2 nd SASC Muharram, 1425 Jeddah, KSA

1. بسم الله الرحمن الرحيم Compositional Study of Different Currency Coins Using Non-Destructive Laser Induced Breakdown Spectroscopy 2nd SASC Muharram, 1425 Jeddah, KSA Zain Yamani, Ph.D. Physics Department KFUPM

2. Presentation plan • Introduction: What is LIBS? • Different physical methods for material analysis. • What is special about LIBS? • Compositional determination of coins using LIBS: • a- Experimental set-up • b- Results • c- Conclusions • Concluding remarks

3. Introduction LIBS: Laser Induced Breakdown Spectroscopy LIBS is an analytical method by which one can determine (qualitatively and quantitatively) the elemental composition of solid, liquid or gas samples. • LIBS • focused laser pulses • vaporize, atomize and excite the sample • plasma emission • collect, disperse and analyze light • atomic spectral lines determine the elemental composition

4. What other methods are used for elemental analysis

6. How does LIBS compare with other analytical methods? • Micro-LIBS • Portability • Rapid • NDT • Different types of samples • Little sample preparation • No (chemical) waste This is not to say that there are no complications in LIBS. Of course, there are!

7. What is LIBS used for? (applications, from the literature) • Environmental monitoring to measure soil contamination (Zolotovitskaya et al., 1997) • Detect toxic metals (Yamamoto et al., 1996; Buckley et al., 2000) • Study the chemical compositions in liquids (Yueh et al., 2002; Samek et al., 2000) • Study the chemical compositions in polymers (Sattmann et al., 1998) • In forensics and military applications (Kincade, 2003) • Biomedical studies of bones and teeth • Art restoration (or conservation), by analyzing pigments and/or precious and ancient metals (Anzano et al., 2002)

8. mirror prism collecting lens Nd-YAG 3rd harmonic sample dichroic mirror monochromator PDA Rotating sample holder personal computer LIBS for coin compositional determination Experimental set-up Movie

9. grating mirror mirror 1024 diodes PDA ~ optical multi-channel analyzer With a Photo-Diode Array (PDA), one can simultaneously detect the intensity of many “different” wavelengths.

10. LIBS for coin compositional determination Experimental Results • PDA Calibration • Apply LIBS to coins • Check repeatability • Look for coin signatures • Reliability (same results in different regions!!) • NDT

11. LIBS for coin compositional determination 10% iron in KBr (calibration pellet) http://physics.nist.gov/cgi-bin/AtData/lines_form Data: 4000-4400 Å

12. LIBS spectra for (solid) one side of a 25 Fils Bahrain coin and (dashed) the other side of the same coin. Notice how the spectra are almost identical!!

13. There are similarities between the three spectra; for example, all have Fe peaks (e.g., @ 4228 Å. The game token does not contain copper (e.g. @ 4180, 4275 & 4377 Å). The real currencies do contain copper!! LIBS spectra for (solid) a 10-Hallalah Saudi coin, (dashed) 20 cent Euro coin and (dotted) a game token, in the 4000-4425 Å region. The Euro coin does not have the 4201 & 4401Å Ni peaks. The game token has more iron and nickel than the other (real) currencies.

14. Common iron peaks (e.g. 5270 Å). The game token does not contain copper. The real currencies do contain copper!! (e.g. 5293 Å). The Euro coin does not have the Ni peaks. (e.g. 5475 Å). LIBS spectra for (solid) a 10-Hallalah Saudi coin, (dashed) 20 cent Euro coin and (dotted) a game token, in the 5250-5550 Å region. The results are consistent with that of the 4000-4400 Å region. It is difficult to distinguish between Saudi and Bahrani coins. They probably have very similar elemental composition.

15. (a) (b) Photographs of the four coins used in the experiments (a) before and (b) after 30 seconds of laser irradiation. The coins show no apparent destruction due to LIBS.

16. LIBS as NDT? Is LIBS absolutely NDT?

17. LIBS for coin compositional determination Conclusions • LIBS spectra are repeatable. • LIBS gives consistent/ reliable results in different regions. • Coins have iron. • Game token has no copper. • 20 cent Euro coin is nickel-free. • We can distinguish between “different” currencies using LIBS. • The spectra of the Saudi 10-Hallalah and the Bahrain 25 Fils are very similar. • At the macroscopic level, LIBS procedure can be NDT.

18. Good general references on LIBS Also, check Applied Optics vol 42 (30), Oct. 2003 (theme issue)

19. Concluding Remarks • LIBS is a very useful technique for the elemental analysis of material. • LIBS can be used for fast, precise, on-line, non-destructive testing of coins. • LIBS can be beneficial for the identification of currency and also for quality control in coins production. • LIBS applies to different types of material and is conducive to interdisciplinary research, a concept very beneficial for academic research in Saudi Arabia.

20. Further study: • both qualitative and quantitative. • different photon energy and laser pulse energy. • effect of optical alignment of beam with the sample, and optical alignment of beam with the detection system. • increase sensitivity by using gated ICCD. • study the effects of delayed time. • I would be happy to work with collaborators.

21. Acknowledgement The support of King Fahd University of Petroleum and Minerals is gratefully acknowledged. The encouragement of professor M.A. Gondal, as well as the assistance of Mr. Abdullah Baziyad and Mr. Abdullah Al-Zahrani, is deeply appreciated. I am thankful to Mr. Fuad Enaya for his help in preparing the presentation. Thank you for your attention

25. Complications in Using LIBS Sample matrix Morphology Power [energy per pulse & pulse width] dependence Atmosphere type and pressure Shot to shot energy fluctuation Depends on photon energy [esp. plasma absorption]