بسم الله الرحمن الرحيم
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بسم الله الرحمن الرحيم. Compositional Study of Different Currency Coins Using Non-Destructive Laser Induced Breakdown Spectroscopy. 2 nd SASC Muharram, 1425 Jeddah, KSA. Zain Yamani, Ph.D. Physics Department KFUPM. Presentation plan. Introduction: What is LIBS?

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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


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


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



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!


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)


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


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.


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


LIBS for coin compositional determination

10% iron in KBr (calibration pellet)

http://physics.nist.gov/cgi-bin/AtData/lines_form

Data: 4000-4400 Å


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!!


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.


Common iron peaks (e.g. 5270 Å). example, all have Fe peaks (e.g., @ 4228 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.


(a) example, all have Fe peaks (e.g., @ 4228 Å.

(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.


LIBS as NDT? example, all have Fe peaks (e.g., @ 4228 Å.

Is LIBS absolutely NDT?


LIBS for coin compositional determination example, all have Fe peaks (e.g., @ 4228 Å.

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.


Good general references on LIBS example, all have Fe peaks (e.g., @ 4228 Å.

Also, check Applied Optics vol 42 (30), Oct. 2003 (theme issue)


Concluding Remarks example, all have Fe peaks (e.g., @ 4228 Å.

  • 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.


  • Further study: example, all have Fe peaks (e.g., @ 4228 Å.

    • 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.


  • Acknowledgement example, all have Fe peaks (e.g., @ 4228 Å.

    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


    Complications in Using LIBS example, all have Fe peaks (e.g., @ 4228 Å.

    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]