Chemistry Reference
In-Depth Information
CH
4
H
2
+e
−
+e
−
CH
3
CH
2
CH
2H
+H
+(H,H
2
) +(H,H
2
)
CH
4
C
2
H
6
+H(−H
2
)
+H(−H
2
)
+H+M
+H+M
C
2
H
5
CH
3
+H(−H
2
)
+H+M
C
2
H
4
+H(−H
2
)
+H(−H
2
)
+H+M
CH
2
C
2
H
3
+H(−H
2
)
+H+M
+H(−H
2
)
C
2
H
2
+H(−H
2
)
CH
C
2
H
+H(−H
2
)
+H(−H
2
)
C
2
C
FIGURE 2.2
Reaction schemes for the electron collision of CH
4
induced CH
3
,CH
4
,and
CH formation. (According to Röpcke, J. et al.,
J. Phys. D: Appl. Phys.
, 34, 2336, 2001.) H
2
dissociation and of the transformation of C
1
H
x
and C
2
H
y
species by reactions with H atoms in
diamond plasma CVD. (According to Ma, J. et al., Exploration of the gas phase chemistry in
microwave activated diamond depositing plasmas by laser spectroscopy, in
ISPC 2007 Peking
CD
, ISPC, Peaking University, Beijing, China, 2007.)
M
indicates the action of the wall.
and oxygenated hydrocarbons. A carbon chain growth is supposed to occur mainly
by the reaction
C
n
H
2
n
+
2
+
CH
4
→
C
n
+
1
H
2
n
+
4
+
H
2
.
(2.6)
According to the practical application an essential problem is the bad selectivity
of the plasma process [22,23]. Products of the methane conversion include syngas,
gaseous products as ethylene, acetylene, and propylene, liquid hydrocarbons, plasma
polymers, and oxygenates. The complexity of hydrocarbon plasmas is demonstrated
in [24] by review of plasma chemical reactions in low-pressure acetylene plasmas.
A spectacular example of application of nonequilibrium plasma chemistry is the
deposition of diamond films.
