Nitrogen Atoms and Triplet States N2(B3Πg),
N2(C3Πu) in Nitrogen Afterglow
H. Coitout, G. Cernogora, L. Magne
To cite this version:
H. Coitout, G. Cernogora, L. Magne. Nitrogen Atoms and Triplet States N2(B3Πg), N2(C3Πu)
in Nitrogen Afterglow. Journal de Physique III, EDP Sciences, 1995, 5 (2), pp.203-217.
<10.1051/jp3:1995120>. <jpa-00249304>
HAL Id: jpa-00249304
https://hal.archives-ouvertes.fr/jpa-00249304
Submitted on 1 Jan 1995
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J.
Phvs.
5
France
III
(1995)
203-217
1995,
FEBRUARY
203
PAGE
Classification
Physics
Abstracts
52.80
52.20
Nitrogen
Nitrogen
Atoms
Coitout,
H.
Laboratoire
Physique
April
6
R4sum4.-
Cemogora
G.
de
(Received
est
ddduite
sitd
atomique
model,
density.
higher
N~(B~II~),N~(C~ f)
States
in
augmente
The
it is
shown
Atomic
5
x
due
that
density
I0~~cm~
et
8
des
partir
Plasmas,
des
July 1994,
d'un
avec
dues
to
the
is
durde
de
pour
)
of N~(B~
J7~
repopulation via
deduced
des
montrd
est
observ6e
est
la
par
que
le
from
density
the
fluorescence
observed
with
pulse
Frauce
temps
duration
in
state.
a
post-
une
pooling
caract£ristique
de
atomique. La densit6
densitds
sup6rieures h 5 x10~~ cm~ ~
de
l'impulsion.
and
increases
dons
reaction
d'azote
N~(C~ J7~ ) states is observed
pooling reaction of N~(A~ Z))
characteristic
decay time depends on
N~(C~ J7~
This
it
Orsay Cedex,
91405
1994)
October
repeuplement
un
densit6
la
l'intensitd
et
28
N~(C~J7~)
et
h
cin6tique,
modkle
observ6e
la
accepted
sont
Paris-Sud,
Uriiversit6
N~(B~J7~)
£tats
N~(C~ H~) ddpend
fluorescence
is
Magne
L.
fluorescences
fluorescence
la
fluorescence
than
A
l'dtat
de
de
Abstract.
This
revised
Ces
Z)).
N~(A~
d6croissance
de
Gaz
fluorescence
temporeIIe.
dtats
and
des
1993,
La
ddcharge
entre
Triplet
and
Afterglow
time
From
d'atomes
La
den-
afterglow.
a
kinetic
nitrogen
of N~(C~J7~) for
density
intensity.
dud
current
the
atomic
Introduction
1.
nitriding
metallic
for
surcathodes
[1].
using samples as
Nitride
efficiency
mixture.
layer production is a function of the
Process
ionic
bombardsurface
[2J. In
industrial
the sample heating is due to
temperature
reactor,
the
injected
in
The sample
electrical
temperature is then adjusted with the
ment.
reacpower
drives
metallic
sample and reactive nitrogen producthe heating of the
So, the discharge
tor.
and
damage on
tion.
Unfortunately,
with
d-cdischarges,
some
arcs
occur
some
can
cause
nitriding
in
studied
treated
order
eliminate
these
authors
have
surfaces.
In
to
arcs,
some
reactive
pulsed discharges [3J and in flowing afterglows [4]. In the flowing experiments, the
created
and
blown
the
excitation
species are
downstream
samples, out of the
upstream
on
So,
nitrogen
production
is
disconnected
from
the
heating
which
be
active
sample
zone.
can
extemal
controlled
by an
device.
In pulsed
discharges, sample heating and active nitrogen
production
discharge as in d-climits
done by the
conditions,
but, pulsed mode
arc
are
proLow
faces.
discharges are
mainly working
depends on the gas
nitrogen
pressure
The
reactors
are
duction.
Q
Les
Editions
de
Physique 1995
used
in
with
d-c-
industrial
discharges
reactors
JOURNAL
204
PHYSIQUE
DE
N°
III
2
flowing afterglow or pulsed discharges, the reactive gas is submitted during a short time
discharge. In flowing afterglow this time is a function of the gas flow and the discharge length. In pulsed discharge this time is the pulse duration.
order
understand
the discharge
evolution
and to
obtain
In
temporal
data for the optimito
of atomic
zation
nitrogen production, it is important to know the
characteristic
times to populate
and to
electronic
and
characteristic
times
nitrogen
relaxe
also
the
of
molecular
states
In
the
to
dissociation
direct
.
reassociation.
and
discharges,
electrical
In
potential
vibration
the
pumping
vibrational
last
of
The
characteristic
electronic
molecular
ground
higher
molecular
ground
leading
of
time
transfers
energy
molecular
of
level
inelastic
by
occurs
the
on
electron-vibration
and
dissociation
vibrational
state
[5, 61
processes
two
leading
levels
to
first
the
collisions
ground
to
by
levels
vibration-
pseudolevel
vibrational
a
above
state.
in
process
molecules
on
vibrational
state
order
the
on
about
:
I ps
P=
at
of
the
I
Ton
characteristic
for
a
time
equal to I eV. The
second
is
temporal
linked
evolutions
of the
to the
process
ground
Vibrational
distribution
distribution
and the
electron
function
state
energy
slow
(characteristic
time
longer than 1 ms) [6].
are
nitrogen density
Some
atomic
have
performed by NO
titration
been
measurements
by V-U-V- optical absorption
[8], mainly in flowing afterglows.
spectroscopy
measured
In this
presented
fluorescences
in a
N~(C~ H~) and N~(B~ H~)
paper
are
terglow. These
fluorescences
compared with the
calculated
deduced
from a
are
ones,
taking into
model
the coupling
between
account
N~(A~ Z(), N~(B~ H~) and N~(C~ H~
molecu-
energy
the
and
of
electron
mean
lar
states
a
;
curve
anharrnonic
.
impact
electronic
repulsive
nitrogen
molecular
which
[71
time
or
af-
kinetic
triplet
density.
atomic
Experiment
2.
experimental
The
pulsed
are
flow keeps
adjusted by
ent
is
gen
stream.
measured
by
to
order
discharge
then
the
gauges
two
pumped
is
:
with
down
high
a
10~
to
The
pulse
is adjusted by
duration
pulse duration
be fixed
from
can
The
rise
and
light
The
selection
channel
6 k
Data
In
the
molecules
scaler
~
slit,
a
in
cm
160
the
transferred
and
are
the
to
in
a
the
first
PC
the
5
by
high
a
voltage
tube
axis
detected
to
positive
U-V-
heated
is
hour
before
which
is
at
downgauge
200 °C an a
experiments,
the
repetition
rate
also
from
used
10
through a MgF~ window.
(HRS2
Jobin
Tvon).
side-on
photomultiplier
a
930
with
range.
nm
The
System
Research
counting.
photons
photomultiplier
5R440)
The
photons
100
to
Hz.
Wavelength
Behind
the
(R943-02
signal
output
connected
trigger.
as
Hz
to
counting
a
is
is
multi-
done
wide.
computer
near
one
generator
I ps.
capacitance
a
tube
monochromator
resolved
ns
ms
the
pump.
and
about
(Standford
160
each
are
is
nm
pulse
to
focal
light
the
fast
channels
visible
[91
64
25 ps
diffusion
a
master
a
during
flow
gas
by
ton
pulse
along
the
preamplifier
(5R430) for time
(6144)
are
by
sensitive
a
of
observed
out
exit
Hamamatsu),
amplified with
over
is
carried
monochromator
time
fall
emitted
is
produced
is
and
upstream
gauge
cleanliness
and purity,
The
time
discharge
The
I.
pirani
a
nitrogen
improve
maintained
is
tube
Figure
in
shown
tube of 50 cm length and 1.5 cm
intemal
diameter.
nitroA weak
pyrex
a
the gas in high purity
condition
without
gradient.
Flowing
conditions
pressure
needle
valve
and a
throttle
valve
downstream.
The
gradiupstream
a
pressure
In
d-c-
is
device
in
generator,
to
range
system
be
the
analyzed.
more
intense
observed
bands
of
the
neutral
N°
NITROGEN
2
ATOMS
AND
STATES
TRIPLET
205
t2
P-u
N-v
~ v
c-c
P-c
~i
++~
~
I
I
j
Hv-p-c
'
I
i
JOURNAL
206
N+N+N~
coefficient
The
for
this
effect
range
order to
minimize
pressure
In
tow.
level
of
lower
than
v'= 11
in
occur
of
Because
level
but
of
cm~ s~
[101.
important
be
can
for
give
can
In
fluorescence
We
the
of
our
a
few
than
vibra-
lower
vibrational
this
that
part
higher
the
on
suppose
can
lower
the
pressures
observe
we
recombination,
the
transfers.
vibration-vibration
wavelength
the
N~(B~ H~)
of
~~
2.4x10~
=
effect
levels
does
not
afterglow.
early
the
~
reassociation
Atomic
after
N~(B~IT~,v'=11)+N~.
~
contribution
the
N~(B~ H~ ).
tional
2
N°
III
Lj_~
is k~
process
is negligible,
this
PHYSIQUE
DE
v'= 2.
is
of
range
The
optical
our
intense
more
device,
transition
is
the
vibrational
observable
lower
:
N~(B~IT~,v'=2)~N~(A~J7),v"=0)+hv
which
is
emitted
at
Experimental
3.
Figure 2a
d=700ps.
Following
sion
for
=
775.4
nm.
Results
the
presents
In
I
the
this
fast
higher
N~(C~H~)
post-discharge,
decay, a weak
P=0.9
pressure
a
emission
fast
for
decay
fluorescence
and
Ton
can
be
due
seen.
pulse
shorter
a
and
P=0.2Ton
mainly
to
Figure
2b
pulse
long
a
radiative
losses
duration
observed.
N~( C~ H~ )
shows
d=50ps.
duration
is
In
these
emis-
condi-
fluorescence
becomes
important.
the
more
Figures 3a and 3b present typical
fluorescence
semilogarithmic
normalized
in
N~(C~ n~)
plots. In the former, we see that the
fluorescence
characteristic
time
shorter
the
becomes
as
pulse duration d increases.
The
later
the
shows
that the
fluorescence
shorter
becomes
one
as
discharge
figures, it can be seen that the
increases.
In both
fluorescence
be
current
can
correctly
described
by a monoexponential decay. So, we use a non linear regression in order to
fit
experimental
fluorescences
by a function on the form :
tions,
I
~s
I
fi
d
°
t
~
~
~
fl
fi
g
w
fi
~
200
o
MO
600
Time
Fig.
of
2.
a)
Typical
N~( C~ J7~, v'=
4
)
800
loco
1200
o
20
4O
60
(ps)
record
emission.
N~(C~J7~,v'=4)
for
P
=
0.9 Ton,
d
=
emission.
50 vs.
P=0.2
Ton,
loo
80
Time
120
14O
160
(ps)
d=700
vs.
b) Typical
record
N°
NITROGEN
2
ATOMS
TRIPLET
AND
STATES
207
SO Pa
loo
pa
=
200
Pa
z
u
w
I
8
g
fi
u
g
~
soo
pa
30
mA
~
~
~
z
i
o
ms
~
~o.1
s
~o
loo
fl
ma
mA
~
3oO
~
soo
~~~
200
loo
o
Fig.
P
=
0.2
Tow,
charge
1=
b)
100 mA.
values.
current
P
SOD
o
N~(C~ J7~,
=
0.9 Ton,
v'= 4
d
influence
in
pulse
of
Figures
duration
and
4a
300
=
and
)
for
fluorescence
soo
MO
several
700
600
Boo
(ps)
pulse
fluorescence
duration
for
values.
several
dis,
50 vs.
=
shown
200
N~( C~ J7~, v'= 4
post-discharge
Nonnalized
jN~(C~1I~jjit)
The
loo
Time
post-discharge
Normalized
a)
3.
MO
30O
(ps)
Time
discharge
Cexp(current
on
vi).
the
N~(C~ H~ ) decay
frequency
v
is
4b.
measured
normalized
comparison
between
N~(B~H~) and N~(C~H~)
fast
conditions.
Emission
from N~(B~ H~) presents
experimental
a
characteristic
decay times of
decay in the early afterglow. It is important to notice that the
observed
by de
This
been
the
last point has
value in the far afterglow.
both
reach
states
same
They analyzed
the
mixture
[IIIin
pulsed
discharge in He,N~
Benedictis
R-Fal.
et
has
the
exponential
decays.
The
slowest
of
three
fluorescence
the
N~(B" H~
same
one
as
sum
characteristic
decay time as N~(C~ H~).
Figure
5
fluorescences
4.
shows
in
the
a
same
Modeling
this
from
emission
lifetime
is equal to 37 ns [91. Consequently,
state
N~(C~ H~) radiative
an
gain
explained
by
only
be
during the post discharge can
processes.
ground
molecular
from
collisions
electronic
of N~(C~ H~ ) and N~(B~ H~ by
The
excitation
the
afterglow,
the
and
7.4
eV.
In
equal
11.I
eV
respectively
require
electron
to
state
energy
that
work,
decrease
[121.
In
this
of
electrons
density and the mean
electron
assume
we
energy
populated
is no
distribution
function
electrons
in the
afterglow, the tail of the
more
energy
species
life
triplet
Some
long
significant
excitation
of
obtain
enough in order to
states.
are
a
vibrational
levels
species
mainly
the
afterglow.
These
in
the
present
are
molecular
atomic
ground state N(~S ) and
molecular
ground state,
metaN~(X~ Z), w) of the
Z(,
Z().
directly
repopulate
w)
molecules
that
stable
We
N~(X~
cannot
N~(A~
state
suppose
[131.
N~(B~ H~) and N~(C~ H~) states but can play an important role in a stepwise
process
Z(
), the only radiative
transitions
Kaplan bands [91. These
the Vegard
Conceming N~(A~
are
with
forbidden
losses
be neglected in comparison
transitions
and
then the
radiative
can
are
JOURNAL
208
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3
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.
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III
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2
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ru
Z
0
200
0
4o0
Discharge
Fig.
veral
the
b)
1=300mA.
pulse
other
duration
loss
values.
v'= 4
P=0.5
main
loss
The
Effective
about
Tow.
Because
pressure
N~(B~ H~)
one
and
frequency
600
in mA
pulse
versus
frequency
duration
for
discharge
versus
severaI
pressure
for
current
se-
Ton.
atoms.
for
) decay
N~(C~J7~,v'=4) decay
processes.
and
of
N~(C'J7~,
Experimental
quenching by
[lsl
source
Experimental
al
4.
values.
Current
for
processes
lifetime
of
its
N~(C~ H~) production
of
this
N~(A~
state
long
lifetime,
via
pooling
Z()
is
are
N~(A~
Z()
reactions.
diffusion
the
typically
of
is
some
probably
to
the
wall
milliseconds
the
main
N°
2
NITROGEN
ATOMS
TRIPLET
AND
STATES
209
Calculation
w
I
~
#
~
~
N~(C)
~
msasunsmBnt
o-I
~o
_~
N~(8)
measurement
15
E
~
o.01
o
200
100
Time
Fig.
Experimental
5.
1=100mA
and
this
calculation
In
d=
the
.
N~( B~ H~ )
N~( A~ Z( )
and
R7
reaction
According to these
N~(A~ Z) ), N~(X~ Z))
.
fluorescences
Comparison
50 vs.
remarks,
N~( C~ H~ )
pooling
and
we
assume
that
transfers
radiative
A~ J7)
N~( C~ lT~ )
~
N~ ( B~ J7~ )
N~( A~ Z) )
~~~ ~~ ~~~
~
~~~ ~~
hv
RI
+
hv
R2
~~~Lf~ ~2~ ~~ ~
Z) )
R3
X~ 27( )
R4
+
N~( X~
~
%~2(
lo
)
atoms
Z) )
+
N( ~S )
N~( X,w
~
kA
N~( B~
+
N~( C~ J7~ )
~
J~ ) quenching by
<
+
N
R5
N
molecules
N~( B~ J7~ )
+
N~
~
products
R6
"Q
.
collisional
transfer
N~(A~ Z)
.
N~(A~
+
:
N~( X~
Z() diflfizsion
Z(,
w
>
6
)
ki
N~( B~
~
the
wall
)
J7
~
x
to
:
frequency v~
P
=
0.9
Ton,
conditions.
N~(B~
with
:
+
N~( A~
coupled
:
N~
~2(A ~ Zu ) quenching by
is
state
reactions
~
~
.
N~(C~H~)
N~( B~ lT~ )
reactions
for
[NJ "2.8x10~~cm~~
following
the
N~( B' J7~, v'= 2 ) for
corresponding
initial
dud
fluorescences
neglected
Z) )
N~( A~
*
calculated
is
N(~S ) by
and
N~( C~ J7~, v'= 4 )
of
with
MO
300
(ps)
R8
+
N~( X' Z~,
~
w
6
)
R7
l§),
JOURNAL
210
If
Bessel
a
diffusion
coefficient
diffusion
The
D~
[151
The
9
used
previously,
seen
loss
is
radiative
all
the
collisional
all
the
electronic
R2,
and
Rl
Rate
coefficients
we
relevant
are
considered
z~
I.
used
the
=
=
in
presented
are
without
of
then
N~(C~ H~)
that
lifetimes
I-e-
Tow
300
at
afterglow
the
for
N~( C~ lT~,
v'=
0
)
8.9
ns
for
N~( B~ lT~,
v'=
0
)
ofN~(A~Z) ), N~(B~ J7~)
coefficient
Rate
=
k~~
x
lo-to
7 7
X
10'~~ Cm~ g~
~A~
k~
~
2
k~~
~
x
~ ~
3
~~~~ ~~~
~
~
lU'~2 cm3 ~.,
10'~° cm~ s'~
R7
the
K
and
P
(Ton)
~
coeffi-
vibrational
is
As
observed.
level
v
of
these
states.
So,
and
N~(C~ J7~ )
states.
.1
j~~j
[23]
[24]
j25j
[26]
1.74x10~
~~
These
I.
discrimination.
Reference
j 5
R4
Table
[91
ns
kinetics
in
the
37
the
in
fluorescence
fluorescence
the
radiative
kf~
R8
is
radius.
of I
vibrational
suppose
describe
~~
R6
D~
where
tube
the
pressure
a
N~(C~ H~ )
for
process
reactions
can
to
Reaction
R5
for
D~ /A~
=
if R is
R/2A
to
measured
states
dependence
vibrational
have
is v~
R2.
for
z~
Table
emission
for
N~(C~ H~)
we
length equal
N~(A~ Z() has been
(for v
0).
the only
production
2
N°
=
R3
no
processes
and
of
III
frequency
diffusion
the
diffusion
the
cm~ s~
only by
been
radiative
radiative
+
coefficients
have
N~(B~ H~)
A
and
reaction
lost
rate
cients
the
=
is
state
have
155
assumed,
is
coefficient
pooling
The
this
profile
radial
PHYSIQUE
DE
~
jls]
we
For
0
for
for
the
=
N°
2
In
the
NITROGEN
model,
kinetic
these
ATOMS
processes
AND
TRIPLET
by the
described
are
A~=~
population
the
vibrational
the
radiative
into
The
N~(B~H~,
distribution
of
transition
A~
=
A~
=
1.39
x
6.25
x
evolution
time
=0)
v
the
between
lo?
levels
v'=
0
10~ s~
for
N~( B~ lT~,
v'=
of
triplet
three
the
radiative
is
which
the
are
depends
cascade
Therefore,
known.
not
v
levels
0
=
on
only
is
taken
[91
N~( C~ lT~,
densities
by
which
for
~
N~( B~ lT~,
0
~
N~( A~
states
is
)
Z(,
v"=
v"
=
)
0
)
by
described
then
0
the
following
:
iN2iBii
kl
x
~i~(~ii
kj
=
~
equations
These
densities.
also
The
During
milliseconds.
iN21A jiivD
A
lN~( All lN~(
x,
w
6
a
jN~(Aji~ +A~jN~icjj
+
+
+
kA
iNi i
N
II
kj
jN~iAjjjN~iX,w.
~
*
611
k~jN2 (Xii1
=kj_~jN2(Aii~-AiiN2(Cii.
~~~()~~
[NJ l171
iN2iAii~
kA
iN21B11(A4
[NJ
are
v
state
populated
more
=0)
s~
of
~~~(~~~~ "A2
and
electronic
upper
the
probabilities
transition
~4
N~(A~Z(,
and
probabilities
transition
The
account.
equations
of
211
A~=~
and
~l
The
STATES
depend
temporal
the
observed
on
the
temporal
evolutions
of
fluorescence,
evolution
species
these
we
can
of
are
[N~(X~Z), v'=6)J
slow,
suppose
on
that
[16J
and
of
a
few
[N~(X~Z),v'a
6)J
the
order
constant.
are
density at the beginning of the afterglow presented in Table II have been
discharges for N~(A~Z() [181, N~(B~H~) [191 and N~(C~H~) [201. The
results
of a
numerical
simulation
[21].
from
the
N~(X~ Z), v'a 6 ) density is taken
Figure 6 shows
calculated
N~(A~ Z)), N~(B~ H~ ) and N~(C~ H~ ) densities in the afterglow
decays for the three
for [NJ =3 x ld~cm~~
and
obtain
monoexponential
P=0.9
Ton.
We
B~
)
characteristic
times
which is the
The
and
)
decay
the
N~(C~
states.
N~(
H~
not
are
same,
H~
Z))
)
experimental
5).
the
observations
and
(Fig.
N~(A~
N~(B~ H~
present the
contrary to
same
these
reaction
R7.
decay. This is due to the strong coupling
between
via the
two
states
N~(X' Z(, v'a 6) density could be
reaction
overestimated
and so, N~(B~H~) gain due to
obtain
overestimated
kinetic
scheme,
R7
be
If
reaction
R7
in
could
neglect
too.
our
we
we
normalized
(calculations)
shown
in Figure 5. A
the N~(B~ H~) and N~(C~H~)
fluorescences
obtained.
The
calcuwith
experimental
fluorescences
in the far afterglow is
good
agreement
good
)
slopes.
fastest
in
The
is
lated
decay of N~(B~ H~
not
agreement
state
presents
two
one
with the
is slower.
modelling, the fast decay is only due to radiative
experiment
which
In our
kinetics.
could be a missing fast gain
for N~(B~ H~) in our
Anyway,
loss.
So
there
process
this
calculated
measured
fluorescences
for
disagreement stops in the far afterglow where
and
experimental
fluoparallel.
obtain
of
the
becomes
Consequently,
good
fit
two
states
as
we
a
reaction
in the
far
afterglow
neglecting
R7, we will not
consider
this
rescences
any
more
The
values
determined
process
in
of
in
our
d-c-
kinetics.
212
JOURNAL
Table
densi~y
Initial
II.
beginning of
the
at
PHYSIQUE
DE
the
N°
density (cm'~)
lN~(A)lo
lN~jB)j~
jN~jc)lo
lN~jx)j
jN~jx,wm6)j
0.09
6 10~~
6 10~°
6 lU~
3,2 10"
1,2 10~~
0,2
910~~
8 10~°
5 10~
7,1
10"
2.810~~
0,5
1.5 10~~
10~~
410~
1.7 10~~
6,8 10~~
0,9
1,2 10~~
1,1 10~~
2 10~
3,2 10~~
1,410'~
3,85
5 10~~
2 10~~
10~
IA 10~~
lo
2
afterglow.
Initial
Pressure
III
5.6
10~~
~~
N~(A)
/
io"
I'
m
E
lo
~
"
.~
(B)
N
2~
_-~~
2
m
I
lo
~
(c)
N
~~
ios
~
~~
~
~
~
3
10O
300
200
400
Time in Vs
Fig.
Calculated
6.
atomic
input
as
=
3
x
of
N~(C~J7~), N~(B~J7~)
and
N~
(A~Z))
for
P=0.9
Ton
assuming
an
10~~ cm~
N~(C~H~)
Calculated
density
densities
NJ
density
fluorescences
N~(C~H~)
parameter.
are
shown
fluorescence
in
Figure
becomes
7
for
shorter
P=0.9
Ton
as
atomic
with
atomic
density
in-
quenching of N~(A~Z() by atoTnic
nitrogen
(reaction
R5).
reduce N~( C~ H~ ) gain by pooling
N~( A~ Z( ) losses
reaction
R3.
In Figure 8 the
atomic
nitrogen density (used as input data) is shown as a function of the
calculated
N~(C~ H~) decay frequency. For low atonfic density, the dependence of calculated
N~(C~ H~) decay frequency on atoJnic density
becomes
When
weak.
atomic
the
density decreases.
This
is
due
to
the
N°
NITROGEN
2
N~(A~
creases,
then
in
the
from
the
of
that
effect
this
of the
increases
model
the
estimations
to
Figures
~~,2
density
213
the
loss
by
low.
becomes
diffusion
We
shown
and
9a
estimate
can
we
9b.
in
In
atomic
Figures 4a
Figure 9a,
nitrogen
and
it
can
4b.
be
~
10"cm~
(Nl.310"cm~
cm~
iNisl©
8
#
o lo
U-
7J
_~
l%
E
iNi
s
"
lo
cm
$
Z
[Mt.
i
lo,4~~
~
jN1310"cm~
[N[-210"cm~
/
O 01
200
loo
0
Time
Fig.
7.
N~(C~J7~)
Calculated
fluorescence
for
in
several
400
300
ps
atomic
density
values,
~~~~
P=3 85 Tom
~
4
c
m
m
I
$~
~
l
'
P=0.9
lE+11
lE+3
Fig.
requency
for
pressure
values.
Decay
(C)
N
8,
-
Calculation
can
and
see
decreases.
pressure
Figure 8
frequencies
in
shown
are
towards
atomic
in
shown
N~(C~ H~) decay
experimental
decreases
fluorescence
as
STATES
TRIPLET
quenching
atoTnic
N~(C~ H~)
of
results
these
by
lossed
sensitiveness
Figure 8
Using the
sults
Z()
AND
ATOMS
esults.
Atomic
nitrogen
Frequency
density
P=
0.9 Ton.
density
Some
seen
re-
that
atomic
density
ciation
is
atomic
density
not
pulse
with
increases
reached
in
the
increases
duration.
It
the
III
that
seems
pulse durations
discharge
current
of
case
with
PHYSIQUE
DE
JOURNAL
214
steady
a
shorter
for
than
pulse
any
2
N°
state
for
disso-
molecular
700 ps. Figure 9b
duration
value.
shows
that
o
o
~
°
i
~m
.
.,m
fl
E
"
~
.
fl
~'
~
~
m
lE+14
~E
*
m
i=300rrub
~
5~
°
PC305TO«
*
P=09Tarr
05Tarr
lE+13
loo
lo
Discharge
1000
Duration
in ps
lE+15
l'
/
ro
,,'
E
/
w
W
Ul
W
/
/
,
~~
/~
u
/
c
j~
fig
I
~'
$
P
'
'
~
/
'
~
A
~schwge
= 50
Dischwge dUmlan
100 ps
dursban
~
*
ps
=
~schwge
E+12
0
in
Current
Fig.
~(C'J7~
)
reported
from
he
experimental
values
in
Figure
of
~(C'H~
4a.
)
decay
equency
9.
-
b)
Atornic
reported
in
mA
a)
density
stimations
Figure
versus
4b.
discharge
current
2
N°
NITROGEN
In
experimental
our
5
x10~~cm~
5.
Discussion
The
of
results
several
technic
compared
be
can
STATES
density
215
2x10~~cm~
from
ranges
nitrogen
discharges
atomic
with
DC
of
microwave
or
optical
VUV
spectroscopy,
mass
:
to
absorption
[281,
in
measurements
titration
NO
post
using
studied
were
emission
and
system.
used
was
dissociative
ionic
nitrogen
atomic
the
afterglows
flowing
positive
absorption
VUV
by
calculations
our
Mainly,
first
the
conditions,
TRIPLET
AND
~
discharges.
of
ATOMS
low
in
afterglow
pressure
[281.
recombination
nitrogen
where
conditions,
these
In
atoms
[N] was
about
instance, in
For
produced
were
10~~ cm~
~
discharges
workplasma, far enough from the discharge in
the NO
chemiluminescence
without
perturbation
from the light
emitted
by
order
titration
millisecond
the
excitation
Thus, NO
gives [N]
only at about one
tone.
measurements
after
the
discharge. In DC discharge flowing afterglows, for I= loo mA, the UQl density inwith
increasing
from
0.6 to 2 Tow [291. In
from 2 x10~~ cm~ ~ to 10~~ cm~ ~
creases
pressure
afterglow at 8 Tow, by NO
titration
microwaves
the nitrogen
density is about ld~ cm~ ~ [301.
Yamashita
used by
[171 in nitrogen discharge and post discharge.
Mass
spectroscopy
was
titration,
deduced
density is of 4x
After
calibration
with
the
nitrogen
absolute
NO
an
10~~cm~ ~ in a 4 Tow
in
discharge and
microwave
is
usable
discharge.
Mass
spectroscopy
nitrogen
The
ing in
atoms
gas flow,
observe
to
can
NO
a
discharge
without
nitrogen flowing
post
In
measured
be
injected
is
any
with
limitation,
time
afterglow,
atomic
but
the
to
mainly
emission
the
from
afterglow,
nitrogen
atomic
at
method
The
Some
possible
effective
have
other
electronic
influence
lifetime
any
v'=10,
after
the
accordance
in
metastable
is
shorter
influence
on
system
in
and
12
11
positive
afterglow.
first
for
exist
in
of
develop.
to
easy
the
[321.
Ton
beginning
the
we
lifetime
post
must
is
is
observed
the
[NJ
measure-
discharge,
gives
discuss
their
now
54ps.
its
Moreover
does
state
during
nitro-
gives
pooling
system
for
used
(LRA)
pure
of
Because
[141. So this
process
which
fluorescence
of
So
radiative
positive
be
cannot
[311. In
state
first
the
aftergtlow.
the
quenching
of the
N~(C~ H~)
N~(B~ H~)
of
Afterglow
Rayleigh
Lewis
P=2
kinetics.
presented
singlet state N~(a~ H~)
because
not
emission
system
useable
at
paper,
technic.
with
other
could
the
emission
ld~cm~~
about
is
~N~+N~
calibration,
NO
states
the
on
molecular
The
levels
beginning of the
presented in this
densities
atomic
not
the
positive
of
above,
mentioned
reaction
ments
densities
first
the
vibrational
the
microwave
gen
of
technic
this
recombination
N+N+N~
leads
titration.
NO
of
downstream
a
few
not
have
hundred
microseconds.
N~(E"Z~) could lead to the
[27J. The ~nly N~(E~ Z~) gain
recombination
atomic
of
creation
process
that
N~(C~H~)
via
maintain
could
radiative
this
and
density
collisional
during
the
transfers
afterglow
is
:~
N( ~S )
+
N( ~D )
+
N~
Ll
N~( E~
~
Z( )
+
N~
N
In
lifetime
overestimate
N~(E~ Z() effective
we
afterglow and we only consider loss
processes
N~(E~ Z)) density is the solution of the equation
order
to
in
the
stant
Then
assume
which
that
lead
N(~D) density
to N~(C~ H~)
is
con-
creation.
JOURNAL
216
PHYSIQUE
DE
ajN~(Eij
v~ is
where
the
of
sum
frequency, G~
transfer
the
Einstein
the
creation
is
Z()
N~(E~
Then
density
by
+
N°
coefficient
and
[271
al.
et
[N2(E )lO
"
J840s~~
the
measured
have
N~(C~H~).
to
collisional
the
iN(~siiiN(~DiiiN~ik[-~.
G~=
G~
exp(- vE t)
G~)
$
~
+
E
E
Bums
of
recombination
atomic
is
[N2(E)I (t)
N~(E~Z()
2
G~
emission
spontaneous
rate
iN~i
v~=A~~~+k~~~
iN~( El i
v~
=
at
III
radiative
Einstein
The
cascade
and
the
collisional
emission
spontaneous
k~_~
from
transfer
A~_~
coefficient
equal
is
equal
to
density can be
[N~(E)J(t)~JG~/v~ after
approximated
initial
density [N~(E)J~
assume
as
an
10~~cm~~
than
So
N~(C~H~)
form
lower
add
gain
in
the
must
constant
we
a
"10~~cm~
~
II
[N~(E
[N(S
II
strongly
°'G~.
We
overestimate
this
gain
assuming
that
can
v~
cm~~
=10~~
[N(D)J
and
metastable
atoTnic
density
(which
the
maximum
is
value
an
meato
5
x
10~
sured
10~
~~
in
pooling
is
=
Ton,
Then,
2
and
find
G~
x10~~cm~
~
coefficient
transfer
of
because
[331)
we
N~(C~ f )
the
on
I
discharge
[101.
reaction
influence
P
For
D-C-
a
cm~ s~
collisional
the
and
cm~ s~
~~
7.7
it
x
10~ cm~
is
is
estimated
efficiency, N~( E~
recombination
a
=
So
5~
quenching
20ps, if we
~
coefficient
s~
reasonable
while
to
the
assume
Z(
k$
~
initial
that
~J
k$
gain
N~(E~
~
=
2.4
from
Z()
x
the
has
no
fluorescence.
Conclusion
The
of N~( C~ H~ ) is coupled
with
metastable
N~(A~ Z() and nitrogen atom
experimental
C~
The
decay time of N~(
different
values
H~ ) can be fined trying
density in the kinetic
model.
This
give a good
atom
method
could
estimation
discharges.
density in electrical
atom
fluorescence
centrations.
nitrogen
nitrogen
con-
of
of
References
[II
[2]
[3]
[4]
[5]
M., J. Appl. Phys. 44 (1973) 1489, Study of ion-nitriding.
H. A. et al., Binary Alloy phase Diagrams,
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Henrion
G., Fabry M., Hugon R., Bougdira J., Spectroscopic
investigation of a
Hudis
Wriedt
temporal postdischarge plasma for ion nitriding, Plasma
Sources
Sci.
Technol.
1 (1992)
II?Ricard
A., Oseguera J. E., Falk L., Michel H., Gautois M., Active
Species in
Microwave
Postdischarge For
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Plasma
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Capitelli M.,
Dilonardo
M.,
Non-equilibrium
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[6]
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17]
Henon
(1990)
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Feneira
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a
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:
in
ni-
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J. L.,
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Kinetics
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J.
N°
[9]
NITROGEN
2
Krupenie
A.,
Lofthus
H.,
P
ATOMS
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AND
TRIPLET
of
molecular
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discharge
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STATES
nitrogen,
217
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J.
Ret
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6
(1977)
57
(1985)
Data
113.
[10]
H.,
Brunet
J.,
Serra
Rocca
Model
for
a
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in
Appl. Phys.
J.
1574.
[I ii
de
S.,
Benedictis
regime
[12]
Gorbunov
N.
A.,
in
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G.,
Dilecce
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of
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Decay of excited
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pulsed
RF
Kolokolov
plasma
N.
of
a
[13]
(1991) 6.
C., Capitelli M., Coupled
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[14]
Magne
[15]
Zipf
E.
Jr,
C.
Diffusion
Phys. 38
Chem.
[16]
Capitelli
M.,
[17]
Yamashita
[18]
Cemogora
T.,
Ferreira
[21]
Touzeau
nitrogen
glow
M.,
J.,
Loureiro
Piper
Ferreira
G.,
L.
State
Piper
State
to
[24]
Piper
G.,
L.
Heidner
induced
[26]
Piper
G.,
L.
state
Bums
Queffelec
N(
Golden
J. L.,
as
N.,
S.
At.
:
Z/
J.
state,
electronic
of
70
and
populations
(1984)
Phys. 17
populations
(1984)
afterglow,
vi~
(1983)
L251-256.
(1979) 4248.
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