Conventional Properties

Quantum Size Effects

A chemist likes to keep track of material in grams or in moles, where a 1 mole = 6 x 1023 atoms

But how many atoms do you really need …

– for gold to become gold-colored ?

– for iron to become magnetic ?

– for water to flow like a liquid ?

1 < ? < 6 x 1023

Cobalt at the NanoscaleREPORTS

Colloidal Nanocrystal Shapeand Size Control: The Case of

CobaltVictor F. Puntes, * Kannan M. Krishnan, A. Paul Alivisatos

We show that a relatively simple approach for controlling the colloidal synthesis of anisotropic cadmium selenide semiconductor nanorods can be extended to the size-controlled preparation of magnetic cobalt nanorods as well as spher- ically shaped nanocrystals. This approach helps define a minimum feature set needed to separately control the sizes and shapes of nanocrystals. The resulting cobalt nanocrystals produce interesting two- and three-dimensional super- structures, including ribbons of nanorods.

IBM Research, 1992

Copper at the Nanoscale

One Atom “Trapped” Electrons

1 nanometer = 1 nm

giga

mega

kilo

milli

micro

nano

pico

1,000,000,000

1,000,000

1,000

1

0.001

0.000,001

0.000,000,001

0.000,000,000,001

meter

meter

meter

meter

meter

meter

meter

meter

Factors of One Thousand

meter =

meter =

meter =

meter =

meter =

meter =

meter =

meter =smaller

than atoms

distance to moon

you and me

nanoscience

U.S.A.

U.C.I.

pencil lead

blood cell

Size and Scale

1 nm = 0.000000001 m

10 um = 0.00001 m1 km = 1000 m

0.1 m

10 Mm = 10,000,000 m

Factors of 10,000

Conventional Properties

Al Si P ArCl

C

He

NeN FO

Cr Fe Co Ni CuTi

Pt Au

Nb Pd Ag

H

I Xe

Pb Bi

Ge AsGa KrBr83.80

131.29

4.0026

20.18014.007

39.94835.453

18.99815.99912.01

26.982 28.086 30.974

69.723 72.61 74.922 79.904

126.90

207.2 208.98

58.933 58.693 63.546

1.0079

47.867 51.996 55.845

92.906 106.42 107.87

195.08 196.97

GROUP

1

2

3

4

5

6

2

107

1817

98

36

54

16

13 14 15

28 29 31 32 33 35

5346 47

78 79 83

1

22 24 26 27

41

HYDROGEN

NIOBIUM

TITANIUM CHROMIUM COBAL TIRON

HELIUM

NEONNITROGEN FLUORINEOXYGENCARBON

ARGONCHLORINEALUMINIUM SILICON PHOSPHORUS

KR YPT ONNICKEL COPPER GALLIUM GERMANIUM ARSENIC BROMINE

XENONIODINEPALLADIUM SIL VER

PLA TINUM GOLD LEAD BISMUTH

11

13 14 15 16 17

181

54 6 8 9 10

NanoPeriodic Table – Under construction

Quantum Size Effects

A chemist likes to keep track of material in grams or in “moles”, where a mole equals 6 x 1023 atoms

But how many atoms do you really need …

– for gold to become gold-colored ?

– for iron to become magnetic ?

– for water to flow like a liquid ?

1 < ? < 6 x 1023

What’s the Difference?

“Quantized” Energy Levels

only certain properties are allowed at each size

E = hf = hc/

Energy Quantization

What’s the Difference?

Only certain energies are allowed: E = hf = hc/, where is a wavelength scale