2.5. PIXE Analysis of Metals, Paper and other...
Transcript of 2.5. PIXE Analysis of Metals, Paper and other...
2.5. PIXE Analysis of Metals,
Paper and other Artifacts
Karomama, daughter of the Theban Priest Nimlot
of the southern empire. She married Takelat II
of the north cementing the union of the southern
and northern Egyptian empire.
Among the Egyptian antiquities in the Louvre is a statuette of
Queen Karomama, of the twenty-second dynasty. It was thickly
covered with green rust. The conservators suspected it was no
ordinary example of bronze and it was resolved to carefully
remove the coating. As the operation went on the character of
the metal changed. Finally it was discovered that the bronze
was damascened with gold and silver, and that much
ornamentation was spent over the royal robes. (Arthur Lee
1890) (report on original analysis of surface corrosion.)
The surface of Karomama
The microstructure of surface layers
Two faces of Egyptian egida
ca 500 BC, (Louvre, Paris)
Sacred Amon worshipper Karomama,
ca 820 BC - 22nd dynasty,
(Louvre, Paris)
Depth profiling of surface with high
energy proton PIXE techniques to
obtain, composition, structure and
corrosion properties
identification of original surface
below material and corrosion build-up
through Bronze disease. Bronze statuette, inlaid with gold,
silver, black a white paste (eyes)
Bronze Disease The environmental degradation of bronze artifacts is primarily
due to corrosion processes of the metal components of the
alloy.
Copper reacts at room temperature with oxygen in air
producing oxides, which in the presence of SO2 (a gaseous
pollutant) are transformed into brochantite:
(CuSO4)•3Cu(OH)2.
Copper is also capable of reacting with CO2, an air
component, producing compounds with the typical colors of
degraded copper and bronze: malachite (green):
CuCO3•Cu(OH)2 and azurite (blue): 2CuCO3•Cu(OH)2.
Tin, reacting with oxygen, transforms into SnO2, whereas
lead, following reaction with CO2 in the air, gives rise to lead
carbonate PbCO3.
The corrosion proceeds further through pores and cracks
present in such patina and may be faster in the presence of
hydrochloric acid HCl. The chloride ions Cl-, released by the
acid, replace OH- ions present in the patina, giving rise to
metal chlorides which are soluble and hygroscopic and are
washed away.
Surface Deterioration of Bronze PIXE scan: 50x150μm2
• 0.37 % chlorine concentration
15μm into corrosion layer
• 0.12 % chlorine concentration
>50μm depth
Cu
Sn Ni
Pb
Corrosion Copper chlorid
Corrosion by extensive exposure to
aqueous chloride (NaCl) solution
Use of portable X-ray fluorescence instrument for bulk alloy analysis on low
corroded indoor bronzes; D. Šatović, V. Desnica, S. Fazinić, Spectrochimica
Acta Part B 89 (2013) 7–13
PIXE scan of sample cross section
clean 14 days 26 days
Photograph and micrograph of bronze sample 26 days 14 days
Karomama Restored
Metal Soldering
Myrtle wreath, gold,
Greek/Macedonian; 4th century BC
Analysis of soldering technique for
conservation & reconstruction
Main tube
of diadem
Gold leaf
of diadem Gold-copper
alloy
Au Au
Fe
Au Ag
Au
Au
Au
Ag
Au
Au
Cu
Cu
Ag
Au
Zr
Zr
Ag Zr
Au
J. Maish, JAIC 34 (1995) 113-127
Zr
The Achaemenid Pendant
4th century BC
Excavated from Iranian tomb
motif represents deity with two
birds flying in front. 28 old balls
soldered to tubes bent from thin
old sheets and soldered together.
G. Dermortier, Nucl. Instr. Method. B 14 (1986) 152 - 155
The Achaemenid هخامنشیان empire was
founded by Cyrus the Great in 559 BC
PIXE view of the Achemenide pendant
Relief work with fairly constant Au and A content; Fe shows
at joints and solder points, tube shows high Cu concentration
PIXE analysis of solder joints
A D C B
A D C B
A
D C
B
Solder connections clearly recognizable; composition of each
solder alloy reveals ancient soldering technique:
• Brazing with Cu-Ag-Cu alloy at point A,B happened at T800oC with slow
cooling.
• At C joint by local fusion of elements at T1000oC, reduction of less noble
elements
• at D copper diffusion bonding at T900oC, Cu diffuses into Au at T<Au
melting point, providing a very hard bond.
Cadmium & Forgery
supposedly from the 1st century AD. The three center
medallions show images of Vespasian, Titus, Domitian.
The Vespasian
necklace,
Cadmium in
ancient metalwork
is often interpreted
as strong indication
for modern forgery!
Yet, it occurs naturally
in zinc and lead ores
as orange yellow
coating (CdS) on the
zinc minerals.
Detailed Analysis of medallion Systematic micro-beam analysis
Reveals Cd enrichment at solder points
G. Dermortier & T. Hackens, Nucl. Instr. Meth. 197 (1982) 223-226
Experimental Arrangement for mapping out silver-copper solder to investigate cadmium correlation
Necklace
solder
Modern
solder
Micro-beam analysis of Cu-Ag-Au solder
Ternary diagram gives indication for Cd in ore material. Modern solders
show anti-correlation between Cadmium and Copper. This solder shows
correlation between Cd and Cu which indicates ancient origin!
Nature of ink and pigments with PIXE
PIXE has developed into a major analytical tool
(like X-ray fluorescence) to investigate ink and
pigments in old manuscripts and parchments.
The main goal is to understand ancient production
processes and the associated chemical techniques.
Further goals are:
• to identify authors and artists of ancient paintings
• to detect and identify forgeries.
gallic acid + FeSO4.7H2O + water→ iron-gall ink
Nature of ink and pigments with PIXE
Ritualistic talmudic texts had to be
written with special kosher ink. During
the 12th and 13th century a bitter
dispute between talmudic scholars
about the question which kind of ink
does really fulfill the requirements:
• indian ink used by French Jews
• gall ink used by German Jews
A decision was made not to accept
iron- but only copper vitriol since the
last 6th century entry into the Talmud
(summary of ancient Rabbi decisions)
mentioned gall-apples & copper vitriol.
PIXE analysis of parchment
shows strong iron content, in
disobedience of the decision!
Ink and paper of the Gutenberg bible
Analysis of many single letters showed
that ink had unusually high copper (Cu),
nickel (Ni), and lead (Pb) concentration
high printing quality!
Deep black ink after 500 years
R. Eldred et al., Nucl. Instr. Meth. B3 (1984) 579-583
Medieval Book of Hours
Bone white calcium for
parchment preparation Gold leaf for
head lettering
Blue pigment is Azurite, a
mineral copper carbonate
2 CuCO3 · Cu(OH)2
Black ink is Ferro-Gallic
ink with high Fe and Zn
content.
Red ink is based on the
pigment Vermillion HgS.
Letter identification through PIXE
Use of the lateral resolution of
a microprobe permits the study
of small details in the material.
For example PIXE analysis of
paper content combined with
statistical methods leads to the
identification of faint letters.
Greek handwriting of
letter on papyrus
photograph
PIXE image
G. Löwestamm & E. Swietlicki, Nucl. Instr. Meth. B43 (1989) 104
Comparative dating Galileo dated his writings only infrequently, PIXE analysis of ink
provides clues toward development of his thought and ideas by identifying
the sequence of notes..
Un-dated manuscript can be
Placed in time and context by
PIXE analysis of ink.
Hand-made ink showed
differences from batch to batch
Galileo's writings: chronology by PIXE; L. Giuntini, F. Lucarelli,
P.A. Mandò, W. Hooper, P.H. Barker, NIM B95 (1995) 389-392
Further results from PIXE analysis of inks in Galileo’s notes on
motion; P. Del Carmine, L. Giuntini , W. Hooper, F. Lucarelli, P.A.
Mandi, NIM B 113 (1996) 354-358
Change in medieval ink composition
Recent applications to the study of ancient inks with external-PIXE facility; F. Lucarelli , RA. Mando;
NIM B 109/110 (1996) 644-652
1607
1425
Summary PIXE PIXE is very similar to XRF, the mechanism for exciting the
atoms to generate the characteristic X-rays is not based on X-
ray irradiation of the sample but on the bombardment with high
energy particles – typically protons up to 10 MeV. The
disadvantage to XRF is, that only small areas can be studied to
small depths. For a global study (~cm2 areas) of the chemical
characteristic of a sample XRF is the better method. For the
study of m2 areas PIXE is the superior approach. Its large
advantage to XRF is that two or three dimensional images of the
elemental distribution In the sample can be produced with high
spatial resolution. Depth profiling is possible within a fairly
limited depth range of 0.1mm only. Like in XRF studies the K-
and L-transitions of the low to high Z elements are the main
signatures.