Example Surface
mapping Lateral
resolution 100 nm
Information depth 1 nm
?
Volume 1x100x100 nm3
Amount of material 0.1 attomole
some 10.000
molecules
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• Chemical information ?
• Proximity probes (AFM, SNOM, ..... )
• Electron emission based probes (XPS, AES, TEM,
  .)
• Surface mass spectrometry
• Excitation by
• Electrons
• Electrical fields ? Atom probe
• Photons ? MALDI
• Ions ? Secondary Ion Mass Spectrometry (SIMS)

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Ag catalyst
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Secondary Ion Emission
M ?
Xiq X1, X2, X3, ...... Xi,
............... X1-, X2-, X3-, ....... Xi-,
............... X1o, X2o, X3o, ....... Xio,
...............
Transformation probability  P (M ? Xiq)
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Static SIMS
? Negligible probability of bombarding a damaged
area

• Sputtering of only a negligible fraction of the
  uppermost monolayer
• Reduction of the primary ion current (fluence)
• Reduction of the secondary ion current
• Resulting conditions/requirements
• High transformation probabilities
• High transmission mass spectrometer
• High sensitivity secondary ion detection

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Monolayer Sputtering ?(t)
?(0) . exp (- s .? . t) ?(t) Fractional
coverage at time t s Damage cross section ?
Primary ion flux density ?(0) Fractional
coverage at t 0
Lifetime t of one Monolayer  ?(t)
?(0) . 1/e
t 1/( s.?)
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Ag catalyst
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Ag catalyst
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ML sputtering
Example octanethiol on Au ?
1,34. 10-14 cm2
Static SIMS
I 0.6 pA A 1.56?10-4 cm2 ? 134?10-16 cm2
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Mass analysers applied in Static SIMS
(Historical
development) Magnetic sector field
? Quadrupole ? (FT-ICR) ? Time
- of - Flight
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TOF-SIMS
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• Main features of TOF-SIMS
• Parallel mass detection
• High (unlimited) mass range
• High mass resolution gt 10 000
• High mass accuracy (1-10 ppm)
• High transmission for high masses and at high
  mass resolution
• All elements and isotopes
• Molecular species
• High sensitivity (ppb, attomole)
• High lateral (50 nm)and depth (1nm) resolution

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Static SIMS Oxidized and contaminated molybdenum
surface (1973)
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Molecular Information by Static SIMS
Example Polystyrene

• I Intact Molecules (m lt 10,000 u)
• (MH), (MAg), (MNa),(M-H)-, ...
• (substrate cationization only from
  (sub)monolayer coverages)
• II Characteristic Large Fragments
• loss of functional groups,repeat
  units,..(according to classical
  fragmentation rules)
• III Small Organic Fragments
• end groups, fractions of repeat units, side
  chains,.(sufficient for identification)

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Static SIMS Phenylalanylglycine ML on Ag (1981)
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Cyclosporine A
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Conservation of charge signe
- Examples - Al-oxide
? Al, O-, AlO, AlO2-, .....
Ag-sulfate ? Ag, SO4- , ........ M on
Ag ? MH, M-H-, MAg, ...... Me-Cs
? Me-, Cs, .......

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Transformation probabilities (M ?
Xiq)
-Examples - Al
P (Al ? Al)
0,007 Al-oxide P (Al ? Al)
0,7 Ag-sulfate P (-SO4 ?
SO4-) 0,3 Me - Cs P (Cs ?
Cs) 1,0 Ag - Methionine P
(M?MH) 0,005 Ag - Bradikinin P
(M?MH) 0,0001 (1.060
amu) Ag - Mellitin P (M?MH)
0,000 000 5 (2.846 amu)
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Damage cross sections s - Examples -
System
s/10-14cm2 d/nm Ni - O
0,25
0,5 Ni - H 0,5
0,7 Ni - H2
4,5 2,1 Au - Thiole
1,3 1,1 Ag -
Methionine 4,5 2,3
Ag - Bradikinin 20,0
4,9 (1.060 amu) Ag - Melittin
45,0 7,4
(2.846 amu)
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• Sample materials, geometries, operation modes
• ? Sample materials
• Metals, Semiconductors, Oxides,
• Glasses, Ceramics,
• Polymers, Additives, Biopolymers, Biomolecules
• Biological tissues
• ? Sample geometries
• Surfaces, Monolayers, Particles, Fibers, .....
• ? Operation modes
• Spectroscopy
• Imaging (mapping)
• Depth profiling
• 3D-analysis

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TOF - SIMS
activities ? 250 laboratories are operating
TOF-SIMS instruments worldwide ? Bienniel
International SIMS Conferences 2005 SIMS 15
(Manchester) 2007 SIMS 16 (Japan) (350
450 participants) ? Bienniel European SIMS
Conferences in Münster, Germany 2006  SIMS
Europe V (200 250 participants)
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(Static) SIMS Optimisation ? Mass
Spectrometry Magnetic sector field ? Quadrupole )
? (FT-ICR) ? Time-of-Flight ? Lateral
resolution Focused ion beams ? Depth
resolution Cluster bombardment Low energy PI
? P(M?X) Oxidation, Cs deposition Nobel
metal substrates Cluster bombardment
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Mass resolution, accuracy
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Lateral resolution
Example Photographic Crystals
lateral distribution of Cl- on cubic silver
halide crystals
line profile ?x16-84 50 nm
(Sample provided by the University of Antwerp,
Belgium (Prof. Gijbels))
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Deth resolution B monolayer in Si
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Yield
Influence of the Substrate and the Surface
Coverage
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Cluster bombardment O ? Ar ? Xe ? SF5 ? CmHn ?
C60 Ga ? Aun ? Bin
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• Main features of TOF-SIMS
• Parallel mass detection
• High (unlimited) mass range
• High mass resolution gt 10 000
• High mass accuracy (1-10 ppm)
• High transmission for high masses and at high
  mass resolution
• All elements and isotopes
• Molecular species
• High sensitivity (ppb, attomole)
• High lateral (50 nm)and depth (1nm) resolution

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Trace Metal Detection / mass resolution
mass resolution (FWHM) Ti 13119 Cr 12813 Fe
12009 Cu 13849
coverage (atoms/cm2) Ti 6.1E10 Cr 8.2E09 Fe
3.1E09 Cu 2.1E10
data taken from 003_r.dat
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TOF-SIMS Detection Limits
1 Monolayer 1.5E15 atoms/cm²)
? the error is estimated to be within a factor of
2 to 3.
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Depth profiling
Reconstructed profile (Li, Na)
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Material Science
2D Images and Cross Sections
(Sample provided by Prof. Martin, RWTH Aachen,
Germany)
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Surface Imaging
Blooming Effect on Polymer
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Particle Analysis / Uranium
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Nanoextraction

Laser-SNMS
overlay
TOF-SIMS
overlay
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LB-multilayer system Lipids DPPC/DPPG (41),
Protein 0.4 mol SP-C
Protein
Lipid
Phase Separation
Laser- SNMS
FLM
dye-labeled lipid
30 CH4N
58 C3H8N
10 µm
TOF- SIMS
AFM
topography
110 C5H8N3
58 C3H8N
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Au2 imaging - Placenta cell complex
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Mouse Brain Section
Correlation Analysis 3 Colour Overlay
Field of View 8 x 8 mm2
corpus callosum
Fe
caudateputammen
sum of phospholipid ions
canteriorcommissure
sum ofcholesterol ions
nucleustriangularissepti
Example provided by Alain Brunelle,ICSN, CNRS,
France
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Rat Brain CrossSection
Field of View 18 x 18 mm2
255 Carboxylate 283 C18 Fatty acid 771
Phospholipid 892 Triclyceride
to be published by A. Brunelle et. al. ICSN,
CNRS, France
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Salbutamol
Field of View 52.7 x 52.7 µm2
one pixel 100 x 100 nm2

• only 100 shots applied
• 20 integral counts

Salbutamol
Salbutamol (MH) max counts 20 total
counts 2.12 x 105
? 2 x 10-20 mole detected from a 100 nm spot
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Applications in Life
Sciences ? Fundamental research Tissues, cells,
membranes, biopolymers, lipids,
...... Biomedicine, biology, biochemistry. ?
Diagnostics Biochips, chromatographies,
nanofluidics, marker, molecular pathology,
.. ? Drugs Delivery systems (tablets,
nanoparticles, polymers,..), localisation in
cells and tissues (ADME), contamination,
screening, ...... ? Biomaterials Artificial
membranes, substrates for cell growth and
artificial tissues, protein- and cell-adhesion,
biocompatibility, .....
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Directions of future development
? Fundamental research Understanding the
secondary ion formation process Experimental and
theoretical model systems UHV experiments ?
Technical development Sensitivity
Impact cascade, chemical environment, Laser-SNMS,
.. Lateral resolution Spot size, impact
cascade Depth resolution Impact cascade ?
Instrument development New cluster ions (N,O,He,
metals, .... ) Cluster FIB Laser-SNMS ?
Analytical application Nanoelectronics and
nanomaterials Nanobioanalytics Nanoparticles
Transformation probabilities ?1 ?l below10nm
(control of beam diameter and impact
cascade) Moleculare 3D-analysis Selective bonding
and yield control
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Some challenges in molecular
nanoanalysis ? Single Molecule Detection /
Identification Subattomol-Analytics, sample fixed
in a well-defined surface area ? Individual Cell
Analysis Chemical content of a single cell (ML
separation) ? SIMS Chip Chip-arrays for selected
molecular species (or classes of
molecules) Microstructured and -functionalized
surfaces (separation, yield optimisation)
Selective bonding and yield control ? Zeptomole
Detector TLC, Gelchromatography ,
Isotachophoresis, ....... ? Nanoproteomics
Immobilysed enzymes (trypsine) ? Moleculare
Pathology Electron microscopy ? Imaging
TOF-SIMS