84
PROPERTIES OF INDIVIDUAL NANOPARTICLES
* *
Cui0
* *
* *
*
*
* * *
0 5
I
I
I
I
3
1
eV
.
Figure 4.11. UV photoelectron spectrum in the valence band region of copper nanoparlicles
having 20 and 40 atoms. [Adapted from C. L. Pettiete et al., J. Chem. Phys. 88, 5377 (1988).]
before the particles in the cluster beam enter the mass spectrometer, various gases
are introduced, as shown in the figure. Figure 4.13 shows the results of studies of the
reaction of oxygen with aluminum particles. The top figure is the mass spectrum of
the aluminum particles before the oxygen is introduced. The bottom figure shows
the spectrum after oxygen enters the chamber. The results show that two peaks have
c 2.9
2.7
% 2.5
$ 2.3
I I
I- 2.1
0
w
y 1.9
1.7
1.5
' 1 " " " 1 " " 1 " " 1 " " 1
5
10
15
20
25
30
NUMBER OF ATOMS
c 2 . 9 1
4
5
10
15
20
25
30
NUMBER OF ATOMS
Figure 4.12. Plot of measured electron affinity of copper versus size of nanoparticle. [Adapted
from C. L. Pettiete et al., J. Chem. Phys. 88, 5377 (1988).]