The rotation-torsion spectrum of CD2HOH Coudert, L.H.; Motiyenko, R.A.; Margulès, L. ...
Journal of molecular spectroscopy,
09/2021, Volume:
381
Journal Article
Peer reviewed
Open access
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•72 torsional subbands assigned in CD2HOH.•Parallel & perp. transitions available up to K = 12 and vt = 2.•5911 transitions analyzed with a rotation-torsion Hamiltonian.
New ...transitions are reported in the submillimeter wave, terahertz, and far-infrared rotation-torsion spectrum of doubly-deuterated methanol CD2HOH. The newly assigned transitions allow us to spectroscopically characterize torsional states with 0⩽K⩽12 and 0⩽vt⩽2. Three line position analyses are carried out. In the first one, restricted to rotation-torsion lines involving torsional states with 3⩽K⩽12 and vt⩽2, rotational energies are evaluated with a J(J+1) Taylor-type expansion for each torsional state. 4853transitions were accounted for with a unitless standard deviation of 11.4. In the second analysis, 126torsional subband centers are fitted to obtain refined torsional parameters including the hindering potential. In the third analysis, 5911rotation-torsion transitions involving torsional states with vt⩽2, and J⩽26 are reproduced with a unitless standard deviation of 3.2 using a four-dimensional rotation-torsion fitting Hamiltonian.
•Absolute line intensities for the ν4 bands of Trans-HONO and Cis-HONO measured.•Improved line positions using infrared FTS spectra on SOLEIL.•Line list for HONO in the 11 µm infrared region.•For ...cis-HONO, the {41, 51, 61} energy levels are coupled together.
The goal of this work was to update and significantly improve the line lists that have been generated recently for 11 µm bands of the trans- and cis- conformer forms of nitrous acid (HONO) Armante R, Perrin A, Kwabia Tchana F, Manceron L. The ν4 bands at 11 μm: linelists for the trans- and cis- conformer forms of nitrous acid (HONO) in the 2019 version of the GEISA database. Molecular Physics 2021;120:e1951860. That 2019 version of the 11 µm line list was generated using the spectroscopic parameters that were available, at that time, in the literature. During the present study, we used high-resolution Fourier transform spectra recorded at 11 µm to perform a large investigation of line positions and intensities for the ν4 bands of the trans- and cis-conformer of HONO. The resulting set of experimental ν4 (absolute) intensities and of 41 energy levels were used to determine, by least squares fit computations, improved position and intensity parameters for the ν4 bands of the trans- and cis-conformer of HONO. For trans-HONO, the ν4 band appeared not to be perturbed, while for cis-HONO a weak high order B-type Coriolis, coupling together the 41 and 61 energy levels was evidenced for the first time. This new list is of potential interest for the IASI-NG (Infrared Atmospheric Sounding Interferometer - New Generation) instrument which will be launched on board the METOP-SG satellite in 2025.
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•GEISA-2020 database release: 6,746,987 entries in the line parameters database.•23 molecules updated and 6 new molecules added (HONO, COFCl, CH3F, CH3I, RuO4, H2C3H2 (isomer of ...C3H4).•Evaluation of the spectroscopic parameters through radiative transfer simulations compared to atmospheric spectra (SPARTE chain).
This paper describes the 2020 release of the GEISA database (Gestion et Etude des Informations Spectroscopiques Atmosphériques: Management and Study of Atmospheric Spectroscopic Information), developed and maintained at LMD since 1974. GEISA is the reference database for several current or planned Thermal and Short-Wave InfraRed (TIR and SWIR) space missions IASI (Infrared Atmospheric Sounding Interferometer), IASI-NG (IASI New Generation), MicroCarb (Carbon Dioxide Monitoring Mission), Merlin (MEthane Remote sensing LIdar missioN). It is actually a compilation of three databases: the “line parameters database”, the “cross-section sub-database” and the “microphysical and optical properties of atmospheric aerosols sub-database”. The new edition concerns only the line parameters dataset, with significant updates and additions implemented using the best available spectroscopic data.
The GEISA-2020 line parameters database involves 58 molecules (145 isotopic species) and contains 6,746,987 entries, in the spectral range from 10−6 to 35877 cm−1. In this version, 23 molecules have been updated (with 10 new isotopic species) and 6 new molecules have been added (HONO, COFCl, CH3F, CH3I, RuO4, H2C3H2 (isomer of C3H4)) corresponding to 15 isotopic species. The compilation can be accessed through the AERIS data and services center for the atmosphere website (https://geisa.aeris-data.fr/), with the development of a powerful graphical tool and convenient searching, filtering, and plotting of data using modern technologies (PostgreSQL database, REST API, VueJS, Plotly).
Based on four examples (H2O, O3, O2 and SF6), this paper also shows how the LMD in house validation algorithm SPARTE (Spectroscopic Parameters And Radiative Transfer Evaluation) helps to evaluate, correct, reject or defer the input of new spectroscopic data into GEISA and this, thanks to iterations with researchers from different communities (spectroscopy, radiative transfer).
This paper is the first of two back-to-back works, whose goal is to update the existing line positions and intensities spectroscopic parameters for the 5.8 µm region of nitric acid in the HITRAN or ...GEISA spectroscopic databases. This first study is devoted to the generation of first linelists for the ν
2
+ν
9
-ν
9
, ν
2
+ν
7
-ν
7
and ν
2
+ν
6
-ν
6
hot bands in the 5.8 µm region, whereas the second study will concern the positions and intensities for the ν
2
band centred at 1709.567 cm
−1
. High-resolution Fourier transform spectra were recorded in the 5.8 µm and in the 4.2-4.6 µm spectral ranges. The identification of the ν
2
+ν
9
, ν
2
+ν
7
and ν
2
+ν
6
bands of HNO
3
at 2165.0036, 2285.9657 and 2351.216 cm
−1
, respectively, was performed, and several assignments were confirmed by searching for ν
2
+ν
9
-ν
9
and ν
2
+ν
7
-ν
7
transitions within those of ν
2
at 5.8 µm. Both ν
2
+ν
6
and ν
2
+ν
9
bands are highly perturbed. Surprisingly, both ν
2
+ν
9
and ν
2
+ν
9
-ν
9
bands exhibit large amplitude torsional splittings of ∼0.043 cm
−1
. This is presumed to be due to the existence of an anharmonic resonance that couples together the 2
1
9
1
energy levels with those of a dark state involving high excitation in the ν
9
large amplitude OH torsional mode.
Context. Dimethyl sulfide, CH3SCH3 (DMS), is a nonrigid, sulfur-containing molecule whose astronomical detection is considered to be possible in the interstellar medium. Very accurate spectroscopic ...constants were obtained by a laboratory analysis of rotational microwave and millimeter wave spectra, as well as rotation-torsional far-infrared (FIR) spectra, which can be used to predict transition frequencies for a detection in interstellar sources. Aims. This work aims at the experimental study and theoretical analysis of the ground torsional state and ground torsional band ν15 of DMS in a large spectral range for astrophysical use. Methods. The microwave spectrum was measured in the frequency range 2−40 GHz using two Molecular Beam Fourier Transform MicroWave (MB-FTMW) spectrometers in Aachen, Germany. The millimeter spectrum was recorded in the 50−110 GHz range. The FIR spectrum was measured for the first time at high resolution using the FT spectrometer and the newly built cryogenic cell at the French synchrotron SOLEIL. Results. DMS has two equivalent methyl internal rotors with a barrier height of about 730 cm-1. We performed a fit, using the XIAM and BELGI-Cs-2Tops codes, that contained the new measurements and previous transitions reported in the literature for the ground torsional state νt = 0 (including the four torsional species AA, AE, EA and EE) and for the ground torsional band ν15 = 1 ← 0 (including only the AA species). In the microwave region, we analyzed 584 transitions with J ≤ 30 of the ground torsional state νt = 0 and 18 transitions with J ≤ 5 of the first excited torsional state νt = 1. In the FIR range, 578 transitions belonging to the torsional band ν15 = 1 ← 0 with J ≤ 27 were assigned. Totally, 1180 transitions were included in a global fit with 21 accurately determined parameters. These parameters can be used to produce a reliable line-list for an astrophysical detection of DMS.
This paper is the second of two back-to-back works, whose goal was to generate a more accurate linelist for the 5.8 µm absorption band of HNO
3
. Here, we report improved line positions and ...intensities in the ν
2
cold band which is the main band in this region. For this, we recorded four high-resolution Fourier transform spectra for the ν
2
band, centered at 1709.567 cm
−1
, under different experimental conditions. Using these spectra, a new extended line position analysis was performed for the ν
2
band, leading to more accurate line positions. In parallel, individual line intensities were measured. It appears that, although the ν
2
band is mainly of B-type, it also possesses a (very) weak A-type component that cannot be ignored. Overall, the line intensities in this new database are about 8% weaker than those quoted presently in the HITRAN (
https://hitran.org/
) or GEISA (
https://geisa.aeris-data.fr/
) databases. Our final linelist for HNO
3
at 5.8 µm is provided as a supplement to this paper. It includes lines from the ν
2
band together with those of the ν
2
+ν
9
−ν
9,
ν
2
+ν
6
−ν
6
, and ν
2
+ν
7
−ν
7
associated hot bands that were generated during the first part of this study, described in the companion paper.
The 2009 edition of the GEISA spectroscopic database Jacquinet-Husson, N.; Crepeau, L.; Armante, R. ...
Journal of quantitative spectroscopy & radiative transfer,
10/2011, Volume:
112, Issue:
15
Journal Article
Peer reviewed
The updated 2009 edition of the spectroscopic database GEISA (Gestion et Etude des Informations Spectroscopiques Atmosphériques; Management and Study of Atmospheric Spectroscopic Information) is ...described in this paper. GEISA is a computer-accessible system comprising three independent sub-databases devoted, respectively, to: line parameters, infrared and ultraviolet/visible absorption cross-sections, microphysical and optical properties of atmospheric aerosols. In this edition, 50 molecules are involved in the line parameters sub-database, including 111 isotopologues, for a total of 3,807,997 entries, in the spectral range from 10
−6 to 35,877.031
cm
−1.
The successful performances of the new generation of hyperspectral sounders depend ultimately on the accuracy to which the spectroscopic parameters of the optically active atmospheric gases are known, since they constitute an essential input to the forward radiative transfer models that are used to interpret their observations. Currently, GEISA is involved in activities related to the assessment of the capabilities of IASI (Infrared Atmospheric Sounding Interferometer;
http://smsc.cnes.fr/IASI/index.htm) on board the METOP European satellite through the GEISA/IASI database derived from GEISA. Since the Metop-A (
http://www.eumetsat.int) launch (19 October 2006), GEISA is the reference spectroscopic database for the validation of the level-1 IASI data. Also, GEISA is involved in planetary research, i.e., modeling of Titan's atmosphere, in the comparison with observations performed by Voyager, or by ground-based telescopes, and by the instruments on board the Cassini–Huygens mission.
GEISA, continuously developed and maintained at LMD (Laboratoire de Météorologie Dynamique, France) since 1976, is implemented on the IPSL/CNRS (France) “Ether” Products and Services Centre WEB site (
http://ether.ipsl.jussieu.fr), where all archived spectroscopic data can be handled through general and user friendly associated management software facilities. More than 350 researchers are registered for on line use of GEISA.
► Strong interaction with Earth's and planetary atmospheres remote sensing. ► Improvement of the quality of the direct and inverse planetary atmosphere modeling. ► Evident importance for Research in Climate and Environment.► Promotion and motivation for Research in Spectroscopy (theoretical and experimental).
A severe nuclear accident may induce a dramatic dissemination of radioactive species into the environment. In that respect, improving the nuclear safety remains an important challenge to improve the ...society acceptability towards this energy. A solution may consist on implementing robust and reliable measurement systems operating near the Containment Venting Systems (CVS). These devices should be able to provide real time monitoring of the emitted fission products (FPs) in the course of a hypothetical accidental sequence. In the present study, a peculiar attention was devoted to iodine species (namely CH
3
I) measurement by complementary techniques (photoacoustic spectroscopy and gas chromatography). The most important results will be described here.
We present a new global study of the millimeter, submillimeter and far-infrared (FIR) spectra of dimethylsulfide ((CH3)2S). New microwave measurements have been carried out between 49 and 660 GHz ...using spectrometers in IRA NASU (Ukraine), and PhLAM Lille (France). Pure rotational transitions belonging to the three lowest torsional states (ν11,ν15) = (0,0), (1,0), (0,1) of the molecule as well as to intertorsional transitions (ν11,ν15) = (1,0) ↔ (0,1) observable in the millimeter and submillimeter wave ranges due to intensity borrowing via avoided-crossing interactions were combined with new assignments in the fundamental torsional band (AILES beamline of the synchrotron SOLEIL) and analyzed using a model developed for molecules with two equivalent methyl rotors and C2v symmetry at equilibrium (PAM_C2v_2tops program). The upper limit of the frequency range coverage for the microwave data was extended from 300 GHz to 660 GHz and all symmetry species in the torsional excited states and fundamental torsion band of the molecule were analyzed. The final fit included 87 parameters to give an overall weighted root-mean-square deviation of 0.71 for the dataset with J up to 60 consisting of 22277 microwave line frequencies belonging to the three lowest torsional states (ν11,ν15) = (0,0), (1,0), (0,1) as well as to intertorsional transitions (ν11,ν15) = (1,0) ↔ (0,1) and 5720 FIR line frequencies belonging to the observed fundamental band associated with the methyl-top torsion mode (ν11,ν15) = (0,1) ← (0,0). This investigation presents a twofold expansion in the J quantum number for the ground torsional state (ν11,ν15) = (0,0) and the fundamental torsional band (ν11,ν15) = (0,1) ← (0,0); and significantly extends the analysis for the excited torsional states with one torsional quantum excited (ν11,ν15) = (1,0) and (0,1) for which only 18 transitions with J ≤ 5 were analyzed in previous work.
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•A new global study of the mm, submm and FIR spectra of dimethylsulfide.•Analysis of all symmetry species in the fundamental torsional band of dimethylsulfide.•Performance of PAM_C2v_2tops program with respect to a higher ρ value is tested.
Absolute individual line intensities of numerous transitions of the fundamental ν
15
, ν
12
and ν
5
bands of oxirane (ethylene oxide, cyc-C
2
H
4
O) have been measured in the 750-950 cm
−1
region ...using eight high-resolution Fourier transform spectra recorded at 0.002 cm
−1
resolution and various pressures. These line intensities were least-squares fit using a theoretical model which takes into account the vibration-rotation interactions linking the upper state rotational levels and, therefore, accurate rotational expansions of the transition moments of the ν
15
, ν
12
and ν
5
vibrational bands were derived. Using the coefficients obtained in the fitting, a line list has been generated and used to perform comparisons with the present measurements. Also, comparisons with measurements taken at medium-low resolution of the ν
15
/ν
12
/ν
5
system show excellent agreement.
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