Yin handout - The Nanoscale Perspective Overview of...

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1 Overview of Nanotechnology BME 140 Frank Yin October 27, 2010 Content courtesy of: Younan Xia - BME Sam Wickline - WUSM The Nanoscale Perspective nm 100 10 7 10 7 People are 10,000,000 times smaller than the world. A nanoscale object, having a diameter of 100 nm, is 10,000,000 times smaller than people. Nanometer in Context Viruses (0.01-0.1 microns) Microprocessors (0.1-1.0 microns) Pin Head (1,000 microns) Bacteria (3-5 microns) Fungal Spores (5-30 microns) Dust, hair (10-100 microns) Why is Size Important ? Nanoparticles outperform microparticles simply due to increased surface area Fabricate particle - chemistry Steps in Making Functional Nanoparticles Functionalize it – chemistry/biology Deliver payload - interdisciplinary Hydrophobicity/hydrophilicity Nanotechnology Chemistry Polymerization Cross-linking Crystal structure Galvanic replacement reaction
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2 Younan Xia – chemical/crystal modification Two Approaches for Making Nanoparticles Sam Wickline – emulsification Cathedral Windows and the Lycurgus Cup Xia Lab Approach – gold nanocages Ag What is the origin of the color? Answer: ``surface plasmons’’ Ionic (not to scale) • A SP is a natural oscillation of the electron gas near the surface of, e.g. a gold nanosphere . . • SP frequency depends on the dielectric function and the shape and size of the nanoparticle . electron cloud Ionic background Electron cloud oscillates with frequency of SP; ions provide restoring force. Gold Nanoparticles and S urface P lasmon R esonance Gold colloids by Michael Faraday (1856) displayed at the Faraday Museum in London Scattering Absorption Extinction ( Abs. + Sca. ) Cross-section (10 -15 m 2 ) 50 nm Wavelength (nm) Optical Coefficient (a.u.) Smaller particles cause more red shift SPR of Different Geometries • Sharper corners cause more peaks
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This note was uploaded on 02/14/2012 for the course NUBITRY 3304 taught by Professor Various during the Spring '01 term at Albertus Magnus.

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Yin handout - The Nanoscale Perspective Overview of...

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