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.