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Chemistry Nanochemistry ppt

introduction to nanochemistry seminar ppt and nanochemistry powerpoint presentation and nanochemistry ppt free download
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AbbieBenson,United States,Professional
Published Date:13-07-2017
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Nanochemistry Lecture 1 Dr Charu Arora, Associate Professor, Department of ChemistryNanostructuresNanoscience and nanotechnology • Nanoscience deals with the scientific study of objects with sizes in the 1 – 100 nm range in at least one dimension. • Nanotechnology deals with using objects in the same size range to develop products with possible practical application. It is usually based on nanoscience insights.Nanoscience and Nanochemistry • Nanoscience is interesting in part of course because it by definition is new. But a more profound and important reason is that it deals with objects which are only slightly larger than an atom. This means that the properties of the objects can be influenced by direct manifestations of quantum mechanics. • It is also possible that nanoscale objects do behave just like as expected from (semi)classical physics, but the downgrading in size opens up possible new applications.Research on nano• Nanotechnology is the creation of functional materials, devices, and systems through control of matter on the nanometer (1 to 100 nm) length scale and the exploitation of novel properties and phenomena developed at that scale. • A scientific and technical revolution has begun that is based upon the ability to systematically organize and manipulate matter on the nanometer length scale.Ancient nanotech. • It is interesting to note that there has been use of what now would definitely be called nanoscience much before the advent of the word. • - Vases used by old Greeks and RomansNanotechnology marketNanoscaleDefining Nanoscale Nano - Dwarf -6 -9 Nano size: 1 nm = 10 millimeter (mm) = 10 meter (m) nm Combination of atoms or molecules to form objects of nanometer scale Cross section of human hairCarbon nanostructuresImportance of nanoscale • The wavelike properties of electrons inside matter are influenced by variations on the nanometer scale. By patterning matter on the nanometer length, it is possible to vary fundamental properties of materials (for instance, melting temperature, magnetization, charge capacity) without changing the chemical composition. • The systematic organization of matter on the nanometer length scale is a key feature of biological systems. Nanotechnology promises to allow us to place artificial components and assemblies inside cells, and to make new materials using the self-assembly methods of nature. Importance of nanoscale • Nanoscale components have very high surface areas, making them ideal for use in composite materials, reacting systems, drug delivery, and energy storage. • The finite size of material entities, as compared to the molecular scale, determine an increase of the relative importance of surface tension and local electromagnetic effects, making nanostructured materials harder and less brittle. • The interaction wavelength scales of various external wave phenomena become comparable to the material entity size, making materials suitable for various opto-electronic applications. •Nano-materials: Used by humans for 100 of years, the beautiful ruby red color of some glass is due to gold Nano particles trapped in the glass (ceramic) matrix. •The decorative glaze known as luster. Ruby Red glass pot (entrapped with gold nanoparticles) What’s special with Nano? The properties of nanomaterials deviate from those of single crystals or polycrystals (bulk). For example, the fundamental properties like electronic, magnetic, optical, chemical and biological Surface properties: energy levels, electronic structure, and reactivity are different for nano materials. Exhibit size dependent properties, such as lower melting points, higher energy gaps etc. On the Surfaces and interfaces basics: Bulk. In bulk materials, only a Nano. In nanomaterials, large no. relatively small percentage of of atomic features near the atoms will be at or near a interface. surface or interface (like a crystal grain boundary). 15Nanostructured materials • Nanoparticles • Nanowires • Nanotubes • Nanorods • Nanoporous materials • Other structuresBulk and Nanoscale Density of states for 3D, 2D, 1D, 0D showing discretization of energy and discontinuity of DOSElectrons in nanoparticles as particle in a box modelEffects of Nano size • Properties depends on size, composition and structure • Nano size increases the surface area • Change in surface energy (higher) • Change in the electronic properties • Change in optical band gap • Change in electrical conductivity • Higher and specific catalytic activity • Change thermal and mechanical stabilities • Different melting and phase transition temperatures • Change in catalytic and chemical reactivitiesBulk and Nanoscale Bulk (eg. Gold) Nano (eg. Gold) 1. Lustrous–Shiny surface when 1. Vary in appearance depending on polished. size & shape of cluster. 2. Malleable–Can be hammered, 2. Are never gold in colour. bent or rolled→any desired shape. 3. Are found in a range of colours. 3. Ductile–Can be drawn out into 4. Are very good catalysts. wires 5. Are not “metals” but are 4. Yellow colour when in a mass semiconductors. 5. Heat & electricity conductor 6. Melts at relatively low temperature 6. High densities (940º C). o 7. High melting point (1080 C) 7. Size & Shape of the nanoparticles 8. Tough with high tensile strength determines the color. 9. Inert-unaffected by air and most 8. For example; Gold particles in reagents glass: 25 nm — Red reflected 50 nm — Green reflected (Unexpected visible properties & they are small enough to scatter visible light rather than absorb)