Nanoparticle Surface Characterization
by X-Ray Photoelectron Spectroscopy
http://www.phi.com/Interface/PHI%20Interface%20Spring%2005.pdf
What is Nanotechnology?
Nano = 10-9
Nanoscale science: investigates the
properties of matter in the critcal range
of 1nm – 100 nm.
Nanotechnology: Is building and using
devices from 1 nm – 100 nm.
What Leads to Unsual Properties?
Any solid or liquid
has 2 components:
•surface
•bulk
The Macroscopic Case
One drop of
water:
100,000 bulk
molecules per
1 surface
molecule
Another Example...
•2 surface layers vs.
~10,000,000 internal
layers
•2 surface layers vs.
~5,000,000 internal
layers
•Percentage of surface:
0.000002% vs
0.000004%
Shrinking Down to the Nanoscale
C60
5%
10%
50%
100%
Properties of surface
atoms/molecules now
affect the overall
properties.
Properties Change According to Size!
Different sizes of gold particles = different optical
properties.
Nanoparticle Surfaces: What’s the Problem?
• Nano is all about surface!
• Surfaces are thin.
• Most surface coatings are
organic.
Boyen, H.-G.; Kastle, G.; Weigl, F. et al. Science 2002, 297, 1533-1536.
XPS: How Does it Work?
ejected
electron
X-Ray
KEelectron = hX-ray – BEelectron
http://www.almaden.ibm.com/st/scientific_services/materials_analysis/xps/
XPS Spectrometer: Basic Components
Settle, F., ed. Handbook of Instrumental Techniques for Analytical Chemistry. Prentice Hall. 1997.
1200
Counts / s
1000
800
600
400
200
0
300
295
290
285
280
C(1s) Binding Energy (eV)
Peak
Position
Area
% C1s
Carbon- ID
1
285.50
1457.1
52%
Pristine C60
2
287.45
489.75
18%
Mono-oxidized C
3
289.73
836.67
30%
Di-oxidized C
275