2.6. 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 was 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 layersTwo faces of Egyptian egidaca 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. Bronze statuette, inlaid with gold,

silver, black a white paste (eyes)

Surface Deterioration of BronzePIXE scan: 50x150μm2

• 0.37 % chlorine concentration 15μm into corrosion layer

• 0.12 % chlorine concentration >50μm depth

Cu

SnNi

Pb

Corrosion ⇒ Copper chlorid

Metal Soldering

Myrtle wreath, gold, Greek/Macedonian; 4th century BC

Analysis of soldering technique for conservation & reconstruction

Main tube of diadem

Gold leafof diadem Gold-copper

alloy

AuAu

Fe

AuAg

Au

Au

Au

Ag

Au

Au

Cu

Cu

Ag

Au

Zr

Zr

AgZr

Au

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, Bucl. Instr. Method. B 14 (1986) 152 - 155

The Achaemenid هخامنشيان 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 showsat joints and solder points, tube shows high Cu concentration

PIXE analysis of solder joints

gold

silver

copper

A DCB

A DCB

A

DC

B

Solder connections clearly recognizable; composition of eachsolder alloy reveals ancient soldering technique: • Brazing with Cu-Ag-Cu alloy at point A,B happened at T≈800oC with slow

cooling. • At C joint by local fusion of elements at T≈1000oC, reduction of less noble

elements• at D copper diffusion bonding at T≈900oC, Cu diffuses into Au at T<Au

melting point providing very hard bond.

Cadmium and Forgery

supposedly from the 1st century AD. The three center medallions show images of Vespasian, Titus, Domitian.

The Vespasian necklace,

Cadmium in ancient metalwork indicates

forgery!

Detailed Analysis of medallionSystematic micro-beam analysis

Reveals Cd enrichment at solder points

G. Dermortier & T. Hackens, Nucl. Instr. Meth. 197 (1982) 223-226

Experimental Arrangement

Mapping out silver-copper solder material

Micro-beam analysis of Cu-Ag-Au solder

However, Cd can be in ore material. Modern solders show anti-correlation between Cadmium and Copper. This solder shows correlation between Cd and Cu which indicates ancient origin!

Authenticy check for ship wreck coins

Nuestra Senora de Atocha

Treasures from the Atocha

Doubts about the authenticy of some of the “Atocha Escudos” on the market

Analysis of Spanish Escudos18th century escudo18th century escudo fake

Au Ag Fe Cuescudo 1

escudo 2escudo 3

escudo 4suspect coin

0102030405060708090

100

cont

ent [

%]

metal

coin

s

metal content of Spanish Escudo

escudo 1escudo 2escudo 3escudo 4suspect coin

metal content of Spanish Escudo

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

escudo 1 escudo 2 escudo 3 escudo 4 suspect coin

coin

cont

ent

[%] Cu

FeAgAu

Suspect coin hasconsiderably higherAu content and lessAg content thanSpanish Escudo

Nature of ink and pigments with PIXEPIXE 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 productionprocesses 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 PIXERitualistic talmudic texts had to be written with special ink. During the 12th and 13th century a bitter dispute between talmudic scholars about the question which kind of ink does really fulfill the ritualistic requirements:• indian ink used by French Jews• gall ink used by German JewsA 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!

Trionfo d’Amore Botticelli Drawing

The drawingis attributed to Botticellithe author of the incipit isunknown!

Petrach manuscript, Biblioteca Classense Ravenna, Fiesole

Pigment analysis with PIXE todetermine the technique and origin of paint.

PIXE analysis of Trionfo d’amoreBook holder construction to focus beam onto the seriesof pre-selected points in the drawing.

Paint analysis• The results showed that ochres

with addition of a lead base pigment, were used to obtain the brown colour.

• Iron-gall ink was used to trace the drawing.

• Lead point was used in the preparation of the drawing.

• It was not possible to identify the Lilac pigment used.

• The blue colour of the sky is a lead based pigment deposited on top of an underlying mixtureof blue pigments.

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

Letter identification through PIXEUse 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 ofletter χ on papyrus

photograph

PIXE image

G. Löwestamm & E. Swietlicki, Nucl. Instr. Meth. B43 (1989) 104

Comparative datingGalileo dated his writings only infrequently, PIXE analysis of inkMay provide clues toward development of thought and ideas. Un-dated manuscript can bePlaced in time and context byPIXE analysis of ink.

Hand-made ink showed differences from batch to batch

Summary PIXEPIXE 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 mm2 to mm2 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 withhigh 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.