Post on 20-Aug-2020
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Metallic bonding
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Metallic bonding
size‐dependency on the optical properties
The size‐dependency on the optical properties of CdSe nanocrystals. With decreasing size, the fluorescence peak is shifted to shorter wavelengths
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Au
Ag
Specific heat
color
Properties vary with size
melting point
Bandgap
conductivity
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Density of states (DOS) for electrons in bulk semiconductors (3‐D, blue), quantum wells(2‐D, red), quantum wires (1‐D, green), and quantum dots (0‐D, black).( , ), q ( , g ), q ( , )
Repeat 24 times
Nanoscale = High Ratio of Surface Area to Vol.Nanoscale = High Ratio of Surface Area to Vol.
For example, 5 cubic centimeters For example, 5 cubic centimeters –– about 1.7 cm per side about 1.7 cm per side –– of of material divided 24 times will produce 1 nanometer cubes and material divided 24 times will produce 1 nanometer cubes and spread in a single layer could cover a football fieldspread in a single layer could cover a football field
Source: Clayton Teague, NNI
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MBE setup
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Physical vapour depositin
a) Electron beam evaporationb) Ion Plating Processc) Sputtering
torus‐shaped argon plasma
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Layer by Layer deposition
Self organize on a substrate surface
Functionalization of NPs
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Carbon nanotubes
metallic
Semimetallicor semiconductor
Vertically aligned CNTs
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Functionalization of CNTs
Functionalization of CNTs
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Functionalization of CNTs
Fullerene
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Functionalization of Fullerene
SEM of TiO2
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TEM of TiO2
TEM of TiO2
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TEM of CuO
TEM of CuO