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Nanotechnology

Explore the definition and physical properties of nano crystals, including quantum confinement effects, size-dependent properties, and self-assembly behaviors. Learn about their unique characteristics and applications in various fields.

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Nanotechnology

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  1. Nanotechnology • Prof. Dr. S. Taha • Physics department • Vice Dean for Postgraduate • Studies and Research Affairs • Faculty of Science • Fayoum university • Egypt

  2. 1- definition of nano Particles . • A nano cluster is a tiny chunk of the bulk measuring a few nanometers with a Finite number of atoms in it. • 2- Physical Properties of Nanocrystals . • a- The electronic Structure of a nano crystal Critically depends on its Size . • The electronic level are not Continuous as in bulk materials , but discrete , due to the confinement of the electron wave - function because of the Physical dimensions of the Particles . This Phenomenon is Called quantum confinement, therefore , nanocrystals are also Known as quantum dots.

  3. b- The average electronic energy level Spacing of Successive quantum levels , Known as the so-Called Kubo gap , is given by • n3/ EF4 = δ • c- The resultant discreteness of energy levels . ( the nano crystals Can be discretely charged with electrons ) . ( i . e ) nano crystal Carrying an extra electrons can exhibit Properties different from those of a neutral species also brings about fundamental changes in the characteristic Spectral features of the nano particles , especially those related to the valence band .

  4. 3- The nano Sized clusters display a remarkable tendency to remain Single – Crystalline and hence are also called nano crystals . In addition , nano crystals Possess a high surface area : A great fraction of atoms in nanocrystal is on its surface . • The nano crystals is their Size – dependent Properties ( i . e ) the electronic , magnetic , and optical Properties of a nano crystal depend on its size ( quantum size effects ) .

  5. 4- a - The nano crystals akin to covalent systems Self-assemble into ordered arrays in one , two and three dimensions under the right conditions . • b- Lattices of nano crystals consist of interacting nano crystals and may exhibit novel Properties arising out of such interaction . • c- Thus , the ability to engineer such assemblies extends the reach of current lattices of nano crystals and holds promise for a new generation of electronics of the nanoworld .

  6. 5- size control • 6- Shape control .

  7. 7- Example CNT .

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