Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Silver NanoparticlesSlide 8Slide 9Laboratory 04Light and Nanotechnology : How Do we “See” Something Too Small to See?1Objectives• Measure the width of a human hair using a laser pointer and diffraction.• Synthesize silver nanoparticles, and investigate how color is related to particles.2NanotechnologyNanotechnology is the technology for design, fabrication and manipulation of nanometre scale systems, in the scale of 1-100 nmHow Small is nano ?1 µm = one millionth of a meter1 nm = one billionth of a meter≈ 1/50,000 thickness of a hair!≈ a string of 3 atomsIf we shrunk all distances by 110,000,000,000 XThe sun and earth would be separated by 1 mA football field would be 1 nmHuman hair thickness ~ 50 µm110,000,000 km110 mHigh Aspect ratioWhy Nanomaterials ? Quantum EffectProperties of NanomaterialsEnhanced electrical and heat conductivity Increased strength, tensile properties Magnetic propertiesOptical properties – color changes with sizeSilver Nanoparticles•Size: 10nm-100nm•Chemical formula: Ag•Details: Silver nanoparticles are ultra fine particles of silver. They are ten to a hundred nanometers large, and differ from the bulk silver as they have different colors such as yellow, as opposed to the silver. •This is due to plasmon absorbance: Incident light rays create oscillation in free electrons on the surface of nanoparticles, causing them to absorb electromagnetic radiation, creating different colors reflected.Synthesis of Silver nanoparticles8Reduction methodAg + → Ag (Reducing agent NaBH4)Ag atoms will stick together to form small particles.Addition of citrate-Act as a buffer to control pHAct as a binding agent to limit the growing of nanoparticlsAddition of hydrogen peroxide-Act as a etching agent , remove silver atoms from less stable nanoparticles.Silver nanoprism is formed.Bromide is added to control the size of the nanoprisms.9Diffraction of light through a single slitw sin = n Ɵ λ tan = y / LƟWyLIn this lab, a variation of single slit diffraction is used to measure the width of a human hair; instead of a single slit in a
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