1. Biomedical Applications of Plasma Spectroscopy: A Preliminary Study Dr. Unnikrishnan V. K. Associate Professor Department of Atomic and Molecular Physics Manipal University

2. Out line ۩ Introduction. ۩ Laser Induced Breakdown Spectroscopy (LIBS) Technique – A tool for trace element analysis. ۩ Objectives of the programme. ۩ Methodology. ۩ Preliminary studies on LIBS. ۩ References.

3. Laser-Matter Interaction Weakly ionized plasma Highly ionized plasma < 10 % very high Laser pulse intensity > Binding Energy of the electron Laser Beam Atoms Ions Free electrons Plasma characterization: Degree of Ionization

4. Laser Induced Breakdown Spectroscopy (LIBS) - Spectroscopic analysis of elemental emission from a Plasma created using laser from any sample. - Developed rapidly as a versatile analytical tool over the past two decades. - Appealing technique compared with many other types of elemental analysis because of its simplicity. - Fast Multi-elemental analysis in short time (few seconds). - Spatial discrimination at few microns apart; Micro analysis. - Analysis of the surface with out damage to body of the sample. Department of Chemistry, Changwon University, Changwon, Kyungnam, Korea

5. LIBS spectrum of a molten glass Jong-IL Yun et al, Vol 56, 437-448, Applied Spectroscopy, 2002

6. Importance of the Study Well being of all living things  environmental factors, food habits, life style etc. Society needs, technology development etc. Control of individual beings Trace Elements Essential for health at trace levels Harmful at larger concentrations Que: Trace element detection ??Ans: LIBS Technique

7. Methodology Design and Development of proposed LIBS set-up. The main components of a LIBS set-up are (1)Pulsed laser : generates the powerful optical pulses to form plasma (2)Light focusing system: mirrors, lenses etc. that directs and focuses the laser pulse on the sample. (3)Sample holder. (4)Light collection system: lens, mirror, fiber optic etc. that collects the plasma and transports to the detection system. (5)Detector: will disperse and record the light. (6)Computer: store the spectrum.

8. Laser: Nd-YAG 3 rd harmonic 355nm. Energy = 100mJ, Repetition Rate = 10 Hz, Pulse width = 6 ns, Peak power = 16.7 MW Pulsed Laser High resolution Detector Computer Delay Generator Optics: Focusing system Optics: Collecting system Sample Optics: Focus & Collection Lens, Prisms, Mirrors, Filters, Iris, Optical fiber (50 µm). Detector: Michelle Spectrograph-ICCD High spectral resolution, Broad collection range, Sensitive, Delay generator embedded. LIBS Schematic.

9. Calibration of Detection System. Wavelength Calibration Intensity Calibration National Institute of Standards and Technology (NIST) certified Mercury-Argon lamp National Institute of Standards and Technology (NIST) certified Deuterium-Quartz- Tungsten- Halogen lamp - ensure the measurement accuracy and ability to carry out meaningful analysis of acquired spectra from samples. Calibration over a wide range i.e. 200-975 nm

10. 1 ns10 ns100 ns1 µs10 µsec100 µsec Laser pulse Optical signal intensity Decay time after pulse incident on the target Detector Plasma continuum Timing considerations. Goal of LIBS technique: to measure an optically thin plasma whose elemental composition is the same as that of the sample

11. Nd-YAG laser (355nm) Pellin Broca Prism 355 mirror Beam Splitter 20/80 Lens Neutral Density Filter Beam Dump Vaccum Chamber Optical Fiber Computer Sample High resolution Spectrograph-ICCD system- Michelle Signal Collector Motorized horizondal/verical translation stages Setting up of a sensitive LIBS system

13. Vs Parameter Spectrograph-ICCD system Old Wavelength Range (nm)200-450 Spectral resolution (nm)0.4 GratingDiffraction Focal Length (mm)150 Slit width (µm)100 Active pixels (horizontal x vertical ) 1024 x 128 CouplingLenses New 200-975 0.05 Echelle 195 10 1024 x 1024 Fiber optic cable

14. 435.8nm Spectral resolution = 0.06 nm Spectral resolution = 0.74 nm Vs contd..

16. Region 1 Region 2 Region 3 Hard tissue Osteotome

20. References  Handbook of Laser-Induced Breakdown Spectroscopy by David A. Cremers and Leon J. Radziemski, 2006.  D. R. Alexander et al, “Environmental monitoring of soil contaminated with heavy metals using Laser-Induced Breakdown Spectroscopy ”, IEEE, 1994.  Karen Y. Yamamoto et al, “Detection of metals in the environment using a portable Laser-Induced Breakdown Spectroscopy instrument”, Applied Spectroscopy, 1996.  Russell S. Harmon et al, “Laser-Induced Breakdown Spectroscopy- An emerging chemical sensor technology for real-time field portable, geochemical, mineralogical and environmental applications”, Applied Geochemistry, 2006. Acknowledgement This research work is supported by Board of Research in Nuclear Sciences (BRNS).