Use of the linear absorption coefficient for absolute comparison of plasma films in the mid-IR range
In this work, we present the mid-infrared analysis of analogues of Titan's aerosols produced in a radio frequency capacitively coupled plasma (RF-CCP). The influence of the gas mixture on aerosols spectra is also studied through the analysis of the carbonaceous bands of the spectra, and its Gau...
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| Zitieren: | Use of the linear absorption coefficient for absolute comparison of plasma films in the mid-IR range / T. Gautier, N. Carrasco, A. Mahjoub, I. Stefanovic, C. Szopa, G. Cernogora, E. Hadamcik, J. Winter // Вопросы атомной науки и техники. — 2013. — № 1. — С. 168-170. — Бібліогр.: 12 назв. — англ. |
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irk-123456789-1092612016-11-23T03:02:21Z Use of the linear absorption coefficient for absolute comparison of plasma films in the mid-IR range Gautier, T. Carrasco, N. Mahjoub, A. Stefanovic, I. Szopa, C. Cernogora, G. Hadamcik, E. Winter, J. Низкотемпературная плазма и плазменные технологии In this work, we present the mid-infrared analysis of analogues of Titan's aerosols produced in a radio frequency capacitively coupled plasma (RF-CCP). The influence of the gas mixture on aerosols spectra is also studied through the analysis of the carbonaceous bands of the spectra, and its Gaussian deconvolution. Представлен анализ в среднем инфракрасном диапазоне аналогов титановых аэрозолей, которые производятся в радиочастотных источниках плазмы с емкостной связью (РЧ-ЕСС). Также изучено влияние газовой смеси на спектры аэрозолей с помощью анализа углеродсодержащих полос спектра и ее гауссовой деконволюции (обратная свертка). Представлено аналіз у середньому інфрачервоному діапазоні аналогів титанових аерозолів, які проводяться в радіочастотних джерелах плазми з ємнісним зв'язком (РЧ-ЕСС). Також вивчено вплив газової суміші на спектри аерозолів за допомогою аналізу вуглецевмісних смуг спектра і її гауссової деконволюції (зворотня згортка). 2013 2013 Article Use of the linear absorption coefficient for absolute comparison of plasma films in the mid-IR range / T. Gautier, N. Carrasco, A. Mahjoub, I. Stefanovic, C. Szopa, G. Cernogora, E. Hadamcik, J. Winter // Вопросы атомной науки и техники. — 2013. — № 1. — С. 168-170. — Бібліогр.: 12 назв. — англ. 1562-6016 PACS: 52.25.-b http://dspace.nbuv.gov.ua/handle/123456789/109261 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Низкотемпературная плазма и плазменные технологии Низкотемпературная плазма и плазменные технологии |
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Низкотемпературная плазма и плазменные технологии Низкотемпературная плазма и плазменные технологии Gautier, T. Carrasco, N. Mahjoub, A. Stefanovic, I. Szopa, C. Cernogora, G. Hadamcik, E. Winter, J. Use of the linear absorption coefficient for absolute comparison of plasma films in the mid-IR range Вопросы атомной науки и техники |
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In this work, we present the mid-infrared analysis of analogues of Titan's aerosols produced in a radio frequency capacitively coupled plasma (RF-CCP). The influence of the gas mixture on aerosols spectra is also studied through the analysis of the carbonaceous bands of the spectra, and its Gaussian deconvolution. |
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Article |
| author |
Gautier, T. Carrasco, N. Mahjoub, A. Stefanovic, I. Szopa, C. Cernogora, G. Hadamcik, E. Winter, J. |
| author_facet |
Gautier, T. Carrasco, N. Mahjoub, A. Stefanovic, I. Szopa, C. Cernogora, G. Hadamcik, E. Winter, J. |
| author_sort |
Gautier, T. |
| title |
Use of the linear absorption coefficient for absolute comparison of plasma films in the mid-IR range |
| title_short |
Use of the linear absorption coefficient for absolute comparison of plasma films in the mid-IR range |
| title_full |
Use of the linear absorption coefficient for absolute comparison of plasma films in the mid-IR range |
| title_fullStr |
Use of the linear absorption coefficient for absolute comparison of plasma films in the mid-IR range |
| title_full_unstemmed |
Use of the linear absorption coefficient for absolute comparison of plasma films in the mid-IR range |
| title_sort |
use of the linear absorption coefficient for absolute comparison of plasma films in the mid-ir range |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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2013 |
| topic_facet |
Низкотемпературная плазма и плазменные технологии |
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http://dspace.nbuv.gov.ua/handle/123456789/109261 |
| citation_txt |
Use of the linear absorption coefficient for absolute comparison of plasma films in the mid-IR range / T. Gautier, N. Carrasco, A. Mahjoub, I. Stefanovic, C. Szopa, G. Cernogora, E. Hadamcik, J. Winter // Вопросы атомной науки и техники. — 2013. — № 1. — С. 168-170. — Бібліогр.: 12 назв. — англ. |
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Вопросы атомной науки и техники |
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2025-07-07T22:49:31Z |
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| fulltext |
168 ISSN 1562-6016. ВАНТ. 2013. №1(83)
USE OF THE LINEAR ABSORPTION COEFFICIENT FOR ABSOLUTE
COMPARISON OF PLASMA FILMS IN THE MID-IR RANGE
T. Gautier1,2, N. Carrasco1, A. Mahjoub1, I. Stefanovic2, C. Szopa1, G. Cernogora1,
E. Hadamcik1, J. Winter 2
1Université de Versailles St Quentin, CNRS, LATMOS 11bvd d'Alembert,
Guyancourt, France ;
2Experimental Physik II, Ruhr Universität Bochum, Bochum, Germany
In this work, we present the mid-infrared analysis of analogues of Titan's aerosols produced in a radio frequency
capacitively coupled plasma (RF-CCP). The influence of the gas mixture on aerosols spectra is also studied through
the analysis of the carbonaceous bands of the spectra, and its Gaussian deconvolution.
PACS: 52.25.-b
INTRODUCTION
Titan’s atmosphere is the place of a complex organic
chemistry initiated from dissociation of its main
constituents, i.e. N2 and CH4. This chemistry leads to the
formation of solid aerosols and can be simulated in
laboratory using a RF-CCP setup [1].
In this work we propose a method for infrared analyses
that allows direct comparison of different samples. This
method is used for the analysis of the carbon-hydrogen
bonding in the organic material produced with the
plasma.
1. THE PAMPRE EXPERIMENT
Fig. 1 present the experimental setup. The reaction
chamber is a stainless-steel cylinder 30 cm in diameter
and 40 cm in height. The plasma is confined in a
metallic box 13.7 cm in diameter and with a 4…5 cm
inter-electrode gap (Confining Box CB) . The bottom of
the box is meshed to allow sweeping the dust out. On
the side of the box, two 1 cm-wide apertures, covered
with a thin grid, allow studying the plasma using optical
emission spectroscopy (OES) using a -UV-VIS-NIR
Monochromator (SP) fitted with a - Photomultiplier;
(PM) and a Picoampmeter (PA) [2]. This configuration,
already used in the GREMI laboratory [3] is known to
produce dust in a reactive gas mixture [4]. Other
available diagnosis are, FTIR, mass spectrometry [5],
cryogenic trapping associated to gas chromatography-
mass spectrometry [6], the electron density
measurements using the confining box as a resonant
microwave cavity and the self-bias voltage (Vdc).
Fig. 1. Experimental setup of the PAMPRE experiment
Before production of samples, the reactor is heated
and pumped with a turbo molecular pump (TP) down to
a secondary vacuum measured with a penning gauge
(PG).
Reactive gas (i.e. mixture of N2 and CH4) is injected
through a shower head located above the top electrode
using mass flow controllers (MFC) and pumped by a
rotary vane pump (RVP). Pressure is measured with a
capacitance gauge (BPG). Organic solid material are
produced at room temperature, with a pressure of 90 Pa
and a gas mixture varying from 1 to 10 % of CH4 in N2.
Samples can be produced either as bulk dust or
deposited as thin films on substrates placed on the
confining box, directly inside the plasma. Tholins
analyzed in this work were deposited as thin film on
low-emissivity infrared mirror (MirrIR™).
2. SAMPLE ANALYSIS AND DISCUSSION
Analyses of organic film absorption in the Infrared
were performed at the SMIS beamline of SOLEIL
synchrotron facility, France [7]. We used a NicPlan
microscope coupled to a Nicolet Magna System 560
Fourier Transformed Infrared spectrometer. The
Infrared source was the synchrotron radiation and the
detector was a Mercury-Cadmium Telluride (MCT)
detector. Infrared spectra were performed in double
transmission mode.
Spectra were recorded at a spectral resolution of
4 cm-1 after co-adding 512 scans at a Michelson mirror
velocity of 1.26 cm·s-1. Spectra cover the full mid and
far infrared range, from 50 cm-1 (200 µm) up to
4500 cm-1 (2.2 µm). This work will focus on the
2800...3000 cm-1 wavenumber range, corresponding to
the aliphatic carbons bands.
In order to compare several samples, it is needed to
calibrate absorption spectra according to the thickness
of the films. Indeed, after absorption in the sample, the
intensity of the beam follows the Beer-Lambert law that
can be established as:
.
Where d is the sample thickness, It the intensity of
the transmitted beam, I0 the initial intensity and ε is the
linear absorption coefficient of the material.
ISSN 1562-6016. ВАНТ. 2013. №1(83) 169
As film thickness d (a few hundreds nanometers)
varies with discharges conditions, d is measured for
each sample by ellipsometry [8].
The full spectra in the mid-infrared of tholins is
presented Fig. 2.
The different curves correspond to spectra of tholins
produced with different gas mixtures (respectively 1, 2,
5 and 10 % of CH4 in N2). These spectra present
common tholins absorption features in the mid-infrared,
widely described in literature [9-11].
1500 2000 2500 3000 3500
0
500
1000
1500
2000
2500
3000
3500
ν (cm-1)
ε
(c
m
-1
)
1%
2%
5%
10%
Fig. 2. Spectra of tholins produced with different gas
mixture. Full black curve: 1 % CH4; Dashed black: 2 %
CH4; Dashed grey: 5% CH4; Full grey: 10% CH4.
Adapted from [11]
Two broad bands coming from amine (-NH and –
NH2) stretching modes are visible at high wavenumber
(3200 and 3330 cm-1). Close to these bands is the
pattern attributed to aliphatic carbons (-CH2 and –CH3)
stretching modes, around 2900 cm-1. This pattern will be
discussed in details lately. The three bands observed
around 2200 cm-1 can be attributed to nitriles (-C=-N),
isocyanides (-N=-C) and carbodiimide (-N=C=N-)
stretching modes. Finally, the intense bands at 1560 and
1630 cm-1 cannot be unambiguously attributed since
they could correspond to several functional groups
bending modes such as –NH2, C=C, C=N or aromatics.
To study the impact of methane percentage in the
experiment on aliphatic carbon contain, we used a poly-
Gaussian deconvolution (performed with fityk software)
of the 2900 cm-1 pattern as proposed in [9].
In order to study this pattern, it was first necessary to
remove the component due to the presence of amines
bands at higher wavenumbers, considering this amine
band as a baseline for the aliphatic carbons bands. This
means that the pattern visible on Fig. 2 is only due to
the contribution of aliphatic carbons (-CH2 and –CH3)
bands. This 2800…2900 cm-1 pattern is fitted by a
combination of Gaussian functions. In this spectral
range, there are up to five possible stretching modes for
C-H bonding, corresponding to –CH3 asymmetric
(~2970 cm-1); -CH2 asymmetric (~2930 cm-1); -CH
(~2900 cm-1); -CH3 symmetric (~2870 cm-1) and –CH2
symmetric (~2850 cm-1).
The fitting process was thus initialized with five
Gaussians at these positions. Figs. 3 and 4 present the fit
for samples produced with 1 and 10 % CH4. Dots are
the experimental spectra, dashed lined are the Gaussians
used for the fit, and full line is the resulting model.
2800 2850 2900 2950 3000 3050
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
ν (cm-1)
ε
(c
m
-1
)-
B
as
el
in
e
su
bs
tra
ct
ed
Experimental data (1% CH4)
Gauss1
Gauss2
Gauss3
Gauss4
Fit
Fig. 3. Deconvolution of films 1% CH4 -spectrum
2750 2800 2850 2900 2950 3000 3050 3100
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
ν (cm-1)
ε
(c
m
-1
)-
B
as
el
in
e
su
bs
tra
ct
ed
Experimental data (10% CH4)
Gauss1
Gauss2
Gauss3
Fit
Fig. 4. Deconvolution of films 10 % CH4-spectrum
The first information in this plot is the global
intensity of this pattern, which regularly increases with
the methane percentage in the experiment. Indeed, εmax
is around 1.10-2 cm-1 for 1 % CH4, 4.10-2 cm-1 for 2 %
CH4, 6.10-2 cm-1 for 5 % CH4 and 9.10-2 cm-1 for 10 % of
CH4 in the experiment. This means that the global
amount of aliphatic carbon in tholins increases with the
percentage of methane in the mixture used to produce
tholins. This is also consistent with the decrease of
amines bands when CH4 increases in the experiment,
visible on Fig. 2.
Secondly, as visible on these figures, most part of the
signal comes from only three of the Gaussians,
corresponding to –CH2 asymmetric and –CH3
symmetric and asymmetric stretching. Looking to the
respective weight of these three Gaussians in the fit, one
can see that the –CH2 are the predominant bonding in
tholins produced with 1 % of CH4. But when methane
percentage increases, –CH3 become slightly more
abundant than –CH2. This augmentation is consistent
with elemental analysis performed previously on tholins
[12] which showed that the H/C ratio in tholins
increases with methane percentage.
CONCLUSIONS
In the present work, the proposed method for
infrared analysis of organic thin film allows quantitative
comparison of different samples.
The comparison of spectra of thin film produced
with different methane percentage shows the decreases
of amine bands and increases of carbon bands, and also
the evolution of the 2900 cm-1 pattern.
REFERENCES
1. C. Szopa, G. Cernogora, L. Boufendi, J.J. Correia and
P. Coll. PAMPRE: A dusty plasma experiment for
Titan's tholins production and study // Planetary and
Space Science. 2006, v. 54, p. 394-404.
170 ISSN 1562-6016. ВАНТ. 2013. №1(83)
2. G. Alcouffe, M. Cavarroc, G. Cernogora, F. Ouni,
A. Jolly, L. Boufendi and C. Szopa. Capacitively
coupled plasma used to simulate Titan's atmospheric
chemistry // Plasma Sources Science and Technology.
2010, v. 19(1), p. 015008.
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Plasma Sources Sci. Technol. 1994, v. 3(3), p. 262.
4. A. Bouchoule. Dusty Plasmas: Physics, Chemistry,
and Technological Impact in Plasma Processing / Ed.
Wiley, 1999, p. 418.
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G. Cernogora. Volatile products controlling Titan’s
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E. Sciamma-O'Brien and G. Cernogora. Nitrile gas
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J.L. Giorgetta and S. Lefrançois. Synchrotron infrared
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// Infrared Physics & Technology. 2006, v. 49(1-2),
p. 152-160.
8. A. Mahjoub, P.R. Dahoo, T. Gautier, N. Carrasco,
C. Szopa and G. Cernogora. Influence of methane
concentration on the optical indices of Titan's aerosols
analogues // Icarus. 2012, v. 221(2), p. 670-677.
9 H. Imanaka, B.N. Khare, J.E. Elsila, E.L.O. Bakes,
C.P. McKay, D.P. Cruikshank, S. Sugita, T. Matsui and
R.N. Zare. Laboratory experiments of Titan tholin
formed in cold plasma at various pressures: implications
for nitrogen-containing polycyclic aromatic compounds
in Titan haze // Icarus. 2004, v. 168, p. 344-366.
10. E. Quirico, G. Montagnac, V. Lees, P.F. McMillan,
C. Szopa, G. Cernogora, J.-N. Rouzaud, P. Simon,
J.-M. Bernard, P. Coll, N. Fray, R.D. Minard, F. Raulin,
B. Reynard and B. Schmitt. New experimental
constraints on the composition and structure of tholins //
Icarus. 2008, v. 198(1), p. 218-231.
11. T. Gautier, N. Carrasco, A. Mahjoub, S. Vinatier,
A. Giuliani, C. Szopa, C.M. Anderson, J.-J. Correia,
P. Dumas and G. Cernogora. Mid- and far-infrared
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Icarus. 2012, v. 221(1), p. 320-327.
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Article received 22.11.12
ИСПОЛЬЗОВАНИЕ ЛИНЕЙНОГО КОЭФФИЦИЕНТА ПОГЛОЩЕНИЯ ДЛЯ АБСОЛЮТНОГО
СРАВНЕНИЯ ПЛАЗМЕННЫХ ПЛЕНОК В СРЕДНЕМ ИК-ДИАПАЗОНЕ
T. Gautier, N. Carrasco, A. Mahjoub , I. Stefanovic, C. Szopa, G. Cernogora, E. Hadamcik, J. Winter
Представлен анализ в среднем инфракрасном диапазоне аналогов титановых аэрозолей, которые
производятся в радиочастотных источниках плазмы с емкостной связью (РЧ-ЕСС). Также изучено влияние
газовой смеси на спектры аэрозолей с помощью анализа углеродсодержащих полос спектра и ее гауссовой
деконволюции (обратная свертка).
ВИКОРИСТАННЯ ЛІНІЙНОГО КОЕФІЦІЄНТА ПОГЛИНАННЯ ДЛЯ АБСОЛЮТНОГО
ПОРІВНЯННЯ ПЛАЗМОВИХ ПЛІВОК У СЕРЕДНЬОМУ IЧ-ДІАПАЗОНІ
T. Gautier, N. Carrasco, A. Mahjoub. , I. Stefanovic, C. Szopa, G. Cernogora, E. Hadamcik, J. Winter
Представлено аналіз у середньому інфрачервоному діапазоні аналогів титанових аерозолів, які
проводяться в радіочастотних джерелах плазми з ємнісним зв'язком (РЧ-ЕСС). Також вивчено вплив газової
суміші на спектри аерозолів за допомогою аналізу вуглецевмісних смуг спектра і її гауссової деконволюції
(зворотня згортка).
|