58 4 Gas-Phase Synthesis of Nanoparticles
Figure 4.15 displays the energy transferred to the particles by the electrical field
again; however, on a logarithmic scale for the collision frequency. The three ranges
with the different signs of the electrical of the particle charges are indicated.
The design of a microwave plasma system for nanoparticle synthesis, working
in the low-pressure regime, is displayed in Figure 4.16.
Figure 4.15 Energy transferred in an
oscillating electric field to charged particles
as a function of the collision frequency,
which may be seen to be equivalent to the
gas pressure. In this graph, the ranges with
different particle charges are indicated. It is
important to note that in physical reality
these ranges are not clearly limited; in fact,
to some extent, they are overlapping.
1
10
100
1000
10000
log(collision frequency)
0
0.01
0.02
0.03
0.04
0.05
transferred
energy
posiƟve
posiƟve and negaƟve
negaƟve
Electrical charges of the parƟcles:
Figure 4.16 Design of a microwave system
working in a pressure range that ensures
positively charged particles. A carrier gas also
containing the reaction gas transports an
evaporated precursor into the plasma zone.
The reaction product, nanoparticles, is
collected after the reaction zone. Microwaves
are coupled into the device with the
waveguide.
Waveguide
Resonant
microwave cavity
Cut-off tube
Product
and off-gas
Microwave
plasma
ReacƟon
tube
Carrier gas and
evaporated precursor
Figure 4.15 displays the energy transferred to the particles by the electrical field
again; however, on a logarithmic scale for the collision frequency. The three ranges
with the different signs of the electrical of the particle charges are indicated.
The design of a microwave plasma system for nanoparticle synthesis, working
in the low-pressure regime, is displayed in Figure 4.16.
Figure 4.15 Energy transferred in an
oscillating electric field to charged particles
as a function of the collision frequency,
which may be seen to be equivalent to the
gas pressure. In this graph, the ranges with
different particle charges are indicated. It is
important to note that in physical reality
these ranges are not clearly limited; in fact,
to some extent, they are overlapping.
1
10
100
1000
10000
log(collision frequency)
0
0.01
0.02
0.03
0.04
0.05
transferred
energy
posiƟve
posiƟve and negaƟve
negaƟve
Electrical charges of the parƟcles:
Figure 4.16 Design of a microwave system
working in a pressure range that ensures
positively charged particles. A carrier gas also
containing the reaction gas transports an
evaporated precursor into the plasma zone.
The reaction product, nanoparticles, is
collected after the reaction zone. Microwaves
are coupled into the device with the
waveguide.
Waveguide
Resonant
microwave cavity
Cut-off tube
Product
and off-gas
Microwave
plasma
ReacƟon
tube
Carrier gas and
evaporated precursor