Chemistry Reference
In-Depth Information
It finally leads to the production of the required negative chlorine ion and
hydrogen.
The ion-ion recombination reaction induced by Ne
Xe
+
+
Cl
−
+
XeCl
∗
(
Ne
→
B;
v
0
)
+
Ne
(8.39)
XeCl
∗
(
→
C;
v
0
)
+
Ne
(8.40)
results in the formation of the vibrationally excited B and C states of the XeCl
molecule, where XeCl
∗
(
B;
v
0
)
is predominantly produced. The collision reaction
between Xe
∗
and HCl (
v
0) is thermoneutral, i.e., its branching ratio is almost zero
with respect to the formation of XeCl
∗
. Thus, the upper laser level is mainly formed
via reaction (8.39), while the harpooning reaction
=
Xe
∗
XeCl
∗
+
HCl
(
v
>
0
)
→
(
B, C;
v
0
)
+
H
(8.41)
plays a minor role only. The vibrational relaxation
XeCl
∗
(
)
+
→
XeCl
∗
(
=
)
+
B;
v
0
Ne
B;
v
0
Ne
(8.42)
results mostly from collisions with the buffer gas neon and the unstable XeCl
∗
(
B;
v
molecule decomposes within 11 ns by emission of photons with a max-
imum intensity at the wavelength 308 nm [73]. All vibrational levels XeCl
∗
(
=
0
)
B;
v
)
and XeCl
∗
(
C;
v
)
are not only subject to vibrational relaxation but also to exchange
reactions
XeCl
∗
(
XeCl
∗
(
B;
v
)
+
M
C;
v
)
+
M
(8.43)
by collisions with M
=
Ne, Xe, HCl, Cl, e
−
as well as quenching in two-body
reactions
XeCl
∗
(
B, C;
v
)
+
M
→
Xe
+
Cl
+
M
(8.44)
and three-body collision processes
XeCl
∗
(
Xe
2
Cl
∗
+
B, C;
v
)
+
Xe
+
Ne
→
Ne
(8.45)
leading to the generation of Xe
2
Cl
∗
. Further details of the vibrational and quenching
kinetics of XeCl are given in [74].
8.2 PLASMA SURFACE CHEMISTRY
Low-temperature, nonthermal plasmas are effective tools for surface treatment of
materials in a broad field of applications. The use of plasmas offers the possibilities
of selective control of various parameters and as dry processes with low mate-
rial and energy insert they are environmentally friendly. Plasma surface chemistry
