1. Core-Shell Nanoparticle Generation Using Laser Ablation Vanessa Coronado, Westside High School, Houston ISD Dr. Sy-Bor Wen/ Assistant Professor and YoungKyong Jo/ Ph.D. student Dept. of Mechanical Engineering http://www.istm.cnr.it/~ponti/NJC06.html

2. Dr. Sy-Bor Wen, Department of Mechanical Engineering Ph.D. in Mechanical Engineering @ University of California at Berkeley, CA M.S. and B.S. in Mechanical Engineering @ National Taiwan University, Taipei, Taiwan Working on using lasers to ablate germanium and copper and condense them together to form a nanoparticle core-shell material that has superior optical and electromagnetic properties.

3. Ablation: \a-’blā-shən\ Using a laser to vaporize material.

4. What is nano? Very small! 1nm, is a nanometer = 10 -9 m. Essentially, a billionth. It takes up to 150,000 nanoparticles to be as wide as a human hair.

5. Lasers being used Excimer laser – class IV laser (short for 'excited dimer‘) 193 nm = UV light Nd: YAG laser – class IV laser (neodymium-doped yttrium aluminum garnet) 532 nm= green light en.wikipedia.org/wiki/Nd-YAG_laser

6. The laser light is fed through a series of mirrors and lenses to a closed chamber that has the samples of copper and germanium inside.

7. Two pulsed laser ablation Courtesy of YoungKyong Jo *Sample alignment *Copper Fiber 0.25 mm *Optical Fiber Excimer Laser Nd:YAG laser *different materials used in current lab set-up.

8. The excimer laser is triggered first to ablate the germanium and a fraction of a second later the Nd: YAG laser will be triggered to ablate the copper sample. Courtesy of YoungKyong Jo

9. A plume of germanium is first created then the copper is ablated to create a larger second plume that will condense onto the first. This is all captured by an ICCD camera. An ICCD camera captures light as sensitive as a single photon….much better than my camera… Courtesy of YoungKyong Jo

10. Once the particles have condensed and formed, they deposit on the inside of the chamber onto a collection plate strategically placed inside of the chamber. This occurs over a period of time that varies up to 2 hours. http://www.canemco.com/catalog/grids/Quantifoils.htmhttp://www.gatan.com/resources/answers/Answer-10.php

11. The particles are then taken for imaging using a SEM- scanning electron microscope and a TEM- transmission electron microscope to see if core-shell nanoparticles were created. http://www.nims.go.jp/htm21/MA/tem.jpg scanning electron microscopy transmission electron microscope

12. Possible applications of nanoparticles Biomedical uses – cancer cell eradication that targets only malignant cells Better catalyst Creates stronger magnetic field for use in electronics Makes stronger, lighter composite materials ? ….we don’t know what else….

13. Variables being tested the position within the chamber that the sample is being collected from. the gas that is within the chamber is variably argon or helium. in air in argon

14. Variables being tested the time that the sample deposits on the collection grid the time between the lasers being triggered

15. Variables being tested the laser energy being used the amount of gas flowing into the chamber

16. What are we doing? Learning about experiment Studying procedures Running experiments using different variables

17. In summary…. 2 lasers ablate germanium and copper a fraction of a second apart Second material condenses onto first to form core-shell particle Particles deposit over time and are sent to a SEM and/or a TEM If the particle is a core-shell particle…party…. then determine the properties of it.

18. How will this translate to the physics classroom? Not sure yet…but somewhere along the lines of…(get it…it’s a little laser joke)… Supporting TEK 8: “The student knows the characteristics and behavior of waves.” and/or Supporting TEK 9b: “the student is expected to explain the line spectra from different gas-discharge tubes.”

19. What might this look like? Using classroom grade lasers coupled with mirrors and lenses to discover properties of light and waves Use spectrum tubes to discover the differences between colors of light and what makes them unique. http://webapps.lsa.umich.edu/physics/demolab/controls/ima gedemosm.aspx?picid=600

20. Acknowledgements Texas A&M National Science Foundation E3 RET Program coordinators Mechanical Engineering Dept Dr Sy-Bor Wen and his team And viewers like you

21. Any questions?