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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).

High-resolution Fourier Transform spectra have been recorded at room temperature in the frequency region around 13 µm using a high-resolution Fourier transform spectrometer (Bruker IFS 125-HR). Transitions of both 12CH335Cl and 12CH337Cl isotopologues belonging to the P, Q and R branches of the ν3 and 2ν3-ν3 parallel bands have been analyzed to retrieve self-broadening coefficients using a multispectrum fitting procedure that allowed to fit simultaneously the whole set of the experimental spectra recorded at seven pressures of CH3Cl ranging from 1.02 to 10.24 mbar. Line positions were also derived using a wavenumber calibration performed by the frequencies of OCS transitions. About 2028 lines with 2 ≤ J ≤ 59 and 2 ≤ K ≤ 13 have been studied. The rotational J and K dependencies of the self-broadening coefficients have been clearly observed and modeled using a second-order empirical polynomial. The average accuracy of the line parameters has been estimated to be about 4 and 5% for the ν3 and 2ν3-ν3 bands, respectively. Using the Robert and Bonamy formalism with parabolic and exact trajectory models, these coefficients were calculated, showing the predominance of the dipole-dipole interaction. The J and K rotational dependencies are consistent with the measured data. The predicted values confirm that the use of the exact trajectory model does not improve the predicted linewidths for a molecule with a large dipole moment such as CH3Cl.

International audience; The new nitrogen dioxide (NO 2) linelist in the GEISA database and first identification of the ν 1 +2ν 3-ν 3 band of

Four spectra of normal samples of CH4 in the 4300–4600 cm−1 region were recorded by using a Fourier transform spectrometer in Reims, France at long paths (202 m, 602 m, 1604 m, and 1804 m) and different pressures. Additional spectra of 12CH4 covering the same region were obtained at 80–123 K, and 93 m path length at SOLEIL Synchrotron in Paris for different pressures and were used to measure low-J lines. Line positions and intensities were retrieved by non-linear least-squares curve-fitting procedures and analyzed using effective Hamiltonian and effective dipole transition moment models. A new measured line list contains positions and intensities for 14,151 absorption features. Quantum assignments were made for more than 10,304 transitions of 12CH4, which represent ∼99% of the integrated line intensity observed in this region. Some 1699 hot band transitions for (Dyad – Tetradecad) system were assigned. The resulting list of lines is significantly more accurate than previous empirical compilations. Positions of 8605 cold band transitions for (GS – Octad) system were fitted with an RMS standard deviation of 0.0014 cm−1. The sum of observed intensities between 4300 and 4600 cm−1 fell within 8% of the predicted value from ab initio variational calculations reported in the TheoReTS database ( http://theorets.univ-reims.fr ; http://theorets.tsu.ru ).

In this paper, we report high-resolution measurements of oxygen and nitrogen pressure-broadening coefficients for ro-vibrational transitions in the ν3 and 2ν3-ν3 bands of methyl chloride (CH335Cl and CH337Cl). We present the first high-resolution measurement of oxygen broadening coefficients for the CH3Cl, along with an extensive determination of the nitrogen broadening coefficients in the ν3 band which complements the measurements made by diode laser spectrometer in previous works. For the 2ν3-ν3 band, the oxygen and nitrogen broadening coefficients are measured here for the first time. The results have been obtained by analyzing fourteen spectra with a mono-spectrum non-linear least squares fitting of Voigt profile using data recorded at 295 K at the AILES beamline of the SOLEIL Synchrotron facility using a Bruker IF125HR Fourier transform spectrometer. Broadening coefficients of 1793 and 1732 lines in both bands of both isotopes of CH3Cl for O2 and N2 buffer gases respectively have been retrieved. The rotational dependences of these coefficients have been modeled using an empirical model, which reproduces the measured data with a difference of about 6 %. Using the measured values of O2- and N2-broadenings, we derived the Air-broadening coefficients. Finally, comparisons with previous works are performed.

We performed the systematic measurements of line intensities of ro-vibrational absorption transitions of the ν3 and 2ν3-ν3 parallel bands of 12CH335Cl and 12CH337Cl isotopes. The spectra were recorded in the spectral region between 650 and 800 cm−1 with a high-resolution Fourier transform spectrometer. A mono-spectrum fitting technique was used to fit a series of seven spectra at pressures of CH3Cl ranging from 1.02 to 10.24 mbar to retrieve line intensities of 2385 transitions of the two isotopic species. The measured line intensities are discussed in relation to rotational quantum numbers, and used to derive the square of the transition dipole moments for each line. The analysis of these moments allows us to derive a consistent set of line intensity parameters, such as vibrational transition moments, band intensities as well as Herman-Wallis coefficients for both bands. The results of the ν3 band are in satisfactory agreement with previous works and present databases, but a larger discrepancy (≈ 30%) is observed for the 2ν3-ν3 hot band.

International audience; Synopsis A new spectroscopic setup for sub-K solid state measurements at the open user facility AILES @SOLEIL is described. An example of a measurement of transmission and reflection in the 10 to 600 cm-1 range is presented..

We performed the first systematic measurements of line intensities and pressure broadening coefficients of ro-vibrational absorption transitions of the ν6 perpendicular band of CH335Cl and CH337Cl isotopologues. The spectra were recorded in the spectral region between 920 and 1130 cm−1 with a high-resolution Fourier transform spectrometer. A multi-pressure fitting technique was used to fit a series of seven spectra at pressures of CH3Cl ranging from 1.02 to 10.24 mbar to derive these parameters for about 2132 transitions with 1 ≤ J ≤ 55 and 0 ≤ K ≤ 12. The line intensities were discussed as a function of the rotational quantum numbers, and were used to derive the transition dipole moments squared for each line. The analysis of these moments allows us to derive a consistent set of line intensity parameters such as vibrational transition moments, band intensity as well as Herman-Wallis coefficients. The results were found to be in satisfactory agreement with databases and with low resolution measurements of band intensity. The rotational dependencies of the self-broadening coefficients have been clearly observed and modeled using an empirical polynomial law. The average accuracies have been estimated to be around 4 and 5% for line intensities and self-broadening coefficients respectively.

International audience; Sulfur hexafluoride is a powerful greenhouse gas of industrial origin. Remotesensing detection of this heavy species requires a detailed knowledge of its infrared absorption spectra that features many hot bands at room temperature. It is thus necessary to study many of its rovibrational levels which are implied in such hot band transitions. Based on our previous results reporting global fits of many rovibrational bands [M. Faye at al., J. Quant. Spectrosc. Radiat. Transfer 190, 38-47 (2017)], we present here detailed analyses of three combination bands, namely ν 1 + ν 4 , ν 2 + ν 6 and ν 5 + ν 6. The ν 2 + ν 6 combination band has been already investigated some years ago, but the present analysis represents a strong improvement; the two other bands are analyzed in detail for the first time. The results contribute to improve the simulation of hot bands in the strongly absorbing ν 3 and ν 4 regions and they have been used to update the SHeCaSDa database (http://vamdc.icb.cnrs.fr/PHP/shecasda.php).

Silicon tetrafluoride (SiF4) is a trace component of volcanic gases. However, a better knowledge of spectroscopic parameters is needed for this molecule in order to derive accurate concentrations. This motivated FTIR measurements with high-spectral resolution (0.001 cm − 1 ) and an extensive study of its infrared absorption bands, including the fundamentals and overtone and combinations. We present here a detailed analysis and modeling of the strongly absorbing ν3and ν4 fundamental bands, for the three isotopologues in natural abundance: 28SiF4 (92.23 %), 29SiF4 (4.67 %) and 30SiF4 (3.10 %). It includes a global fit with consistent parameter sets for the ground and excited states. In particular, all existing rotational line data have been included. The 2ν4 band of 28SiF4 could also be analyzed in detail. A first fit of the dipole moment derivative for the ν3 band for 28SiF4 has been performed, along with two independent estimates of the integrated band intensity; the results are consistent with literature values, around 690 km/mol. The isotopic dependence of band centers and Coriolis parameters has also been studied. TFSiCaSDa, a new database of cross sections and calculated lines for the ν3 band of SiF4, has been set up.

Silicon tetrafluoride (Si F 4 ) is a trace component of volcanic gases and is gaining industrial importance. However, a better knowledge of spectroscopic parameters is needed for this molecule in order to derive accurate concentrations. Following a previous reinvestigation of the ν 3 and ν 4 fundamentals (Richard et al. 2021), we have undertaken an extensive high-resolution study of its infrared absorption bands. We present here an update of this study. It features the recording of new far-infrared spectra, taking advantage of synchrotron radiation, and a global fit giving a consistent parameter set for the ground and fundamental states of 28 Si F 4 , now including the v 1 = 1 and v 2 = 1 states, by adding to the global analysis the newly measured ν 2 , ν 1 − ν 4 , and ν 4 − ν 2 bands near 264, 412, and 125 cm−1, respectively. Nearly 20 000 assigned lines pertaining to seven distinct rovibrational bands were fitted with an excellent accuracy (global standard deviation of 0.296). This allows us to obtain an accurate experimental value for the Si − F bond length, r e ( SiF 4 ) = 1 . 5516985 ( 30 ) A. Some new band intensity estimates allow us to update our Si F 4 calculated spectroscopic database.

Sulfur hexafluoride is a greenhouse gas with a long lifetime in the atmosphere and an important tracer for air mass circulation atmospheric models. The IR spectrum of this heavy species, however, features many hot bands at room temperature (at which only 30% of the molecules lie in the ground vibrational state), especially those originating from the lowest, v 6 and v 5 = 1 vibrational states. Using a cryogenic long path cell with variable optical path length and temperatures regulated between 168 and 163 K, coupled to Synchrotron Radiation and a high resolution interferometer, Doppler-limited spectra of the very weak ν 3 + ν 5 band near 1450 cm−1 have been recorded. Low temperature was used to limit the presence of hot bands and simplify the rotational structure. The spectrum has been analyzed thanks to the XTDS software package. Combining with the results obtained previously on the weak difference bands in the far infrared region involving the v 5 = 1 states, we are thus able to use the tensorial model to propose a spectroscopic parameter set for modelling the strong ν 3 + ν 5 - ν 5 hot band. The model constitutes a coherent set of molecular parameters and enable spectral simulation for atmospheric sounding. Test simulations at different temperatures and in nitrogen broadened conditions are presented and compared with new experimental cross section data for the absorption region relevant for atmospheric quantification.

The ν 3 band of the 36 SF 6 isotopologue has been recorded in natural abundance (0.02%) at 153 K-temperature with doppler limited resolution, using a Fourier transform spectrometer. For the first time, the high resolution analysis of this band is performed thanks to the Dijon tensorial formalism model. The effective Hamiltonian parameters are determined and the interest of studying rare SF 6 isotopologues is discussed.

Systematic measurements of self-broadening coefficients for 992 transitions in the ν5 and ν3+ν6 perpendicular bands of CH3I up to the quantum numbers 3 ≤ J ≤ 52 and 0 ≤ K ≤ 12 have been performed for the first time using a mono-spectrum fitting technique utilizing a Voigt profile. Our previous line intensity measurements [Boughdiri, et al., JQSRT 221 (2018) 147-154] are also extended using new spectra recorded at room temperature at five pressures from 1.15 to 9.98 mbar using the Bruker IFS125HR Fourier Transform spectrometer at the AILES beamline of the SOLEIL Synchrotron facility. The measured absolute intensities were used to derive the transition dipole moment squared for each line, the band intensities as well as the Herman–Wallis coefficients. The rotational dependences of the self-broadening coefficients have been clearly observed and modeled. The data were compared with previous works. The results are given as supplementary data table for a possible use in atmospheric and industrial applications.

Sulfuryl fluoride (SO2F2) is of a fundamental interest due to its nearly tetrahedral symmetry, making it, thereby, an intermediate case between spherical and asymmetric-top molecules. It is also a widely-used insecticide and an atmospheric pollutant. A new high-resolution infrared spectrum of the ( ν 9 , ν 7 , ν 3 ) bending triad of SO2F2 in the 550 cm−1 region has been recorded at 165 K with a spectral resolution of 0.00102 cm−1 at the AILES beamline of the SOLEIL Synchrotron. Analysis has been performed in the O ( 3 ) ⊃ T d ⊃ C 2 v group chain using a specific model and programs based on tensorial formalism, group theory and vibrational extrapolation method. This model is adapted to the case of XY2Z2 asymmetric-top molecules with C 2 v symmetry developed by Rotger et al. (2002). This approach enables studying any rovibrational band or polyad with a systematic development of all rovibrational interactions. A total of 6058 IR lines has been assigned and fitted in position with a global root mean square deviation (RMS) of 0.484 × 10−3 cm−1. This result improves the previous analyses performed by Burger et al. (2002) and Rotger et al. (2006).

A Fourier transform spectrum of phosgene (Cl2CO) has been recorded in the 11.8 μm spectral region at low temperature and at a resolution of 0.00102 cm−1 using a Bruker IFS125HR spectrometer coupled to synchrotron radiation leading to the observation of the ν5 vibrational band of the isotopologue 37Cl2CO. The corresponding upper state rovibrational levels were fit using a Watson-type Hamiltonian. In this way it was possible to reproduce the upper state rovibrational levels almost to within the experimental uncertainty i.e. ∼0.50 × 10−3 cm−1. Very accurate rotational and centrifugal distortion constants were derived from the fit together with the following band center: ν0 (ν5, 37Cl2CO) = 848.970769 (20) cm−1.

In this study we report the high-resolution measurements of oxygen pressure- broadening and pressure-induced shift coefficients for rovibrational transitions in the ν6 band of methyl iodide (12CH3I), centered at 892.918 cm–1. The results were obtained by analyzing fourteen high-resolution room temperature laboratory absorption spectra with a mono-spectrum non-linear least squares fitting of Voigt profiles. The data were recorded with the Bruker IF125HR Fourier transform spectrometer located at the LISA facility in Créteil, using a White type cell with a path length of 564.9 cm and total pressures up to 295 hPa. The measured oxygen-broadening coefficients range from 0.0648 to 0.1207 cm–1atm–1 at 295 K. The measured shift coefficients were all negative and varied between −0.00044 and −0.04984 cm–1atm–1. The average accuracy on the measured O2-broadening coefficients and pressure shift coefficients was estimated to about 4% and 11%, respectively. The O2-broadening coefficients obtained in the present work are compared with values reported in the literature for the ν5 band of CH3I, showing a satisfactory agreement with an average difference of about 8%. The shift coefficients are compared with values reported in the literature for the ν6 band of CH3F-Ar system, exhibiting the same order of magnitude and trend. The J and K rotational dependences of the O2-broadening coefficients have been observed and the latter modeled using empirical polynomial expansions. On average, the empirical expression reproduces the measured O2-broadening coefficients to within 3%. Using the measured broadening coefficients of the CH3I-O2 and CH3I-N2 [Attafi et al. J Quant Spectrosc Radiat Transf 231 (2019) 1–8] systems, we produced CH3I-air broadening coefficients, ranging from 0.0783 to 0.1385 cm–1atm–1 at 295 K. The present results and the data already available should be valuable not only for predicting the CH3I infrared spectrum in the atmosphere, but also for verifying theoretical calculations of pressure-broadening and pressure-shift coefficients in the ν6 region of methyl iodide spectra., SCOPUS: ar.j, info:eu-repo/semantics/published

Following our recent study devoted to measurements of intensities of rovibrational lines in the ν6 band of methyl iodide (12CH3I) centered at 892.918 cm−1, room temperature infrared spectra of methyl iodide diluted in nitrogen at fourteen total pressures between 20 and 300 hPa have been recorded using the Fourier transform spectrometer Bruker IF125HR located at the LISA facility in Creteil. Three hundred and forty six N2-broadening coefficients of methyl iodide rovibrational lines have been measured in the 824–951 cm−1 spectral range using mono-spectrum non-linear least squares fitting of Voigt profiles. Pressure-induced line shifts were not needed to fit the spectra to the noise level and line mixing effects could be neglected. Six hundred and eight self-broadening coefficients have also been measured in the same spectral range using the pure methyl iodide spectra recorded in our previous work. The measured self-broadening coefficients range from 0.1460 to 0.3786 cm−1 atm−1 and the N2-broadening coefficients range from 0.0723 to 0.1481 cm−1 atm−1 at 295 K. The average accuracy on the measured self- and N2-broadening coefficients was estimated to 3%. Comparisons with measurements reported in the literature for the ν5 band of CH3I shows a satisfactory agreement with average differences of 7% and 4% for the self- and N2-broadening coefficients, respectively. The J and K rotational dependences of these coefficients have been observed and the latter modeled using an empirical polynomial expansion. On average, the empirical expression reproduces the measured self- and N2-broadening coefficients to within 3% and 4%, respectively. The data obtained in the present work represent a significant contribution to the determination of broadening coefficients of CH3I and complement the list of line positions and intensities generated in our previous work, thus providing useful spectroscopic information for atmospheric remote sensing and industrial detection of CH3I.

New experimental high-resolution Fourier-Tansform infrared spectra of the infrared active fundamental ν2 band of sulfuryl fluoride SO2F2, have been recorded at a temperature of 193 K and at resolution of 0.00102 cm − 1 at the AILES (Advanced Infrared Line Exploited for Spectroscopy) beamline of the SOLEIL (Source Optimisee de Lumiere d’Energie intermediaire du LURE) Synchrotron facility. A detailed analysis has been performed both in line positions and intensities with the C2vTDS (Top Data System) program suite, based on the tensorial formalism developed in Dijon for quasi-spherical top molecules. The effective Hamiltonian was developed up to fourth order. The parameter of the effective dipole moment operator has been determined using the wavefunctions of the effective Hamiltonian operator. 2407 line positions have been measured with global root mean square deviation of about 0.19 × 10 − 3 cm − 1 . Using 71 lines intensities, we estimate the uncertainty on calculated line intensities to 10%. To the extent of our knowledge, this is the first time that an absolute intensity analysis has been carried out for sulfuryl fluoride.

Eight spectra of normal samples of CH4 in the 3760–4100 cm−1 region were recorded by using a Fourier transform spectrometer in Reims, France at long paths (202 m, 602 m, 1604 m and 1804 m) and different pressures. Additional spectra of 12CH4 covering the same region were obtained at 100 K and very low sample pressures, which was used for low-J line position identification. Line positions and intensities were retrieved by least squares curve-fitting procedures and analyzed using the effective Hamiltonian and the effective dipole. A new measured line list contains positions and intensities for 9000 features. Quantum assignments were made for more than 3500 new transitions, which represent ∼95% of the integrated line intensity observed in this region. The resulting list of lines is much more accurate than the list of lines HITRAN 2016. All assigned 5703 line positions were fitted to RMS standard deviations of 0.0018 cm−1. The sum of observed intensities between 3760 and 4100 cm−1 fell within 2% of the predicted value from ab initio variational calculations reported in the TheoReTS database ( http://theorets.univ-reims.fr ; http://theorets.tsu.ru ).

The 12.6 µm region of nitryl chloride (ClNO2) has been recorded at high resolution (0.00102 cm−1) using a Fourier transform spectrometer and the SOLEIL synchrotron light source. ClNO2 was found during our studies of chlorine nitrate and, after fractional distillations it was introduced into a multipass White cell made of inert materials, with an optical path length of 5.4 m. 320 scans were recorded for the range 600–980 cm−1 at a total pressure of 0.23 hPa and a temperature of 250 K. A thorough analysis of the ν2, 2ν6 and 2ν3 bands of 35ClNO2 and of the ν2 band of 37ClNO2 falling in this region has been carried out using a Hamiltonian model which takes explicitly into account the numerous resonances affecting the ro-vibrational energy levels; especially the C-type Coriolis resonance between the ν2 and the ν3 + ν6 modes. These two modes are only separated by less than 20 cm−1 and are thoroughly mixed. From the fittings, the following band centers were derived: νo(ν2) = 792.761264(60) cm−1, νo(ν3 + ν6) = 775.8923(20) cm−1, νo(2ν3) = 734.183576(20) cm−1 and νo(2ν6) = 819.836727(90) cm−1 for 35ClNO2 and νo(ν2) = 792.258284(30) cm−1 and νo(ν3 + ν6) = 774.6826(30) cm−1 for 37ClNO2 where the uncertainties are one standard deviation. Due to their sharp Q branches falling into an atmospheric “window”, the detection of the ν2 bands might be an advantageous route for future attempts to quantify atmospheric ClNO2, using infrared techniques.

The high‐resolution infrared absorption spectrum of the donor bending fundamental band ν 61 of the homodimer (HCN)2 has been collected by long‐path static gas‐phase Fourier transform spectroscopy at 207 K employing the highly brilliant 2.75 GeV electron storage ring source at Synchrotron SOLEIL. The rovibrational structure of the ν 61 transition has the typical appearance of a perpendicular type band associated with a Σ–Π transition for a linear polyatomic molecule. The total number of 100 assigned transitions are fitted employing a standard semi‐rigid linear molecule Hamiltonian, providing the band origin ν 0 of 779.05182(50) cm−1 together with spectroscopic parameters for the degenerate excited state. This band origin, blue‐shifted by 67.15 cm−1 relative to the HCN monomer, provides the final significant contribution to the change of intra‐molecular vibrational zero‐point energy upon HCN dimerization. The combination with the vibrational zero‐point energy contribution determined recently for the class of large‐amplitude inter‐molecular fundamental transitions then enables a complete determination of the total change of vibrational zero‐point energy of 3.35±0.30 kJ mol−1. The new spectroscopic findings together with previously reported benchmark CCSDT(Q)/CBS electronic energies [Hoobler et al. ChemPhysChem. 19, 3257–3265 (2018)] provide the best semi‐experimental estimate of 16.48±0.30 kJ mol−1 for the dissociation energy D 0 of this prototypical homodimer., The rotationally resolved infrared spectrum of the hydrogen bond donor bending fundamental transition ν61 of (HCN)2 has been observed by long‐path static gas‐phase Fourier transform spectroscopy at 207 K employing the highly brilliant 2.75 GeV electron storage ring source at Synchrotron SOLEIL.

N2- and O2-broadening coefficients were measured at room temperature for 2914 ro-vibrational lines of methyl chloride in the region from 920 to 1140 cm−1 corresponding to the ν6 band, using a high-resolution Fourier transform spectrometer and a mono-spectrum non-linear least squares fitting of Voigt profiles. The spectra were recorded at the AILES beamline of the SOLEIL Synchrotron facility at various mixtures of CH3Cl with N2 or O2 gas. Broadening coefficients were retrieved for the two isotopes of CH3Cl from which we derived the air-broadenings. The rotational dependences of these coefficients were analyzed and modeled first using an empirical model, which reproduces the measurements within of about 5%. Pressure - induced shifts are also measured for about 375 and 418 transitions for O2- and N2-perturbers respectively with no obvious rotational dependence. The average absolute accuracies of the measurements are estimated to be about 7 and 17% for broadening and shift coefficients respectively. Comparisons are performed with previous measurements and next with semi-classical predictions achieved in this work. The entire set of results is given as Supplementary data Table for a use in spectroscopic databases and atmospheric detection.

Extensive measurements of line positions and intensities are reported for the inversion-rotation and rovibrational transitions of 14NH3 in the 50–660 cm−1 region. This study analyzes high-resolution (0.00167 cm−1, unapodized) Fourier-transform spectra of high purity (99.5%) normal ammonia sample obtained using the AILES beamline of Synchrotron SOLEIL. The experimental conditions are designed to study transitions with intensities weaker than 1 × 10−22 cm−1/(molecule cm−2) at room temperature. Line positions and intensities of more than 2830 transitions of 14NH3 are measured and compiled after proper quality control; the features from minor isotopologues (15NH3 and NH2D) and H2O are identified and excluded. Based on the predictions of recent work from the empirical Hamiltonian modeling, systematic quantum assignments are made for 2047 transitions from eight bands including four inversion-rotation (gs, v2, 2v2, and v4) and four ro-vibrational bands (v2–gs, 2v2–v2, v4–v2, and 2v2–v4), as well as covering their ΔK = 3 forbidden transitions. The measured line positions for the assigned transitions are in an excellent agreement (typically better than 0.001 cm−1) with the predictions in a wide range of J and K for all the eight bands. The comparison with the HITRAN 2012 database is also satisfactory, although systematic offsets are seen for transitions with high J and K and those from weak bands. Also we note that out of the eight bands, the 2v2–v4 has not been listed in the HITRAN 2012 database. Differences of 20% are seen between our measured and calculated intensities depending on the bands. For line positions, greater differences are found for some NH3 bands in HITRAN 2012 than recent predictions. Measurements of the individual line positions and intensities are presented for the eight bands, and the final spectroscopic line positions and intensities are compiled as an electronic supplement.

The high-resolution absorption spectra of phosgene (Cl 2 CO) has been recorded at 0.001 cm −1 resolution in the 250–350 cm −1 region by Fourier transform spectroscopy at synchrotron SOLEIL. To reduce the spectral congestion, the spectra have been recorded at low temperature (197 K) using a 93.14 m optical path length cryogenic cell. This enables the first detailed infrared analysis of the ν 3 bands of the 35 Cl 2 CO and 35 Cl 37 ClCO isotopologues of phosgene. Using a Watson-type Hamiltonian, it was possible to reproduce the upper state rovibrational infrared energy levels, together with, for 35 Cl 2 CO, the available microwave data in the 3 1 excited state (Yamamoto et al. 1984) to within their experimental accuracy. In this way, accurate rotational and centrifugal distortion constants together with the following band centers: ν 0 ( ν 3 , 35 Cl 2 CO) = 301.545622(17) cm −1 and ν 0 ( ν 3 , 35 Cl 37 ClCO) = 298.199194(81) cm −1 , were derived for the ν 3 bands of 35 Cl 2 CO and 35 Cl 37 ClCO.

The torsional and rotation–torsion spectra of the doubly deuterated species of methanol CD2HOH have been analyzed using submillimeter wave, terahertz, and far infrared spectra. 101 torsional subbands, with subband centers ranging from 2.3 to 626 cm−1, were assigned. Analysis of these yielded kinetic energy and hindering potential parameters of the torsional Hamiltonian describing the large amplitude internal rotation of the CD2H methyl group with respect to the hydroxyl group. 3271 rotation and rotation–torsion transitions, involving the 24 torsional levels up to e 1 with 3 ⩽ K ⩽ 10 , were assigned and fitted approximating the rotational energy of each torsional level with a Taylor-type expansion in J ( J + 1 ) . The rotational structure of 48 torsional subbands involving torsional levels higher than e 1 has also been analyzed. In most cases, only the Q branch could be observed and assigned.

A new high-resolution infrared spectrum of the ν 2 band of SO2F2 centered at 849.46 cm−1 has been recorded with a resolution of 0.00102 cm−1 at the AILES beamline of SOLEIL Synchrotron facility. More than 1600 lines up to Jmax = 41 have been assigned and fitted in line position using a tensorial formalism adapted to the case of XY2Z2 asymmetric molecules developed as an extension of the usual one used for spherical tops (Rotger et al., 2002). The analysis has been performed in the O ( 3 ) ⊃ T d ⊃ C 2 v group chain, thanks to the C2vTDS program suite (Wenger et al., 2005). This approach allows a systematic development of rovibrational interaction to study any polyad of SO2F2 and makes easier global analysis. Compared to a previous study (Merke et al., 2006), the present fit uses less effective Hamiltonian parameters but we assigned lines up to a lower J value.

In this paper, we present the high resolution analysis of the weak ν 2 + ν 4 - ν 5 band of SF6 around 735 cm−1. The spectra were recorded on the AILES Beamline at the SOLEIL Synchrotron facility using a cryogenic multipass cell coupled to a Bruker 125HR spectrometer with a maximum resolution of 0.00102 cm−1. For this band, we worked with 4 mbar of SF6 at a temperature of 223 ± 2 K. The optical path length was fixed to 141 m and the spectrum recorded with 0.001 cm−1 of resolution. A new, cold spectrum of the ν 2 + ν 4 band was also collected at 153 K, 15-m path length, and 0.0015 cm−1 resolution. The analysis was performed by using the Dijon group XTDS and SPVIEW software, based on tensorial formalism. We achieved correct simulation and line position assignments of the ν 2 + ν 4 - ν 5 band, by gathering ν 2 + ν 4 data and ν 5 Raman data. We could assign 3553 transition for ν 2 + ν 4 - ν 5 with a standard deviation of 1.292 × 10 - 3 cm−1. This analysis also helped improve the v2 = v4 = 1 level and the v5 = 1 fundamental level v2 = v4 = 1.

International audience; A new investigation of the ν3 bands of 35ClNO2 and 37 ClNO2, located around 370 cm−1 has been performed using a high resolution (0.00102 cm−1) Fourier transform spectrum recorded at SOLEIL with highly improved experimental conditions as compared to previous work [Orphal J, Morillon-Chapey M, Klee S, Mellau GC, Winnewisser M. J Mol Spectrosc 1998;190:101–6]: (i) the use of synchrotron radiation which resulted in a better signal-to-noise ratio; (ii) a resolution twice better; (iii) a low temperature (221 K) with an optical path length of 8.16 m, allowing low pressure (0.025 hPa) in the sample leading to a well resolved spectrum. As a consequence, significantly better results than previously were obtained. Thanks to the new experimental conditions, the line assignments were pursued up to higher J and Ka quantum number values, J = 83 and Ka = 44. For both isotopomers, a total of 6331 transitions were reproduced with a root-mean-square deviation of 2 × 10−4 cm−1 using a Watson-type A-reduced Hamiltonian. Improved rotational and centrifugal distortion constants for the ν3 fundamental bands of 35ClNO2 and 37 ClNO2 have been determined. The band centers are 370.1510773(92) cm−1 for the ν3 fundamental band of 35ClNO2 and 364.5218094(96) cm−1 for the ν3 fundamental band of 37ClNO2. The synthetic line list obtained in this study could be interesting for future measurements of ClNO2 in the atmosphere, e.g. using the new space mission FORUM which is one of the concepts chosen by ESA to be developed further and which opens up a new window (150–1400 cm−1 ) for understanding and quantifying the radiative processes, as well as air quality and pollution effects

The germane molecule, GeH4, is present in the atmospheres of giant planets Jupiter and Saturn. The ongoing NASA mission Juno has renewed interest in its spectroscopy, whose accurate modeling is essential for the retrieval of other tropospheric species. We present here the first complete analysis and modeling of line positions and intensities in the strongly absorbing ν1/ν3 stretching dyad region near 2100 cm − 1 , for all five germane isotopologues in natural abundance. New infrared spectra were recorded, absolute intensities were extracted through a careful procedure and modeled thanks to the formalism and programs developed in the Dijon group. A database of calculated germane lines, GeCaSDa, has been build and is available online through the Virtual Atomic and Molecular Data Centre (VAMDC) portal and at http://vamdc.icb.cnrs.fr/PHP/gecasda.php .

International audience; The line intensities for RR- and PP- sub-branch transitions in the ν5 and ν3 + v6 bands of CH3I are measured for the first time for 270 lines with 5 ≤ J ≤ 40 and 4 ≤ K ≤ 11 using a multi-pressure fitting method with a Voigt profile. Seven spectra have been recorded using the Bruker IFS125HR Fourier Transform Spectrometer at the AILES beamline of SOLEIL Synchrotron with a resolution of 0.002 cm-1 for pressures between 0.270 and 2.433 mbar. Line intensities are analyzed and discussed as a function of the rotational quantum numbers. On average, the accuracy of the measured data is estimated to be about 4.5% for the two bands. The measured line intensities have been used to derive the vibrational transition moment, the Herman-Wallis parameters as well as the intensities of the two bands. The values for the band strengths of the ν5 and ν3 + v6are respectively 46.47 ± 2.63 cm-2 atm-1 and 14.79 ± 1.60 cm-2 atm-1. The measured line intensities were reproduced with mean values of difference of about 8.3% and 3.8% for the ν5 and ν3 + v6 bands respectively. At pressure used in this work, analysis of the overlapped line using the Rosenkranz profile demonstrates a negligible line-mixing effect on line intensities.

We report on the characteristics of coherent synchrotron radiation (CSR) as a source for spectroscopy. The optimization of the source and the resulting figures of merits in terms of flux, signal to noise, spatial distribution and spectral and temporal distribution are presented together with a spectroscopic application. The emission of THz during the slicing operation is also described. The conclusion opens up perspectives made possible by the availability of this intense and stable THz source.

RuO 4 is a heavy tetrahedral molecule which has practical uses for several industrial fields. Due to its chemical toxicity and the radiological impact of its 103 and 106 isotopologues, the possible remote sensing of this compound in the atmosphere has renewed interest in its spectroscopic properties. New, higher resolution FTIR spectra have been recorded at room temperature, using an isotopic pure sample of 102 RuO 4 and a sample with all stable isotopes present in natural abundance. We reinvestigate here the strong ν 3 stretching fundamental region and perform new assignments and effective Hamiltonian parameter fits for the five main isotopologues ( 99 RuO 4 , 100 RuO 4 , 101 RuO 4 , 102 RuO 4 and 104 RuO 4 ), by considering the ν 3 stretching mode as an isolated band. We provide precise effective Hamiltonian parameters, including band centers and Coriolis interaction parameters. We discuss isotopic shifts and estimate the band centers for the two minor isotopologues ( 97 RuO 4 and 98 RuO 4 ) and the two radioactive isotopologues ( 103 RuO 4 and 106 RuO 4 ). Experimental band strengths for the two IR active fundamentals are also reported for the first time.

The high-resolution absorption spectrum of trifluoromethyliodide (CF3I), an alternative gas to chlorofluorocarbons but with potential greenhouse effects, has been recorded at 0.001 cm−1 resolution in the 200–350 cm−1 region with the Bruker IFS125HR Fourier transform spectrometer at synchrotron SOLEIL. Due to the spectral congestion and the presence of numerous hot bands, the spectra have been recorded at the AILES Beamline facility at SOLEIL either at room temperature using a 150 m optical path length cell or at 163 K using the new LISA-SOLEIL cryogenic cell and at the Australian synchrotron using a flow cooling cell. This enables a detailed analysis of the v3 band at 286.29712(3) cm−1 of CF3I. The results of previous microwave measurements in the v3 = 1 and v6 = 1 vibrational states (Walters and Whiffen, 1983; Wahi, 1987) were combined with those of the present infrared analysis of the v3 band to obtain an improved set of parameters for the v3 = 1 (C–I stretching) and v6 = 1 (I–C–F bending) interacting vibrational states accounting for the Coriolis resonance coupling the v3 = 1 energy levels with those of the dark v6 = 1 state (located at ∼261.5 or at ∼267.6 cm−1). Finally, a first investigation of the 2v3 − v3 hot band is also performed.

A high resolution (0.0015 cm −1 ) IR spectrum of propane, C 3 H 8 , has been recorded with synchrotron radiation at the French light source facility at SOLEIL coupled to a Bruker IFS-125 Fourier transform spectrometer. A preliminary analysis of the ν 21 fundamental band (B 1 , CH 3 rock) at 921.382 cm −1 reveals that the rotational energy levels of 21 1 are split by interactions with the internal rotations of the methyl groups. The AA, EE and AE + EA components of this A-type band have their band centers at 921.3724(38), 921.3821(33) and 921.3913(44) cm −1 , respectively. These torsional splittings most probably are due to anharmonic and/or Coriolis resonance couplings with nearby highly excited states of both internal rotations of the methyl groups. In addition, several vibrational–rotational resonances were observed that affect the torsional components in different ways.

International audience; RuO 4 is a heavy tetrahedral molecule of interest in several fields. Due to its chemical toxicity and radiological impact of its 103 and 106 isotopologues, the possible remote sensing of this compound in the atmosphere has renewed interest in its spectroscopic properties. We investigate here, for the first time at high resolution, the bending modes region in the far infrared. High resolution FTIR spectra have been recorded near room temperature, using a specially designed cell and an isotopically pure sample of 102 RuO 4. New assignments and effective Hamiltonian parameter fits for the main isotopologue (102 RuO 4) have been performed, treating the whole ν 2 /ν 4 bending mode dyad. We provide precise effective Hamiltonian parameters, including band centers and Coriolis interaction parameters.

Sulfur hexafluoride is an important prototypal molecule for modeling highly excited vibrational energy flow and multi quanta absorption processes in hexafluoride molecules of technological importance. It is also a strong greenhouse gas of anthropogenic origin. This heavy species, however, features many hot bands at room temperature (at which only 30% of the molecules lie in the ground vibrational state), especially those originating from the lowest, v 6 =1 vibrational state. Using a cryogenic long path cell with variable optical path length and temperatures regulated between 120 and 163 K, coupled to Synchrotron Radiation and a high resolution interferometer, Doppler-limited spectra of the 2 ν 1 + ν 3 , ν 1 + ν 2 + ν 3 , ν 1 + ν 3 , ν 2 + ν 3 , 3 ν 3 , ν 2 + 3 ν 3 and ν 1 + 3 ν 3 from 2000 to 4000 cm-1 near-infrared region has been recorded. Low temperature was used to limit the presence of hot bands. The spectrum has been analyzed thanks to the XTDS software package. Combining with previously observed weak difference bands in the far infrared region involving the v 1 , v 2 , v 3 =1 states, we are thus able to use the tensorial model to build a global fit of spectroscopic parameters for v 1 =1,2, v 2 =1, v 3 =1,2,3. The model constitutes a consistent set of molecular parameters and enable spectral rovibrational simulation for all multi-quanta transitions involving v 1 , v 2 and v 3 up to v 1 − 3 = 3 . Tests simulation on rovibrational transitions not yet rovibrationally assigned are presented and compared to new experimental data.

International audience; A recent paper [1] presents a high-resolution, high-temperature version of the Nitrogen Dioxide Spectroscopic Databank called NDSD-1000. The NDSD-1000 database contains line parameters (positions, intensities, self- and air-broadening coefficients, exponents of the temperature dependence of self- and air-broadening coefficients) for numerous cold and hot bands of the 14N16O2 isotopomer of nitrogen dioxide. The parameters used for the line positions and intensities calculation were generated through a global modeling of experimental data collected in the literature within the framework of the method of effective operators. However, the form of the effective dipole moment operator used to compute the NO2 line intensities in the NDSD-1000 database differs from the classical one used for line intensities calculation in the NO2 infrared literature [12]. Using Fourier transform spectra recorded at high resolution in the 6.3 μm region, it is shown here, that the NDSD-1000 formulation is incorrect since the computed intensities do not account properly for the (Int(+)/Int(-)) intensity ratio between the (+) (J = N+ 1/2) and (-) (J = N-1/2) electron - spin rotation subcomponents of the computed vibration rotation transitions. On the other hand, in the HITRAN or GEISA spectroscopic databases, the NO2 line intensities were computed using the classical theoretical approach, and it is shown here that these data lead to a significant better agreement between the observed and calculated spectra.

A new rovibrational study of the ν6 band of methyl iodide was conducted to obtain a rather complete line list. A new analysis of line positions was accomplished. The spectrum of this band has been first recorded using the Bruker IFS125HR Fourier transform spectrometer (FTS) at the AILES beamline of the SOLEIL Synchrotron facility and later with the Bruker IFS125HR FTS located at the LISA facility in Creteil. Altogether, about 10,000 lines were assigned for the ν6 and 2ν3 bands up to high quantum numbers (J ⩽ 85 and K ⩽ 20). Because of the large value of the 127I nuclear quadrupole hyperfine constant, a significant portion of these assignments concerns clusters of hyperfine subcomponents, which are easily observable at 11 μm. These infrared data were combined in a least squares fit together with the existing microwave data on rotational transitions within the v6 = 1 and v3 = 2 vibrational states to get the upper state rotational constants and interacting parameters for the v6 = 1 and v3 = 2 states. Due to the high values of quantum numbers achieved during this infrared analysis, the final energy level calculation accounts for aCx ( Δ l = ± 1 ; Δ K = ± 1 ) and an α ( Δ l = ∓ 1 ; Δ K = ± 2 ) types of Coriolis interactions coupling the v6 = 1 energy levels with those from the v3 = 2 and v2 = 1 states, respectively. On the other hand, it proved unnecessary to update the existing hyperfine parameters for the v6 = 1 and v3 = 2 states.

A tensorial formalism adapted to the case of symmetric-top molecules has been recently developed in Dijon (El Hilali et al., J Quant Spectrosc Radiat Transf 2010;111, 1305–1315) [18]. It is based on the O ( 3 ) ⊃ C ∞ v ⊃C3v group chain and allows a systematic expansion of the Hamiltonian and dipole moment operators, including all possible interactions for a given rovibrational polyad system. This suite of programs is used to analyze and simulate the mid-infrared spectrum of methyl iodide in order to test its performance. The v6 fundamental band has been recorded using the FTIR Bruker HR125 at the AILES beamline of the SOLEIL Synchrotron facility with the Globar internal source. 3882 lines up to J=61 were assigned and fitted with only 16 tensorial parameters.

International audience; The far infrared spectrum of cyanogen has been studied at high resolution to improve the rotational analysis of the ν5 band system around 234 cm−1. Present in the sample in natural abundances, both isotopologues N13CCN and 15NCCN have also been studied. The weak ν4-ν5 difference band centered at 270 cm−1 has been studied for the first time. On the basis of a global rovibrational analysis limited to the ν2, ν4, and ν5 modes, energy levels up to 2300 cm−1 have been considered to contribute to the overall spectrum intensity at room temperature leading to a new line list of 196,994 lines. The line intensity prediction has been used to correct previous line intensity measurements by taking into account line mixing. A new vibrational transition moment has been deduced and compared to new band intensity measurements obtained by low resolution studies which are also presented in this paper. The agreement between both approaches is very good and rules out the apparent disagreement between line intensity and band intensity measurements observed in the past. An intensity study of 15NCCN is also proposed here thanks to the availability of a pure sample. Those results open the way to the search for isotopologues of cyanogen in Titan's atmosphere.

OsO4 is a heavy tetrahedral molecule that may constitute a benchmark for quantum chemistry calculations. Its favorable spin statistics (due to the zero nuclear spin of oxygen atoms) is such that only A1 and A2 rovibrational levels are allowed, leading to a dense, but quite easily resolved spectrum. Most lines are single ones, instead of complex line clusters as in the case of other heavy spherical-tops like SF6, for instance. It is thus possible to fully assign and fit the spectrum and to obtain precise experimental effective molecular parameters. The strong ν 3 stretching fundamental has been studied a long time ago as an isolated band [McDowell RS, Radziemski LJ, Flicker H, Galbraith HW, Kennedy RC, Nereson NG, et al. Journal of Chemical Physics 1978;88:1513–21; Bobin B, Valentin A, Henry L. Journal of Molecular Spectroscopy 1987;122:229–41]. We reinvestigate here this region and perform new assignments and effective Hamiltonian parameter fits for the four main isotopologues (192OsO4, 190OsO4, 189OsO4, 188OsO4), by considering the ν 1 / ν 3 stretching dyad. A new experimental spectrum has been recorded at room temperature, thanks to a Bruker IFS 125 HR interferometer and using a natural abundance OsO4 sample. Assignments and analyses were performed thanks to the SPVIEW and XTDS softwares, respectively [Wenger Ch, Boudon V, Rotger M, Sanzharov M, Champion J-P. Journal of Molecular Spectroscopy 2008;251:102–13]. We provide precise effective Hamiltonian parameters, including band centers and Coriolis interaction parameters. We discuss isotopic shifts and estimate the band centers for the three minor isotopologues (187OsO4, 186OsO4, 184OsO4). The Q branches of the first two of them are clearly identified in the experimental spectrum.

The ν 9 fundamental band (C–C–C deformation) of propane (C 3 H 8 ) at 369 cm −1 has been studied at high-resolution (0.0011 cm −1 ) with spectra recorded using the synchrotron radiation from the French light source facility at SOLEIL coupled to a Bruker IFS 125HR Fourier transform spectrometer. A 2.526 m base multipass cell with optical paths from 10.296 to 151.78 m was used. In addition, a spectrum was also recorded using a conventional globar source. Comparison of these experimental spectra shows clearly the gain obtained on the signal-to-noise ratios with the synchrotron radiation. The spectra have been thoroughly analyzed and transitions up to J =65 and K a =33 have been assigned. The upper-state rotational levels were fitted using an A-type Watson Hamiltonian written in the I r representation. An accurate band center ν 0 ( ν 9 )=369.228080(25) cm −1 as well as accurate rotational and centrifugal distortion constants have been obtained and used to simulate a synthetic spectrum. These parameters should be useful to simulate hot bands of propane involving the 9 1 vibrational level as their lower state.

International audience; The Coherent Synchrotron radiation obtained at SOLEIL has allowed, for the first time, measurement of broad band absorption, Fourier Transform spectra in the sub-THz range at 0.001 cm -1 resolution, with a signal-to-noise ratio of 100 attained in a few hours. The technique has been applied to the observation of the pure rotational spectrum of propynal (HC≡CCHO) in the 250 -700 GHz range. The new data have allowed the determination of more precise values for rotational constants and for higher order rotational constants. The potential of the technique for rapid recording of rotational spectra in this energy range is outlined.

International audience; New Infrared absorption data have been obtained using isolation in solid argon and neon on copper carbonyl molecules, CuCO and Cu(CO) 2 , two very reactive molecules. For CuCO, all three fundamentals are now observed and it presents an unusually large matrix effect, in line with former results indicating a weak metal carbon interaction and a large total dipole moment. With help of isotopic effects, new data indicates unambiguously that Cu(CO) 2 is linear and presents a notably stronger metal-carbon interaction than CuCO. Quantum chemical calculation have been carried out at the CCSD(T) level for determining energies and structural properties, as well as spectroscopic observables. The results enable an assessment of the high stability of the Cu(CO) 2 molecule (first bond dissociation energy of 66 kJ/mole) which suggest that observation at room temperature is possible and give a first evidence of Renner effect on a penta-atomic molecule.

International audience; Following our recent study devoted to measurements of intensities of pure rotation lines of methane, room temperature far infrared spectra of methane diluted in nitrogen at five total pressures between 100 and 800 hPa have been recorded at the AILES beamline of the SOLEIL synchrotron. One hundred and five N-2 broadening coefficients of methane pure rotation lines have been measured in the 83-261 cm(-1) spectral range using multi-spectrum non-linear least squares fitting of Voigt profiles. Pressure-induced line shifts were not needed to fit the spectra to the noise level and line mixing effects were neglected. One hundred and seventy-six self broadening coefficients have also been measured in the 59-288 cm(-1) spectral range using the pure methane spectra recorded in our previous work. The measured N-2 broadening coefficients were compared to semi-classical calculations.

International audience; As a tetrahedral molecule, methane has no permanent dipole moment. Its spectrum, however, displays faint absorption lines in the THz region, due to centrifugal distorsion effects. This is important for planetary applications since this region is used to measure methane concentration in some planetary atmospheres, in particular on Titan. Up to now, all measurements relied either on some old low resolution infrared absorption spectra, or on high resolution Stark measurements for low J values only. Even if these results have been reexamined recently [E. H. Wishnow, G. S. Orton, I. Ozier and H. P. Gush, J. Quant. Spectrosc. Radiat. Transfer 103, 102-117 (2007)], it seemed highly desirable to obtain much more precise laboratory data. The high-intensity synchrotron radiation, combined with a 151.75 +/- 0.1 m optical path in a White cell and a Bruker IFS 125 HR FTIR spectrometer at the AILES beamline of SOLEIL, enabled us to record this very weak spectrum at high resolution for the first time. Spectra were obtained in the 50-500 cm-1 wavenumber range at 296 K and 9.91, 20, 50 and 100 mbar with a resolution of 0.00074, 0.00134, 0.0034 and 0.0067 cm-1 (FWHM of the sinc function), respectively. The rotational clusters are fully resolved and the good signal-to-noise ratio has enabled precise measurements of transition intensities (92 cold band lines and 96 Dyad-Dyad hot band lines, with normal abundance intensities in the range 2.10-26 to 1.10-24 cm-1/(molecule.cm-2)), yielding an accurate determination of the dipole moment derivatives. Such results should allow a better determination of CH4 concentration in planetary objects.