Zagreb ion microprobe, applications in materials

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Zagreb ion microprobe, applications in materials
modification and archeometry Iva Bogdanovic
Radovic Laboratory for ion beam
interactions Ruder Bokovic Institute Zagreb,
Croatia
Workshop on Small-Scale Accelerator Facilities,
Aghios Nikolaos, Crete, Greece, Sept. 7-8,2007
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Laboratory for Ion Beam Interactions
Duoplasmatron
1 MV Tandetron
Sputtering
6 MV EN Tandem
Alphatross
External beam
PIXE RBS
H.R. PIXE
TOF ERDA
Nuclear microprobe
Nuclear reactions
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• Negative ion sources

• Direct extraction duoplasmatron (H,D,O) -
  Tandetron
• Alphatros - RF with charge exchange (H, D, He)
  EN Tandem
• Sputtering ion source (H, Li, C, O, Si, Cl,
  I,...) EN Tandem, Tandetron (08)

Ruder Bokovic Institute, Zagreb, Croatia
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• Beam lines

• IAEA beam line - routine PIXE/RBS
• TOF ERDA
• Nuclear reactions chamber
• High res. PIXE, ion implantation
• Nuclear microprobe
• External beam PIXE

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• Microbeam scattering chamber

Spatial resolution 0.5 x 2 ?m (low current) 1 x
3 ?m (high current)
PIXE
Load lock
xyz rotation
STIM
ERDA
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Microprobe setup for PIXE, RBS, ERDA and NRA
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• Focusing system upgrades

• Insufficient and asymetric demagnification
• (only 11.3 in x)
• ME/q2 product only 7 mid energy light ions
• (e.g. 4 MeV 16O3)

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Ion microprobe applications Materials
modification
Important processes - creation of defects (el.
or nucl. stopping) - implantation of ions Low
energy heavier ions - Radiation damage (nuclear
stopping) - Ion implantation Swift heavy ions
- The highest energy transfer (el.
stopping) - Single ion tracks! (tens of
nm) Proton beam writing - High aspect
ratio - High resolution beam (Singapore) - 2D
(3D using different ranges)
35Cl ions in silicon
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• Why ion microprobe ? it is ideal radiation
  source

• X,Y (focusing and scanning)
• Z (ion range - p, ?, Li, C, O,..)

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a) Low energy heavier ions

• Importance of nuclear stopping
• creates complex (cluster) defects
• maximum at the end of range
• annealing required (for ion implantation)
• Applications to
• Structuring electronic defects
• Creation of nanocrystals (carbon)

430 keV protons
Number of vacancies per p 28 ! Number of
vacancies per O 2800 !
6 MeV O ions
Ruder Bokovic Institute, Zagreb, Croatia
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• Creation of position sensitive radiation sensors

4 MeV 16O
4 MeV 7Li
Si pin diodes are irradiated by different
fluences and different ions Graduated and
position dependent radiaton damage is produced
IBIC measurements
4.063 MeV 7Li 4 MeV 16O3
Ruder Bokovic Institute, Zagreb, Croatia
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• Ion implantation

ion beam implantation followed by thermal
annealing - one of the best techniques for
controlled nanocrystal fabrication
Two different annealing processes 1.
furnace annealing (FA) T 1000ºC 1h, heating
speed 600ºC/h 2. rapid thermal
annealing (RTA) T 1100ºC 180 s, heating time
90 s, cooling time 100 s

• 3.9 MeV a RBS on SiO2 implanted with 320 keV C

SiO2 D2 5
1016 at/cm2 D3 1 1017 at/cm2
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H

• IEE ERDA for H detection
• 6.5 MeV 16O2 dmax (SiO2) 700 nm
• significant difference in H concentration for
  RTA and FA samples
• this suggests that H from forming gas diffuses
  fast into the sample
• amount of H initially trapped is decreasing
  during long FA

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b) High energy (swift) heavy ions ion tracks

• The highest existing transfer of energy to
  material
• Formation of long ion tracks (tens of nm
  diameter)
• Control of hit position by heavy ion microprobe
  (as B. Fisher, GSI, Darmstadt)
• Direct formation of structures, or by subsequent
  etching

AFM picture of SrTiO3 surface after exposure of
28 MeV I ions under grazing angle (2)
Cooperation with University of Duisburg
35 MeV Cl ions on polycarbonate film
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c) Proton beam writing
In p-beam writing, the beam is scanned across a
resist material in a predetermined pattern, which
is subsequently developed to produce
three-dimensional structures.
- pioneered by the Centre for Ion Beam
Applications (CIBA) at the National University of
Singapore.
- focusing MeV ions to sub-100-nm dimensions

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a) Proton beam writing
The penetration depth of the proton beam depends
on its energy, and this feature has been used to
produce multilevel structures.
Microsized copy of Stonehenge fabricated by using
p-beam writing in SU8 resist. 500 keV for
fabricating the horizontal slabs and 2 MeV for
exposing the vertical supports, the complete
structure can be fabricated in one layer of
resist.
F. Watt et al., Materials Today 10 (2007) 20
Application areas photonics, microfluidic
devices, biostructures Materials PMMA, SU8,
silicon, porous Si (PL), HOPG (ferromagnetic
structures) 30-150 nC/mm2 (depending on resist
material)
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3. Ion microprobe applications - archeometry
(cultural heritage)

• PIXE (and RBS)
• Sampling is required, but very small fragments
  can be analyzed!
• Cross sections (paint layers, alloys, ceramics)
  determination of elemental distributions

Ruder Bokovic Institute, Zagreb, Croatia
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• The case of Apoxiomenos

• Found in 1996 near Loinj in Croatia, 45 m below
  sea surface between two rocks
• Analyses of state, construction, molding, organic
  material in sculpture
• X-ray
• PIXE, microprobe

Ruder Bokovic Institute, Zagreb, Croatia
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• The case of Apoxiomenos

PIXE (or XRF) analysis of surface was
missleading! (12 of Pb) microPIXE
analysis showed - surface enrichment of
Pb - Pb conc. inside 2 !!
Cu
SUS36/16 12 Pb 78Cu 8 Sn 1.1 Zn 1.5 Ni
2 MeV p
Pb-M
Sn-L
Cu was leached by seawater that explain increased
concentration of Pb at the surface --gt Sculpture
is of Greek origin
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• Analysis of metal threads

Analysis of metal threads of a 17th century
church textile using PIXE
The left lamina contains more copper, whereas the
two right ones are silver laminas.
Ruder Bokovic Institute, Zagreb, Croatia
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• The case of St. Marko church portal

• Second half of the 14th century soft sandstone
  material
• - damaged by water
  and air pollution

- microPIXE monitoring of stone cleaning and
conservation
Florentine method of cleaning and consolidation
by soaking the stone in ammonium carbonate and
barium hydroxide was used.
Portal sample P1
Ba and S concentration level variations with
depth have been determined in samples taken
from the portal after the treatment. In
addition, Ba depth profiles in sandstone treated
by three different ways were measured.
Sandstone sample treated in laboratory
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• Examples analysis of pigments

Elemental map obtained at the RBI ion microprobe

Analyis of micro-samples by optical microscopy
methods (at the CCI Lab)
Cromatographic analysis (CCI)
PIXE analysis (RBI)
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The authenticity of art objects
Lead white used since antiquity, only white used
in European paintings until the 19th century.
- In 19th century lead white (2PbCO3Pb(OH)2)
was replaced by zinc white ZnO and barium white
(BaSO4) The use of titanium white - maximum age
of the painting of about 100 years, as TiO2 was
discovered in 1908.
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Meister HGG (Hans Georg Geiger)
- 17th century cultural heritage in Croatia
minimal - Hans Georg Geiger was living and
working between 1641 and 1680 in Slovenia and
Croatia (Austrian-Hungarian Monarchy) - he left
32 paintings (half in Croatia) - most of his
preserved works has not been signed - almost all
paintings in churches
2D element distribution of the pigment cross
section sample taken from the red area of the
painting.
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S Pb Hg
Sample No1
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13th European Conference on X-ray
Spectrometry EXRS-2008 will be held in June
2008, Cavtat, Croatia