In-situ XRF analysis as a diagnostic analytical tool in the conservation field A.G. Karydas, V. Kantarelou • Nuclear Science and Instrumentation Laboratory, IAEA Laboratories, A-2444 Seibersdorf • Institute of Nuclear and Particle Physics, NCSR “Demokritos”, Aghia Paraskevi, Athens, Greece Andreas Karydas, ICTP, 14 th of July 2015
Outline and the PROMET analytical campaigns across the Mediterranean Outline 1. The PROMET project 2. The micro-XRF mobile instrumentation 2. Accuracy and pitfalls of micro-XRF analysis 3. PROMET campaigns: - Ancient Messene (2006) - Malta, Armoury Palace (2006) - Damascus National Museum (2007) - Numismatic Museum, Yarmouk University, Irbid, Jordan Andreas Karydas, ICTP, 14 th of July 2015
PROMET FP6:2005-2008 Aim: To develop Prototype innovative and advanced analytical methods to survey large collections of metal objects in- situ, making it possible to pinpoint conservation needs without any risk of damaging the artefacts Efficient, versatile and mobile analytical methodologies: Micro-XRF and Laser Induced Breakdown Spectroscopy LIBS related tasks were carried out by Prof. D. Anglos FORTH-IESL, Crete 24 partners , including Turkey, Syria, Jordan, Morocco, Italy, France, Spain, Czech Republic Coordinator: Prof. V. Argyropoulos (TEI, Athens) Andreas Karydas, ICTP, 14 th of July 2015
Demokritos objectives within PROMET: To develop, optimize and calibrate the analytical performance of an innovative portable micro-XRF spectrometer To develop and improve analysis procedures, protocols and the standardization of the method To apply the micro-XRF spectrometer for systematic technological and conservation related studies of museum metal collections at the Mediterranean region: • The study of the manufacture technology of metal alloys • Non – invasive characterization of corrosion products • Contribution to the assessment of innovative protective coatings Andreas Karydas, ICTP, 14 th of July 2015
μ-XRF spectrometer: Principle of operation X-ray tube X-Ray detector Sample Development and application of portable micro-XRF unit Focusing X-ray device: Polycapillary X-Ray lensy Customized design of ARTAX by Bruker Nano AXS Andreas Karydas, ICTP, 14 th of July 2015
Versatility: In-situ Micro-XRF analyses X-ray Detector Laboratory test of TEI coupon X-ray lens Laser pointer Headed Eagle lapis lazuli and gold 3000 B.C. Early Bronze Age Damascus National Mus eum, Syria, October 2007 Numismatic Museum of Yarmouk University Irbid, Nov. 2008 Andreas Karydas, ICTP, 14 th of July 2015
Pitfalls: Interference of XRF signal with diffraction peaks, QC/QA of micro-XRF data SBL 50kV, 600 A, 50s 5 10 SBLnorm_unfiltered_100 sec/600 A #1 SBL_filtered_(Ti+Co) Au #2 Au Au Au Diffraction peaks 4 4 10 10 Cu Bragg peaks Au Heterogeneity at the micro-scale 3 Au 10 Au Counts Counts 3 10 Definition of the scanning area Rh Ag Fe 2 10 that represents the alloy bulk Ag 2 10 composition 1 10 Cu 1 10 0 10 5 10 15 20 25 6 8 10 12 14 Energy (keV) Energy (keV) Alloys Filters/ Thickness (μm) Ti (23.6 ± 0.2) Co (17.7 ± 1.3) Pd (11.3 ± 0.3) Gold x x Silver x x x x Copper x
Analytical range using He atmoshpere Ceramic sample Helium No Helium 50kV, 600mA, 100s 1400 1200 Si K 1000 Counts 800 Ca 600 400 Al 200 1 2 3 4 Energy (keV) The improvement in the intensity of Al-K and Si-K characteristic X-ray lines is significant, 22 and 7.3 times, respectively.
Analytical performance: Elemental sensitivity Thin Targets ~ 50 μg/cm² 2 ) Sensitivity: cps/( g/cm Ni Fe Cu Ga V Co 10 Ge Cr Br Ca Pt Rb Se SrY K 600 μA W-Au Pb Nb Cl 50 kV 1 S Ag-Sn Si Al Ag 0.1 Sn K-sensitivities, He atmosphere K-sensitivities, No Helium 0.01 L-sensitivities, No Helium 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 Energy (keV)
Analytical performance: Spatial resolution Filtered_Ni (25 m) 100 Unfiltered 90 FWHM ( m) 80 70 60 50 40 30 0 5 10 15 20 25 Energy (keV)
1 I ( E ) G w I ( E ) T ( E ) ( E , E ) A ( E , E ) F dE f ( E ) ( E ) i k i i k i k i air k d k sin 1 Calibration methodology Andreas Karydas, ICTP, 14 th of July 2015
Experimental/simulated pure element thick/thin elemental intensities (a) 0 Thin targets 10 Intensity (cps/ A) -1 10 Theory (FPA) (K lines) Experimental (K lines) Theory (FPA) (L lines) Experimental (L lines) -2 10 0 2 4 6 8 10 12 14 16 Energy (KeV) Kantarelou et al ., XRS, 2015 Andreas Karydas, ICTP, 14 th of July 2015
Results of the fitting procedure Estimated Lens transmission efficiency 50 (c) Thick targets (K lines) 40 Thick targets (L lines) 1.0 (d) 30 Thin targets (K lines) (%) Deviation Thin targets (L lines) Transmission (a.u.) 20 0.8 10 0.6 0 -10 0.4 -20 -30 0.2 -40 -50 0.0 0 5 10 15 20 25 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Energy (KeV) Energy (keV) Kantarelou et al ., XRS, 2015 Andreas Karydas, ICTP, 14 th of July 2015
Accuracy/Quantification of CH related materials (b) 1.3 I Gold/Silver alloys (a) 1.2 J 620 K 1.1 3.0 1412 L Factor (K i ) Glasses 89 CNR91 1.0 BAM 2.5 CNR92 1831 Factor (K i ) 0.9 CNR152 a4 2.0 ABQAQ 0.8 c3 ABSBL d3 1.5 ABLLI 0.7 f3 ABKMF e3 1.0 0.6 4 6 8 10 12 14 16 18 20 22 24 26 28 Energy (keV) 0.5 0 2 4 6 8 10 12 14 16 18 20 2.4 K lines Energy (keV) L lines 2.2 Glasses mean value of K i 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0 2 4 6 8 10 12 14 16 18 Energy (keV) Andreas Karydas, ICTP, 14 th of July 2015
Assessment of micro-XRF analysis accuracy Validation with respect to Cu based RMs Micro-XRF (~50μm) Milli –XRF (3 mm) A. Heginbotham et al ., An Evaluation of Inter-Laboratory Reproducibility for Quantitative XRF of Historic Copper Alloys, Proceedings of the International Conference on Metal Conservation, METAL 2010, pp 178-188 , Edited by Paul Mardikian, Claudia Chemello, Cristopher Watters and Peter Hull, 11-15 October 2010, Charleston, South Carolina, USA Andreas Karydas, ICTP, 14 th of July 2015
Semi-QA and Diagnostic Micro-XRF Analysis Methodology: Variation of the K/L or L/M elemental intensity ratios in single spot, line or area scan measurements Filtered excitation Analysis of corroded area vs corrosion free area Line and area scans to obtain in reasonable measuring time (1x1 mm 2 , 50 μm step, 10s/step,~1.5h) intensity maps of the detected characteristic X-ray lines Andreas Karydas, ICTP, 14 th of July 2015
Semi-QA and Diagnostic Micro-XRF Analysis Results obtained: Identification of the spatial coexistence of different elements, fingerprints of certain corrosion products or of manufacture techniques. Estimation on a semi-quantitative basis of the elements enriched or depleted from the surface Rough estimation of the depths that a certain element is located, namely, on the surface, near surface (~2-10 μm) or below ~10 μm. Spatial distribution of individual elements Identification of the presence of certain minor to trace elements that may support provenance and manufacture studies of the metal Andreas Karydas, ICTP, 14 th of July 2015
Analysis of Copper coupon corrosion products Artificially and naturally aged bronze coupon: (Cu: 91.3%, Sn: 7.5%, Pb: 1.0%) # 9 Cu-K 5 #9 : green area 10 Sn-L+Ca-K # 47 Cu-K 4 10 #47: pale green area Counts CuEP 3 10 Cl Pile-ups Pb-L 2 Rh 10 Pb-L Sn-K Rh 1 10 0 10 4 8 12 16 20 24 Energy (keV) #47 #9 1.2 1.0 Intensity 0.8 0.6 Cl-K 0.4 50kV, 600μA, Cu-K 0.2 30s/step,0.1mm/step, I F 0.0 50 measurements 0 1 2 3 4 5 Position (mm)
Analysis of metal corrosion products Silver coupon (prepared-characterized by Prof. G. M. Ingo, A - Paratacamite Polytechnico of Milano) A – Green B - Chloroargyrite B - White C - Silver (oxide) C - Black Artificially 0.00 1.00 and naturally 0.25 0.75 aged silver C A u L coupon: - - 0.50 K g 0.50 A A - Green B - White Ag: 92% 5 10 Cu-K C - Black 0.75 0.25 D Cu: 6.5% Cu-K B 4 C 10 Ag-L Pb: 1.5% 1.00 0.00 Counts Cl 3 10 0.00 0.25 0.50 0.75 1.00 Fe + CuEP Ca Cl-K 2 10 5 10 B Cu-K Cu-K 50kV, 600μA, A 1 10 C 4 10 Ag-L Ag-K 30s/step, 0.1mm/step, Pb-L Pb-L Counts Cl-K 0 esc-Cu Pile-ups 10 3 10 Rh-K Ag-K Ca-K 2 3 4 5 6 7 8 9 10 Pb-L 50 measurements Energy (keV) 2 10 1 10 0 10 4 8 12 16 20 24 A.G. Karydas et al , PROMET Book, 2008 Energy (keV)
Damascus Archaeological museum: Analysis of silver tarnishing Silver Bowl 1400 -1300 BC Late Bronze Age Thickness of the layer: ~ 0.5 μm Black 5 10 Metal Cu Ag 4 10 Ag Au Cu Au 3 Counts Ca 10 Rh Cl Ag Au S 2 10 1 10 Black 5 10 0 10 5 10 15 20 25 Metal Energy (keV) Ag 4 10 Counts 3 Cl 10 S 2 10 1 10 0 10 1 2 3 4 5 Energy (keV) Tarnish: corrosion mainly caused by the sulfur in the air
PROMET, Damascus, Syria: Gilded Bronze figurines Late Bronze Age, 1400 B.C. Ugarit site: Issues addressed Manufacture technology (compositional analysis, raw materials ) Gilding technique Identification of corrosion products Kantarelou et al., JAAS, 2015 Baal Gods El God
Recommend
More recommend
