Journal of Quantitative Spectroscopy & Radiative Transfer 117 (2013) 21–28
Contents lists available at SciVerse ScienceDirect
Journal of Quantitative Spectroscopy &
Radiative Transfer
journal homepage: www.elsevier.com/locate/jqsrt
Experimental CO2 absorption coefficients at high pressure
and high temperature
Stefania Stefani a,n, Giuseppe Piccioni a, Marcel Snels a,b, Davide Grassi a,
Alberto Adriani a
a
b
Institute of Astrophysics and Planetary Science, Via Fosso del cavaliere 100, Rome, Italy
Institute of Atmospheric Science and Climare, Via Fosso del cavaliere 100, Rome, Italy
a r t i c l e i n f o
abstract
Article history:
Received 18 July 2012
Received in revised form
7 November 2012
Accepted 19 November 2012
Available online 27 November 2012
Here we present a laboratory study of CO2 absorption spectra, obtained at high
temperatures and pressures, similar to those encountered in the Venusian atmosphere.
These spectra have been recorded using a Fourier Transform InfraRed (FT-IR) spectrometer , which is equipped to operate from 800 to 30,000 cm 1 (0:33212:5 mm) with
a resolution from 0.06 to 10 cm 1. A dedicated gas cell, designed to support pressures up
to 200 bar and temperatures up to 350 1C, has been coupled to the FT-IR. Starting from a
realistic vertical pressure–temperature profile of the Venus’ atmosphere, based on
measurements performed with atmospheric probes, we have recorded a series of
absorption spectra of CO2, varying the pressure and temperature from 1 to 50 bar and
from 294 to 650 K.
& 2012 Elsevier Ltd. All rights reserved.
Keywords:
Planetary atmosphere
Absorption coefficients
Carbon dioxide
Radiative transfer
Venus
1. Introduction
The study of planetary atmospheres is often based on
transmission and absorption spectra obtained by space
borne instruments. These spectra, mostly in the visible
and infrared spectral range, provide a multitude of data,
concerning the composition and physical conditions of
the atmosphere, the presence of clouds, dynamical processes and surface properties. In order to extract these
physical and chemical parameters, a radiative transfer
model has to be used, based on spectroscopic parameters
and scattering properties of the atmospheric constituents.
Presently a wealth of spectroscopic data are present in
several databases, such as HIgh-resolution- TRANsmission
(HITRAN [1]), HIgh-TEMPerature (HITEMP [2]) CarbonDioxide-Spectroscopy-Databank (CDSD [3]).
They provide a suite of parameters for the most
common molecular species at typically terrestrial
n
Corresponding author.
E-mail address: [email protected] (S. Stefani).
0022-4073/$ - see front matter & 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.jqsrt.2012.11.019
conditions and in combination with theoretical models a
satisfactory simulation of the absorption by a planetary
atmosphere in pressure and temperature conditions similar to the earth’s atmosphere can be performed.
On the contrary, the available molecular parameters
and the present theoretical models are insufficient for an
accurate simulation of the absorption spectra of gases in
extreme conditions. For example, when studying planetary atmospheres at high pressure and temperature, one
must take into account pressure induced effects such as
line mixing, far wings absorption and collision induced
absorption. The dense atmosphere of Venus, consisting for
97% of carbon dioxide, provides an interesting laboratory
for studying these processes and testing the efficiency of
the radiative transfer models. The study of the absorption
properties of CO2 at high pressure and temperature is of
fundamental interest for a correct interpretation of the
data provided by the VIRTIS (Visible and InfraRed Thermal
Imaging Spectrometer) instrument on board the ESA
mission Venus Express [4]. VIRTIS provides hyper spectral
images of the Venus’ atmosphere covering the spectral
range from 0.3 to 5:1 mm. Radiative transfer models used
22
S. Stefani et al. / Journal of Quantitative Spectroscopy & Radiative Transfer 117 (2013) 21–28
to analyze this spectra, need molecular parameters and
sophisticated line broadening models in order to calculate
the transmission of the dense and hot atmosphere of
Venus. It is well known that the carbon dioxide atmosphere is responsible for the greenhouse effect of Venus
and inhibits large part of the radiation coming from the
surface of reaching space. Apart from this, sulfuric acid
clouds form an efficient shield which prevent a direct
view of the surface in the visible domain and actually –
until the first UV telescope started looking at the planet –
the complicated patterns created by the cloud motions
were thought to belong to the planetary surface. Carbon
dioxide is a strong absorber in the infrared and near infra
red part of the spectrum, and observations below the
clouds and of the surface is only possible in the so-called
‘‘transparency windows’’ in between the strong absorption bands. Up to now, accurate experimental CO2 absorption coefficients at high pressure and high temperature
are missing. The high densities present in the Venus’
atmosphere give rise to different phenomena. First of all,
the collisional broadening of the spectral transitions
render the spectral line shapes non-Lorentzian. This effect
is usually described in terms of far wings or continuum
absorption and has been hitherto treated in a semiempirical way. On the other hand , so-called line-mixing
or interference of rotational states leads to transfer of
intensity from the ‘‘wings’’ of an absorption band to the
center wavelengths. From a theoretical point of view a
satisfactory model is available to describe line-mixing
processes for the CO2 at high pressure and high temperature [5]. This model has been successfully used to simulate a large number of data recorded for high densities
and temperatures, including a large number of spectra
presented here. A third phenomenon, occurring at high
densities is the Collision-Induced Absorption (CIA) [6]
which renders active absorption bands which are not
allowed in the IR.
The present work intends to provide new laboratory
data in support of space missions, to make high pressure
and temperature spectra of CO2 available to the planetary
atmosphere community and might also provide data to
the new CIA HITRAN data base [7]. Here we present some
of the spectra of CO2 recorded in the spectral range from
800 to 10,000 cm 1 at different combined high pressure
and high temperature conditions in order to illustrate
some of the main features of a high pressure, high
temperature atmosphere, such as collisional broadening,
far wing absorption and collision induced absorption
bands. With our experimental setup, we recreated the
same conditions found in the deep atmosphere of Venus,
varying the pressure and temperature according to the
Venus International Reference Atmosphere (VIRA) profile
[8]. The recorded spectra provide information on the
optical properties of CO2 in the Venus’ atmosphere from
an altitude of 50 down to 22 Km.
2. Experimental setup
The experimental set up consists of a Fourier Transform InfraRed (FT-IR) interferometer (& Bruker model
Vertex80) and a commercial high pressure and high
temperature gas cell (& AABSPEC, model # 2T-AWT).
The FT-IR is equipped with an air-cooled Tungsten lamp
emitting in the Visible/Near-InfraRed and a Globar source
providing Mid-InfraRed radiation. By combining four
different detectors and two different beam splitters,
CaF2 and KBr, respectively, the instrument covers the
spectral range from 800 to 30,000 cm 1.
Inside the sample compartment of the interferometer,
the high pressure-high temperature (HP-HT) gas cell,
constructed from a single piece of 316 grade stainless
steel, was mounted.
The cell is composed of three separate compartments
and equipped with ZnS windows of 13 mm in diameter
and 5 mm in thickness. The window material provides a
good transmission in the NIR and MIR spectral range and
has excellent mechanical and thermal properties. The
central compartment with an optical path of about 2 cm
supports pressures up to 200 bar and temperatures up to
650 K. The external compartments are kept at near
ambient temperature, by water cooling, and are filled
with a low thermal conductivity non-absorbing gas
(usually Ar), at the same pressure as the central compartment. In this way the pressure difference with respect to
the ambient air is acting on the two external windows at
room temperature, while the two internal windows are
only exposed to a temperature difference.
In order to investigate the spectral range of interest,
we used the tungsten lamp, CaF2 beam splitter and the
InGaAs detector from 6000 to 10,000 cm 1 and the Globar
source, KBr beam splitter and the MCT detector from 800
to 6000 cm 1. Each spectrum results from the addition of
150 scans acquired with a resolution of 2 cm 1. To obtain
the CO2 transmittance, we adopted the following procedure: the secondary chambers are water cooled while the
primary section is heated up to the target temperature.
First all three sections are charged with Ar at the preset
pressure and a reference background is recorded. The Ar
in the central section is then removed and replaced by
CO2 at the same pressure and the absorption spectrum is
recorded. This procedure has been applied to all measurements. In these experiments high purity CO2 gas has been
used (99.995%). To measure the temperature in the
absorption cell and in the buffer sections two type-K
thermocouples were used. Two gauges (model EPXT-P0)
have been used to measure the pressures of the carbon
dioxide and Ar gas.
3. Results and discussion
We recreate the same conditions observed in the deep
atmosphere of Venus as specified by the Venus International
Reference Atmosphere (VIRA) [8]. In order to reproduce a
realistic vertical pressure–temperature profile, we varied
the pressure and temperature of the CO2 from 1 to 20 bar
and from 349 to 565 K, respectively. This corresponds to an
altitude from about 50 km down to 22 km (see Fig. 1).
Fig. 2 shows how the spectra change shape in different
spectral ranges, in function of the altitude on the VIRA
profile, from 22 to 32 km.
Note how the intensity and the width of the absorption
bands increase while going towards the surface of Venus,
S. Stefani et al. / Journal of Quantitative Spectroscopy & Radiative Transfer 117 (2013) 21–28
due to the increasing densities and temperatures. While
some of the rovibrational structure of the CO2 spectra can
still be resolved for pressures up to about 6 bar, for higher
densities the line broadening smears out the spectral
structure due to collision broadening.
All bands displayed in Fig. 2 are due to dipole allowed
transitions, and although the shape of the bands changes
Fig. 1. Altitude versus pressure according to the VIRA model. CO2
absorption coefficients have been measured for pressures and temperatures corresponding with altitudes of 22–50 km with respect to the
surface of Venus.
23
with temperature and pressure, the integrated absorption
of each band is expected to be proportional to the number
density. In order to verify this behavior, we have calculated the integrated band intensity in different spectral
regions, for a range of pressures and temperatures corresponding with the VIRA profile. The linear behavior of the
integrated band intensity with density shows that absorption in these spectral ranges is mainly due to allowed
absorption bands (see Fig. 3).
The straight lines correspond with an integrated band
intensity of 1.68 and 0.045 cm 2 atm 1 at 294 K, for the
spectral ranges 4750–5200 and 6850–7200 cm 1, respectively, in good agreement with Ref. [9].
A complete list of pressure and temperature values for
which the absorption spectra have been recorded can be
found in Appendix A. Ascii files of the CO2 absorption
coefficients measured can be down loaded from the web
site: http://exact.iaps.inaf.it.
For any given temperature and pressure the density of
a gas can be calculated using more or less approximate
methods. The ideal gas law is valid only for low densities,
and cannot be used here. The Van der Waals equation
provides a better approximation, taking into account the
intermolecular forces and providing a correction for finite
molecular size and can be written as
n2 a
p þ 2 ðVnbÞ ¼ nRT
V
ð1Þ
Fig. 2. CO2 absorption spectra at different pressures and temperatures. The pressure and temperature values correspond to an altitude of 32 km down to
22 km, according to the VIRA model.
24
S. Stefani et al. / Journal of Quantitative Spectroscopy & Radiative Transfer 117 (2013) 21–28
Fig. 3. Band integrated area versus density (black squares) and linear fit of the data(line). Note that there is a slight deviation for the highest densities,
because a small part of the integrated band intensity is outside of the integration window.
where p is the pressure, T the temperature, V the volume
and n the number of moles, and R is the ideal gas constant
(8.314 J K 1 mol 1), a is a constant that takes into account
the intermolecular forces and b provides a correction for
finite molecular size.
The virial expansion, also called the virial equation of
state is the best approximation for solving the equation of
state for a real gas. The virial expansion is a power series
in (n/V ) and has the form
n
n 2
pV
¼ 1þ BðTÞ
þCðTÞ
þ nRT
V
V
ð2Þ
where p is the pressure, T the temperature, R is the ideal
gas constant and (V /n) is the molar volume. B(T) and C(T)
are the second and third order virial coefficients, respectively, and depend on T. For all measurements performed
in the present work, the density reported has been
obtained from a facility provided by the National Institute
of Standards and Technology, which uses the virial expansion up to the third virial coefficient [10].
As stated before, the main goal of this paper is to provide
a data base containing the experimental absorption coefficients of carbon dioxide in the spectral range 800–
10,000 cm 1, in particular referred to planetary atmospheres with high pressures and temperatures, similar to
the Venus’ atmosphere. In a previous work, a sophisticated
model, including line broadening effects, line mixing and far
wings, but neglecting collision induced bands, was used to
simulate a series of spectra, as recorded experimentally,
both by us and the group in Paris, for selected spectral
ranges. The model provided excellent results [5] and can be
used to extend the experimental data base for different
temperatures and pressures. We’ve measured the carbon
dioxide spectra for conditions similar to those reported by
Seiff et al. [8], (the so-called VIRA model for the Venus’
atmosphere) in order to extrapolate and interpolate
between experimental spectra , using the model reported
in [5].
For this purpose, while maintaining the CO2 density
fixed to that of the VIRA profile, we’ve varied the temperature by 730 1C with respect to the original profile,
and calculated the pressure according to Eq. (2). In this
way, we have obtained two new profiles of temperature
and pressure, as shown in Fig. 4.
For each point of this grid, we recorded the CO2 absorption spectra, acquired in the spectral range from 800 to
10,000 cm 1 and with the same experimental parameters as
before , i.e resolution 2 cm 1, and 150 scans. In a forthcoming work, the carbon dioxide absorption coefficients,
obtained from the data base presented here, eventually
interpolated or extrapolated where necessary, will be
inserted in a radiative transfer model, in order to compare
the calculation with observed VIRTIS spectra.
3.1. Collisional induced absorption (CIA)
Carbon dioxide is a linear triatomic molecule that has
3 3 5¼4 normal modes of vibration. The normal
modes are conventionally labeled n1 , n2 and n3 , with n2
referring to the degenerate bending mode, n3 is the asymmetric stretching mode and n1 the symmetric stretching
mode. While n2 and n3 have a transition dipole moment and
S. Stefani et al. / Journal of Quantitative Spectroscopy & Radiative Transfer 117 (2013) 21–28
are thus infrared active, n1 does not possess a transition
dipole moment and does not absorb in the infrared. This
statement holds for low density, but for higher densities
collisions may induce a dipole moment which leads to
absorption. This so-called collision induced absorption
Fig. 4. The three pressure- temperature profiles, with the same density
as the VIRA profile. The black curve is the VIRA profile, the dotted line is
obtained decreasing T by 301C and the dash-dot is obtained increasing T
by 301C. CO2 absorption coefficients have been recorded for all three
profiles.
25
(CIA), being originated by n-body collisions is proportional
to the nth power of the density and can be observed already
at pressures of about a few bar. By employing our experimental set-up, we observed several absorption bands due to
CIA, as can be seen in Fig. 5. According to Baranov and
Vigasin [11], who performed an extensive study of the
collision induced absorption bands, the band observed in
the spectral range [1200–1500] cm 1 is due to the strong
Fermi-coupled doublet (n1 , 2n2 ). The spectrum consist of
two bands, one at about 1282 cm 1 and the second one at
about 1390 cm 1.
Different hypotheses have been proposed in order to
explain the presence of these bands and their temperature dependence, including that of dimer formation.
Vigasin et al. [12], observing CO2 absorption using the
Coherent Anti-Stokes Raman Scattering (CARS) technique,
assigned a peak at 1284.73 cm 1 to the carbon dioxide
dimer.
It is clear that at high densities bound or quasi bound
complexes may be formed and give rise to absorption, but
the hypothesis that dimer absorption alone can be held
responsible for the collision induced absorption is questionable. In the first place, dimer spectra are shifted with
respect to the (inactive) monomer absorption and thus
one would expect to observe a shift. Secondly, one would
expect to observe larger clusters as well, having complex
structures and spectra.
Fig. 5. Collision Induced Absorption (CIA) bands observed at room temperature and different pressures (3, 10, 20, 30 and 40 bar)(panels a and c) and at
different temperatures (294, 373 and 473 K) (panels b and d) with a pressure of about 40 bar.
26
S. Stefani et al. / Journal of Quantitative Spectroscopy & Radiative Transfer 117 (2013) 21–28
Fig. 6. The band integrated area vs density evaluated for the spectral range [1200–1500]cm 1 (top) and for [2900–3100] cm 1 (bottom). The squares,
stars and triangles correspond to a quadratic dependence on the density.
Table A1
List of experimental pressure and temperatures, for which spectra were recorded in the NIR and MIR configurations. The temperatures and pressures are
according to the VIRA profile. The first column is the altitude in km.
km
NIR
p (bar)
50
49
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
1.12 7 0.01
1.22 7 0.05
1.36 7 0.01
1.50 7 0.01
1.705 7 0.003
1.962 7 0.001
2.27 7 0.01
2.57 7 0.03
2.77 7 0.02
3.093 7 0.001
3.453 7 0.002
3.842 7 0.001
4.400 7 0.001
4.877 7 0.002
5.314 7 0.001
5.842 7 0.001
6.464 7 0.001
7.246 7 0.002
7.808 7 0.003
8.747 7 0.002
9.579 7 0.001
10.583 7 0.003
11.579 7 0.003
12.567 7 0.003
13.656 7 0.002
14.872 7 0.009
16.319 7 0.007
17.694 7 0.005
19.225 7 0.009
MIR
T (K)
348.9 7 0.6
358.2 7 0.5
364.6 7 0.3
370.13 7 0.04
375.9 7 0.02
383.1 7 0.1
388.91 7 0.07
395.3 7 0.2
401.9 7 0.1
408.4 7 0.1
415.4 7 0.1
423.14 7 0.09
430.9 7 0.2
438.9 7 0.3
446.8 7 0.1
455.1 7 0.1
463.3 7 0.3
471.3 7 0.2
477.3 7 0.1
488.7 7 0.1
498.4 7 0.2
506.37 0.2
513.7 7 0.2
521.9 7 0.2
530.5 7 0.1
539.04 7 0.08
545.6 7 0.4
556.7 7 0.2
565.1 7 0.4
p (bar)
1.0842 7 0.0008
0.235 7 0.001
1.3567 7 0.0008
1.58 7 0.07
1.7445 7 0.0009
1.9796 7 0.0009
2.250 7 0.001
2.4391 7 0.0009
2.709 7 0.001
3.144 7 0.001
3.469 7 0.001
3.79 7 0.01
4.40 7 0.01
4.823 7 0.003
5.323 7 0.001
5.85 7 0.01
6.647 7 0.001
7.18 7 0.01
7.821 7 0.002
8.706 7 0.001
9.495 7 0.004
10.499 7 0.001
11.494 7 0.002
12.628 7 0.009
13.781 7 0.001
14.980 7 0.004
16.166 7 0.002
17.561 7 0.002
19.284 7 0.003
T (K)
349.25 7 0.07
357.35 7 0.07
364.6 7 0.1
369.85 7 0.8
375.4 7 0.1
381.4 7 0.1
388.61 7 0.09
394.5 7 0.1
401.74 7 0.09
408.4 7 0.2
415.9 7 0.1
423.4 7 0.2
430.9 7 0.3
438.5 7 0.3
446.8 7 0.1
454.1 7 0.2
463.61 7 0.09
471.35 7 0.08
478.3 7 0.1
488.6 7 0.2
497.4 7 0.3
506.3 7 0.1
513.81 7 0.06
523.9 7 0.5
530.5 7 0.4
539.1 7 0.2
546.9 7 0.2
555.7 7 0.2
565.6 7 0.4
S. Stefani et al. / Journal of Quantitative Spectroscopy & Radiative Transfer 117 (2013) 21–28
The integrated intensities of the observed bands
depend on the n-th power of the density, which in our
measurements is approximately a quadratic dependence
versus density, as can be observed in Fig. 6. The limited
number of data, in terms of integrated absorption versus
density, does not allow to separate quadratic and cubic
and higher order dependencies on the densities. A log–log
plot of integrated absorption intensity versus density
produces a power which is close to two, confirming that
the dependence is in good approximation quadratic.
4. Conclusions
An extensive set of absorption spectra of CO2 at
temperatures and pressures similar to those found in
the Venus’ atmosphere has been recorded and is made
available to the scientific community. In a previous work
a theoretical model including line mixing and a semiempirical model taking into account far wing absorption
has been shown to be in excellent agreement with
experimental data. In order to facilitate interpolation
and/or extrapolation towards different pressures and
temperatures, additional CO2 spectra have been recorded
at temperatures 30 1C above and below the the VIRA
profile. Some collision induced bands have been recorded
as well, for different temperatures and pressures. For
what concerns the temperature dependence, the intensity
of the CIA bands decreases slightly going from 294 K to
473 K and requires further investigations, as well as the
study of weaker CIA bands, using longer absorption path
Table A2
List of experimental pressure and temperatures, for which spectra were
recorded in the NIR and MIR configurations. The temperatures are 30 1C
below the VIRA profile.
NIR
p (bar)
1.187 70.001
1.308 70.001
1.499 70.002
1.680 70.001
1.840 70.001
2.117 70.001
2.425 70.002
2.644 70.001
3.095 70.001
3.373 70.001
3.77 70.03
4.137 70.004
4.627 70.009
5.116 70.004
5.86 70.04
6.312 70.006
6.7 70.2
7.699 70.009
7.469 70.001
8.406 70.003
9.19 70.01
10.026 70.004
11.091 70.002
12.047 70.002
13.254 70.002
14.552 70.009
MIR
T (K)
378.7 7 0.03
387.187 0.02
393.937 0.09
399.897 0.05
405.57 7 0.05
411.257 0.1
418.4 7 0.1
424.2 7 0.1
431.387 0.08
438.4 7 0.2
445.957 0.1
453.3 7 0.6
460.7 7 0.6
468 7 1
477.1 7 0.3
485 7 1
493 7 1
501.9 7 0.7
449.3 7 0.1
513.1 7 0.2
518.5 7 0.2
526.8 7 0.2
535.6 7 0.3
543.6 7 0.2
552.6 7 0.3
560.5 7 0.3
p (bar)
1.0842 70.0008
1.2889 70.0008
1.4995 70.0001
1.651 70.001
1.834 70.002
2.111 70.002
2.356 70.003
2.634 70.001
3.004 70.001
3.383 70.006
3.750 70.002
4.210 70.001
4.708 70.003
5.132 70.001
5.729 70.002
6.278 70.007
6.68 70.01
7.734 70.005
7.506 70.002
8.416 70.001
9.253 70.001
10.089 70.001
11.128 70.003
12.138 70.003
13.150 70.001
14.382 70.002
T (K)
378.7 7 0.1
387.237 0.08
394.3 7 0.1
399.947 0.09
406.08 7 0.09
410.19 7 0.04
417.277 0.02
424.827 0.09
432.05 7 0.04
433.2 7 0.2
445.4 7 0.06
452.457 0.002
461.03 7 0.03
468.117 0.03
473.8 7 0.1
483.5 7 0.1
493.537 0.01
498.327 0.05
449.257 0.01
510.1 7 0.2
518.5 7 0.2
526.8 7 0.2
545.5 7 0.5
543.5 7 0.5
552.5 7 0.3
560.6 7 0.3
27
lengths. Future efforts are directed towards the inclusion of
our experimental data in a radiative transfer model, in order
to improve the accuracy of remote sensing analysis of
planetary atmospheres.
Acknowledgments
The authors acknowledge Angelo Boccaccini for his
precious assistance in the experimental work and
Dr. Romolo Politi for setting up the web site. We also
acknowledge ASI for funding part of the work in the
framework of the ASI-projects VENUS-EXPRESS and JIRAM.
Appendix A
This appendix provides three tables with the experimental pressures and temperatures, corresponding to the VIRA
profile (Table A1) and to a modified VIRA profile with a
temperature 30 1C below (Table A2) and above (Table A3)
the VIRA profile. While maintaining the CO2 density fixed to
that of the VIRA profile the pressure has been calculated
using Eq. (2). Spectra have been recorded in two configurations, the NIR, employing the tungsten lamp, CaF2 beam
splitter and the InGaAs detector from 6000 to 10,000 cm 1
Table A3
List of experimental pressure and temperatures, for which spectra were
recorded in the NIR and MIR configuration. The temperatures are 30 1C
above the VIRA profile.
NIR
p (bar)
0.957 70.001
1.136 70.001
1.281 70.001
1.414 70.001
1.840 70.001
1.679 70.007
1.857 70.001
2.112 70.001
2.344 70.002
2.501 70.007
2.947 70.002
3.308 70.003
3.593 70.001
4.003 70.002
4.497 70.001
4.968 70.001
5.208 70.008
6.073 70.005
6.705 70.003
7.469 70.001
8.228 70.003
9.000 70.007
9.895 70.001
10.747 70.004
11.928 70.002
12.914 70.002
14.116 70.002
15.257 70.005
16.614 70.005
18.13 70.01
19.65 70.03
21.10 70.02
22.88 70.02
MIR
T (K)
7319.127 0.04
328.7 7 0.1
334.04 7 0.03
336.697 0.02
405.57 7 0.05
344.1 7 0.2
351.547 0.01
357.287 0.01
363.787 0.03
366.9 7 0.1
373.857 0.06
384.1 7 0.1
393.247 0.03
399.357 0.04
408.52 7 0.01
416.977 0.02
424.627 0.02
431.427 0.07
442.227 0.02
449.3 7 0.1
457.9 7 0.1
465.9 7 0.082
475.5 7 0.2
484.0 7 0.4
492.4 7 0.1
500.97 0.1
509.6 7 0.2
517.7 7 0.2
528.1 7 0.3
534.9 7 0.5
542.5 7 0.9
550.1 7 0.8
559.3 7 0.5
p (bar)
0.94 70.07
1.109 70.004
1.27 70.01
1.418 70.02
1.834 70.002
1.638 70.002
1.85 70.01
2.08 70.02
2.318 70.003
2.59 70.03
2.877 70.006
3.243 70.004
3.636 70.004
4.015 7 0.004
4.475 7 0.005
5.004 70.007
5.479 7 0.002
6.081 7 0.006
6.73 70.05
7.371 70.001
8.154 70.001
9.039 70.002
9.890 70.002
10.818 7 0.002
11.71570.002
12.820 70.001
14.17570.001
15.180 70.002
16.72370.006
18.15170.001
19.550 70.001
21.16570.006
22.97770.009
T (K)
319.657 0.7
328.8 7 0.8
334.1 7 0.5
338.6 7 0.2
406.08 7 0.09
344.5 7 0.4
351.7 7 0.2
357.6 7 0.3
364.9 7 0.1
366.9 7 0.8
378.1 7 0.2
385.5 7 0.4
393.1 7 0.4
400.1 7 0.3
408.9 7 0.6
417 7 1
424.6 7 0.1
433.7 7 0.8
436 7 1
449.9 7 0.1
458.79 7 0.06
466.7 7 0.3
474.9 7 0.4
484.0 7 0.0
492.4 7 0.5
500.1 7 0.3
509.25 7 0.05
517.3 7 0.3
525.4 7 0.6
534.297 0.07
542.9 7 0.4
550.2 7 0.5
559.1 7 0.5
28
S. Stefani et al. / Journal of Quantitative Spectroscopy & Radiative Transfer 117 (2013) 21–28
and the MIR, using the Globar source, KBr beam splitter and
the MCT detector from 800 to 6000 cm 1. Each spectrum
results from the addition of 150 scans acquired with a
resolution of 2 cm 1. In Table A1, the first column represents the altitude with respect to the surface. The errors
reported for pressure and temperature correspond to statistical errors evaluated as standard deviation of the the
pressure and temperature fluctuations during the recording
of the spectra. Absolute errors are 71 1C for temperature
and 70.5% of the full scale for the pressure gauges.
[4]
[5]
[6]
[7]
References
[8]
[1] Rothman LS, Gordon IE, Barbe A, Benner DC, Bernath PE, Birk M, et al.
The HITRAN 2008 molecular spectroscopic database. J Quant Spectrosc
Radiat Transfer 2009;110:533–72. http://dx.doi.org/10.1016/j.jqsrt.
2009.02.013.
[2] Rothman LS, Gordon IE, Barber RJ, Dothe H, Gamache RR, Goldman
A, et al. HITEMP, the high-temperature molecular spectroscopic
database. J Quant Spectrosc Radiat Transfer 2010;111:2139–50.
http://dx.doi.org/10.1016/j.jqsrt.2010.05.001.
[3] Tashkun SA, Perevalov VI, Teffo JL. CDSD-296, the high-precision
carbon dioxide spectroscopic databank: version for atmospheric
applications. In: Perrin A, SariZizi NB, Demaison J, editors. Remote
sensing of the atmosphere for environmental security. Nato Science
for Peace and Security Series C—Environmental Security; NATO.
NATO Advanced Research Workshop on Remote Sensing of the
Atmosphere for Environmental Security, Rabat, MOROCCO,
[9]
[10]
[11]
[12]
November 16–19, 2005; 2006. p. 161–9, http://dx.doi.org/10.
1007/978-1-4020-5090-9_10. ISBN: 1-4020-5088-7.
Piccioni G, Drossart P, Suetta E, Cosi M, Amannito E, Barbis A, et al.,
editors. VIRTIS: the visible and infrared thermal imaging spectrometer; ESA special publication, vol. 1295; 2007.
Tran H, Boulet C, Stefani S, Snels M, Piccioni G. Measurements and
modeling of high pressure pure CO2 spectra from 750 to 8500 cm 1.
I—central and wing regions of the allowed vibrational bands. J Quant
Spectrosc Radiat Transfer 2011;112:925–36. http://dx.doi.org/10.
1016/j.jqsrt.2010.11.021.
Frommhold L. Collision-induced absorption in gases; 1994.
Richard C, Gordon IE, Rothman LS, Abel M, Frommhold L, Gustafsson M,
et al. New section of the HITRAN database: collision-induced absorption (CIA). J Quant Spectrosc Radiat Transfer 2012;113(11):
1276–85. http://dx.doi.org/10.1016/j.jqsrt.2011.11.004.
Seiff A, Schofield JT, Kliore AJ, Taylor FW, Limaye SS, Revercomb HE,
Sromovsky LA, Kerzhanovich VV, Moroz VI, Marov MY. Models of
the structure of the atmosphere of Venus from the surface to 100
kilometers altitude. Adv Space Res 1985;5:3–58.
Schurin BD, Ellis RE. Integrated intensity measurements of carbon
dioxide in the 20 mm, 1:6 mm and 1:43 mm regions. Appl Opt
1968;7:467–70. http://dx.doi.org/10.1364/AO.7.000467.
Lemmon E, McLinden M, Friend D. Thermophysical properties of
fluid systems. NIST chemistry webbook, NIST standard reference
database; 2005. p. 69.
Baranov Y, Vigasin A. Collision-induced absorption by CO2 in the region
of n1 , 2n2 . J Mol Spectrosc 1999;193:319–25. http://dx.doi.org/10.
1006/jmsp.1998.7743.
Vigasin A. Intensity and bandshapes of collision-induced absorption by CO2 in the region of the Fermi doublet. J Mol Spectrosc
2000;200:89–95. http://dx.doi.org/10.1006/jmsp.1999.8022.