11/28/2011

1

Metallic bonding

11/28/2011

2

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

11/28/2011

3

Au

Ag

Specific heat 

color 

Properties vary with size

melting point 

Bandgap

conductivity 

11/28/2011

4

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

11/28/2011

5

11/28/2011

6

11/28/2011

7

MBE setup

11/28/2011

8

Physical vapour depositin

a) Electron beam evaporationb) Ion Plating Processc) Sputtering

torus‐shaped argon plasma

11/28/2011

9

11/28/2011

10

Layer by Layer deposition

Self organize on a substrate surface

Functionalization of NPs

11/28/2011

11

Carbon nanotubes

metallic

Semimetallicor semiconductor

Vertically aligned CNTs

11/28/2011

12

Functionalization of CNTs

Functionalization of CNTs

11/28/2011

13

Functionalization of CNTs

Fullerene

11/28/2011

14

Functionalization of Fullerene

SEM of TiO2

11/28/2011

15

TEM of TiO2

TEM of TiO2

11/28/2011

16

TEM of CuO

TEM of CuO