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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 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. Ablation: \a-’blā-shən\ • Using a laser to vaporize material. What is nano? • Very small! • 1nm, is a nanometer = 10-9m. • Essentially, a billionth. • It takes up to 150,000 nanoparticles to be as wide as a human hair. 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 • 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. Two pulsed laser ablation *Sample alignment Nd:YAG laser *Copper Fiber 0.25 mm Excimer Laser *Optical Fiber *different materials used in current lab set-up. • Courtesy of YoungKyong Jo Courtesy of YoungKyong Jo • 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. • A plume of germanium is first created then the copper is ablated to create a larger second plume that will condense onto the first. Courtesy of YoungKyong Jo • This is all captured by an ICCD camera. An ICCD camera captures light as sensitive as a single photon….much better than my camera… http://www.canemco.com/catalog/grids/Quantifoils.htm http://www.gatan.com/resources/answers/Answer-10.php • 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. transmission electron microscope scanning electron microscopy http://www.nims.go.jp/htm21/MA/tem.jpg • 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. 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…. 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 Variables being tested • the time that the sample deposits on the collection grid • the time between the lasers being triggered Variables being tested • the laser energy being used • the amount of gas flowing into the chamber What are we doing? •Learning about experiment •Studying procedures •Running experiments using different variables 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. 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.” 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 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 Any questions?