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The HITRAN database is a compilation of molecular spectroscopic parameters. It was established in the early 1970s and is used by various computer codes to predict and simulate the transmission and emission of light in gaseous media (with an emphasis on terrestrial and planetary atmospheres). The HITRAN com- pilation is composed of five major components: the line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, experimental infrared absorption cross-sections (for molecules where it is not yet feasible for representation in a line-by-line form), collision-induced absorption data, aerosol indices of refraction, and general tables (including partition sums) that apply globally to the data. This paper describes the contents of the 2020 quadrennial edition of HITRAN. The HITRAN2020 edition takes advantage of recent experimental and theoretical data that were meticulously validated, in particu- lar, against laboratory and atmospheric spectra. The new edition replaces the previous HITRAN edition of 2016 (including its updates during the intervening years). All five components of HITRAN have undergone major updates. In particular, the extent of the updates in the HITRAN2020 edition range from updating a few lines of specific molecules to complete replace- ments of the lists, and also the introduction of additional isotopologues and new (to HITRAN) molecules: SO, CH 3 F, GeH 4 , CS 2 , CH 3 I and NF 3 . Many new vibrational bands were added, extending the spectral cov- erage and completeness of the line lists. Also, the accuracy of the parameters for major atmospheric absorbers has been increased substantially, often featuring sub-percent uncertainties. Broadening param- eters associated with the ambient pressure of water vapor were introduced to HITRAN for the first time and are now available for several molecules. The HITRAN2020 edition continues to take advantage of the relational structure and efficient interface available at www.hitran.org and the HITRAN Application Programming Interface (HAPI). The functionality of both tools has been extended for the new edition.

High-sensitivity spectra of the main ozone isotopologue were recorded using a cavity ring-down spectrometer in the region 7920–8670 cm−1, which covers the range up to the dissociation threshold and higher. A sensitivity on the order of 2 × 10−11 cm−1 has been attained, which makes it possible to detect high-energy combination rovibrational bands up to ten vibrational quanta in the electronic ground state. Line positions and intensities are measured for these bands. Hot vibronic bands of the 16O3 isotopologue formed by transitions from the (100) and (020) electronic ground state levels to the excited 3A2 triplet state were recorded for the first time providing new information about the dependence of predissociation broadening on rotational quantum numbers.

International audience; Absorption spectra of humidified CO2 have been recorded at room temperature by cavity enhanced absorption techniques (CRDS and OFCEAS): (i) in three spectral ranges of the 1.6 μm window (5720-6045 cm-1; 6390-6460 cm-1 and 6570-6665 cm-1), (ii) in four narrow spectral intervals of the 2.3 μm window (4243-4255 cm-1; 4301.3-4302 cm-1; 4421.5-4440 cm-1 and 4518-4535 cm-1), and (iii) around 2853 cm-1. All these spectral ranges are situated in transparency windows of both H2O and CO2. The binary absorption coefficients (BCO2 -H2 O +BH2 O - CO2) are retrieved from low pressure spectra (

International audience; Room temperature absorption spectra of ammonia were recorded by high-resolution Fourier transform spectroscopy in the 4700-5600 cm −1 range at four pressures (13, 46, 140, and 304 Pa). Additionally, we use an existing Kitt Peak spectrum to extend the analysis up to 5650 cm −1. In total, 9110 absorption lines with intensity ranging from 1 × 10 −25 to 1.6 × 10 −20 cm/molecule were retrieved, for the two principal isotopologues. Another Kitt Peak spectrum was used to identify 505 15 NH 3 transitions within the experimental line list. The rovibrational assignments of the 14 NH 3 lines relied on the position and intensity agreement with the C2018 theoretical line list (Coles et al. JQSRT 2018;219 199-212) and were validated by the systematic use of Lower State Combination Difference (LSCD) relations. In the process, a number of intensity transfer between nearby transitions were identified. Finally, 6562 transitions were assigned to 61 vibrational bands of the main isotopologue, 14 NH 3 , representing over 99.8% of the C2018 integrated absorption at room temperature in the region. The upper state empirical energy of a total of 2215 rovibrational levels of 14 NH 3 were derived. Most of them are newly reported. The comparison with the current HITRAN2020 list is discussed. A recommended line list for ammonia in natural isotopic abundance is provided for the studied region.

The absorption spectrum of the O-18(3) isotopologue of ozone was recorded by cavity-ring-down spectroscopy between 7920 and 7985 cm(-1) with a routine noise equivalent absorption, alpha(min), on the order of a few 10(-11) cm(-1). This permitted to detect and analyze an extremely weak vibrational band assigned as 7 nu(1) + nu(3) following predictions from the ab initio potential energy surface reported in J Chem Phys 2013;139:134307. This is the most excited rovibrational band of the O-18(3) isotopologue detected so far. In total, 259 ro-vibrational transitions were measured and modeled using an effective Hamiltonian model. The vibrational dipole transition moment parameter of the band deduced from the analysis and the fit to 177 experimental line intensities was evaluated as 2.6 x 10(-6) Debye. The absorption coefficient of the recorded pure O-18(3) spectrum was found significantly smaller compared to that of the O-16(3) in the same range. The set of 171 upper state energies experimentally determined cover the range from 92.6% (at J = 1) to 97% (at J = 26) of the first dissociation threshold D-0. The comparison with ab initio predictions for the band origin and nu-dependent rotational constants is discussed. An absorption line list containing 477 transitions is provided as Supplementary material for the 7 nu(1) + nu(3) band. (C) 2021 Elsevier Ltd. All rights reserved.

International audience; Measurements of the water vapor absorption cross-sections at two spectral points of the 2.1 μm and 4.0 μm transparency windows are performed by optical feedback cavity enhanced absorption spectroscopy (OFCEAS). The self-continuum cross-section, C S , is measured for temperature values of 30 and 47 °C (303 and 320 K) at the 2853 cm −1 spectral point, corresponding to the lowest opacity region of the 4.0 μm transparency window. The C S values derived from the pressure squared dependence of the self-continuum, are found consistent with previous CEAS measurements in the considered window but significantly smaller than measurements by Fourier transform spectroscopy (FTS). The C S temperature dependence is discussed in relation with FTS measurements at high temperature. Foreign-continuum cross-sections, C F , are newly obtained from OFCEAS spectra of moist air in flow regime at the 4302 cm −1 spectral point of the low energy edge of the 2.1 μm window. After subtraction of the monomer and self-continuum contributions, C F values are derived from the linear variation of the foreign-continuum absorption with the product of the water vapor and air partial pressures. The measurements were performed for temperature values of 34 and 47 °C (307 and 320 K) and no significant temperature dependency was observed. The present C F value at 4302 cm −1 is gathered with previous CEAS measurements at seven spectral points of the 2.1 μm window. This consistent set of C F values is used to derive from a polynomial fit, the empirical frequency dependence of C F (ν) over the 4250-50 0 0 cm −1 range. Overall, the semi-empirical MT_CKD_3.5 values of C F are significantly underestimated in the centre of the considered window.

International audience; We investigate collisional line-shape effects that are present in highly accurate experimental spectra of the 3-0 S(1) and 2-0 Q(1) molecular hydrogen absorption lines perturbed by helium. We clearly distin-guish the influence of six different collisional effects (i.e.: collisional broadening and shift, their speed dependencies and the complex Dicke effect) on the shapes of H-2 lines. We demonstrate that only a very specific combination of these six contributions, determined from our ab initio calculations, gives unprece-dentedly good agreement with experimental spectra. If any of the six contributions is neglected, then the experiment-theory comparison deteriorates at least several times. We also analyze the influence of the centrifugal distortion on our ab initio calculations and we demonstrate that the inclusion of this effect slightly improves the agreement with the experimental spectra. (C) 2021 The Author(s). Published by Elsevier Ltd.

This paper describes the updates of the line positions and intensities for the carbon dioxide transitions in the 2020 edition of the HITRAN spectroscopic database. The new line list for all 12 naturally abundant isotopologues of carbon dioxide replaces the previous one from the HITRAN2016 edition. This update is primarily motivated by several issues related to deficient HITRAN2016 line positions and intensities that have been identified from laboratory and atmospheric spectra. Critical validation tests for the spectroscopic data were carried out to find problems caused by inaccuracies in CO2 line parameters. New sources of data were selected for the bands that were deemed problematic in the HITRAN2016 edition. Extra care was taken to retain the consistency in the data sources within the bands. The comparisons with the existing theoretical and semi-empirical databases (including ExoMol, NASA Ames, and CDSD-296) and with available experimental works were carried out. The HITRAN2020 database has been extended by including additional CO2 bands above 8000 cm−1, and magnetic dipole lines of CO2 were introduced in HITRAN for the first time by including the ν2+ν3 band in the 3.3-µm region. Although the main topic of this article is line positions and intensities, for consistency a recent algorithm for the line-shape parameters proposed in Hashemi et al. JQSRT (2020) was reapplied (after minor revisions) to the line list.

Room temperature absorption spectra of ammonia have been recorded by high-resolution Fourier transform spectroscopy in the range 3900-4700 cm−1 at four pressures (13, 46, 140, and 304 Pa). The investigated spectral region overlaps the important 2.3 µm atmospheric transparency window. 8419 absorption lines were retrieved from the recorded spectra. Line intensities range between 1 × 10−25 and 1.6 × 10−20 cm/molecule. The rovibrational assignments, relying on the position and intensity agreement with the C2018 theoretical line list (Coles et al. 2018), were validated by the systematic use of Lower State Combination Difference (LSCD) relations. 6052 transitions were assigned to 51 vibrational bands of the main isotopologue, 14NH3, and 625 transitions of the 15NH3 minor isotopologue were identified. Overall, the assigned transitions represent over 99.8% of the integrated absorption at room temperature in the region. The upper state empirical energy of a total of 2287 rovibrational levels of 14NH3 were derived. Among them, 1870 are newly reported. The achieved quality of the LSCD relations indicates that the accuracy of the derived energy levels is better than 0.001 cm−1. Comparison with the HITRAN2020 list shows that the present results will be valuable in improving the ammonia spectroscopic databases in the region, both in terms of completeness and accuracy of the line positions and line intensities. A recommended line list for ammonia in natural isotopic abundance is provided for the studied region.

International audience; We review progress, since publication of the book "Collisional effects on molecular spectra Laboratory experiments and models, consequences for applications" (Elsevier, Amsterdam, 2008), on measuring, modeling and predicting the influence of pressure (ie of intermolecular collisions) on the spectra of gas molecules. We first introduce recently developed experimental techniques of high accuracy and sensitivity. We then complement the aforementioned book by presenting the theoretical approaches, results and data proposed (mostly) in the last decade on the topics of isolated line shapes, line-broadening and-shifting, line-mixing, the far wings and associated continua, and collision-induced absorption. Examples of recently demonstrated consequences of the progress in the description of spectral shapes for some practical applications (metrology, probing of gas media, climate predictions) are then given. Remaining issues and directions for future research are finally discussed.

The weak low frequency tail of the ozone Wulf band is newly studied by high sensitivity cavity ring down spectroscopy (CRDS) in the 7920–8700 cm−1 range. Although strongly obscured by impurity lines, the ozone absorption signature shows up in the recorded spectra as two mostly unresolved absorption bands. These two bands with maximum near 8154 and 8450 cm−1 are hot bands from the (020) and (100) ground state vibrational levels reaching the same predissociated 3A2(000) upper state of 16O3. The observed bands include a mostly structureless continuum and lines exhibiting a clear broadening due to the predissociation of the 3A2(000) upper state. On the basis of assignments of the rotational structure available in the literature for the 3A2(000)-X1A1(000) cold band centered near 9553 cm−1, seventy-four relatively narrow lines could be rotationally assigned to the 3A2(000)-X1A1(020) and 3A2(000)-X1A1(100) hot bands. A line shape analysis, performed using a Voigt profile, provided the width of the Lorentzian component. Additional recordings performed at various pressures for 18 lines allowed to disentangle the pressure and predissociation contributions to the fitted Lorentzian widths. As a result, the newly derived pressure broadening coefficients of the considered rovibronic transitions are found to be similar to those of the rovibrational infrared bands. All the lines studied are affected by significant predissociation due the spin-orbit coupling between the 3A2(000) level and high lying dissociative vibrational levels of the X1A1 electronic ground state. The resulting set of predissociation widths for sixty lines ranges between 9 × 10−3 and 0.2 cm−1 corresponding to upper state lifetime of 560 and 25 ps, respectively. The reported results are discussed in relation with previous experimental and theoretical studies.

The weak high-resolution absorption spectrum of natural acetylene has been recorded by high sensitivity cavity ring down spectroscopy (CRDS) near 1.2 µm. The frequency scale of the spectra was obtained by coupling the CRDS spectrometer to a self-referenced frequency comb. The room temperature recordings, performed at a pressure of 10.0 Torr, cover the 8210–8670 cm−1 spectral interval. A list of more than 11,000 lines was constructed in the region. The smallest intensity values are on the order of 10−29 cm/molecule which is more than two orders of magnitude smaller than previous measurements by Fourier transform spectroscopy (FTS). More than 2600 lines were rovibrationally assigned using previous observations and predictions based on the effective operator approach. They include 2270, 338 and 28 absorption lines of 12C2H2, 12C13CH2 and 12C2HD, respectively, belonging to a total of 52 vibrational bands, thirty-six of them being newly reported. For comparison, the HITRAN2016 database provides line parameters of only two 12C2H2 bands, in the same region. Spectroscopic parameters of the upper vibrational levels were derived from standard band-by-band fits of the line positions (typical rms values of the (obs.-calc.) deviations are better than 0.002 cm–1). The vibrational transition dipole moment squared and Herman-Wallis coefficients of 39 bands were derived from a fit of the intensity values measured in this work and combined with previous FTS data for the strongest bands. A recommended list is constructed in the region using calculated line parameters for the unperturbed bands and experimental positions and intensities for the others. The recommended list including a total of 3139 transitions will help to complete acetylene spectroscopic databases in the near-infrared.

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).

The MERLIN mission (MEthane Remote LIdar missioN) is a space mission dedicated to the methane atmospheric retrieval based on absorption LIDAR measurements at nadir. The methane columns will be obtained by difference between the LIDAR signal at the on-line wavelength corresponding to the R(6) manifold of the 2ν3 band of methane at 6077 cm−1 and the off-line signal at a wavenumber about 1 cm−1 below. As atmospheric water vapor lines may affect the methane retrievals, the present study is dedicated to a detailed laboratory characterization of the interfering water vapor absorption in the targeted region. To this aim, high sensitivity absorption spectra of pure water vapor and water vapor in air are recorded at room temperature using a cavity ring down spectrometer (CRDS) combined with a self-referenced frequency comb. The CRDS recordings cover the 6071.4–6080.0 cm−1 interval with a noise equivalent absorption, αmin, on the order of 5 × 10−11 cm−1 for a 10−3 cm−1 sampling of the spectra. The measured pure and air-broadened spectra are analyzed using the Nelkin-Ghatak (NG) or the speed-dependent Nelkin-Ghatak (sdNG) profile. A multi-spectrum fitting procedure in which series of spectra recorded at different pressures (between 0.7 and 12 Torr for pure water vapor and between 100 and 700 Torr for H2O in air) are simultaneously adjusted, is used to retrieve the spectroscopic parameters. Accurate line parameters including self- and air-pressure shifts, self- and air-broadenings, Dicke narrowing and the speed-dependent coefficients are determined for most of the lines with intensity larger than 10−28 cm/molecule at 296 K. The list is complemented with literature data (in particular from the HITRAN database) to be complete down to a 10−29 cm/molecule intensity cut-off. The obtained spectroscopic results are discussed in comparison with literature data.

The high resolution absorption spectrum of the NO2 molecule is recorded between 5855 and 6006 cm−1 by high sensitivity cavity ring down spectroscopy (CRDS). Positions and intensities in the 5 × 10−27 − 4 × 10−23 cm/molecule range are derived from the profile fitting of more than 6900 lines. The absorption is dominated by the transitions of the (103)–(000) vibrational band centered at 5984.704 cm−1. The spectrum is assigned and modeled using an effective Hamiltonian (EH) which explicitly takes into account a spin–rotational interaction and interaction of the (103) bright state with three “dark” states: (122), (080) and (410). The ν1 + 3ν3 band was already analyzed by Fourier transform spectroscopy (FTS) in Miljanic S., Perrin A., Orphal J., Fellows C.E., Chelin, J. Mol. Spectrosc. 2008, V. 251, P. 9–15, where resonance interactions between the (103) state and the (122) and (080) “dark” states were taken into account. More than 3000 lines are presently assigned with rotational quantum numbers N and Ka up to 59 and 13, respectively, while 1147 transitions with maximum N and Ka values of 47 and 8, respectively, were previously identified by FTS. The measured line positions are reproduced with an (obs.-calc.) rms of 0.0023 cm−1 by variation of 41 EH parameters. About 80 transitions reaching the (080) highly excited bending upper state and borrowing their intensity from the resonance coupling with the (103)–(000) band were assigned for the first time. The main parameter in the transition moment series of the ν1 + 3ν3 band is determined from the fitting of the measured intensities.

The water vapor continuum absorption is studied in a spectral range covering most of the pure rotational spectrum of water molecule up to 500 cm−1. The continuum absorption was derived from the broadband water vapor spectra recorded by Fourier transform spectrometer equipped with the 151-m multipass gas cell at the AILES beam line of the SOLEIL synchrotron. The coherent (10–35 cm−1) and standard (40–500 cm−1) radiation modes of the synchrotron were used. In order to refine the magnitude and clarify the physical origin of the continuum, spectra of the two major water isotopologues, H216O and H218O, were considered. Recordings at several water vapor pressures were used to check the expected quadratic pressure dependence of the continuum. The new data extend and supplement previous measurements filling, in particular, the gap between 200 and 350 cm−1, which was never studied before. The H216O and H218O absorption continua in the range of 50–650 cm−1 show similar frequency dependence and magnitude. In particular, both continua exhibit a clear water dimer spectral signature near 15 cm−1, in good agreement with previous ab initio calculations. The present data confirm that the MT-CKD empirical continuum model widely used in atmospheric applications, overestimates importantly the continuum magnitude in the whole range of the rotational band. The observed irregular frequency dependence of the retrieved self-continuum cross-section values is tentatively interpreted as due to uncertainties on the resonance lines of the water monomer spectrum which is subtracted from the recorded spectra. On the basis of spectra simulations, the inadequate description of the line shapes in the range of the intermediate wings (detuning of 5–10 cm−1 from line center) and the uncertainties on the self-broadening coefficients of water monomer lines are identified as possible mechanisms responsible of the observed irregular fluctuations.

We revisit the room temperature absorption spectrum of natural nitrous oxide recorded by high sensitivity cavity ring down spectroscopy between 7647 and 7918 cm(-1) (1.31-1.26 mu m) reported by Liu et al. (doi: 10.1016/j.jms.2011.03.025). In this previous analysis, 2272 transitions could be assigned in the region and no intensity information was provided. In the present work, on the basis of improved predictions of the effective operator models, the assignments could be extended to more than 3200 transitions and, more importantly, line intensities are provided for all the transitions. The assigned transitions belong to 49 bands of the (N2O)-N-14-O-16, (NNO)-N-14-N-15-O-16, (NNO)-N-15-N-14-O-16, (N2O)-N-14-O-18, and (N2O)-N-14-O-17 isotopologues, 16 being newly assigned. All the identified bands correspond to the ?P= 14 series of transitions, except for four ?P= 12 and two ?P= 13 bands of the (N2O)-N-14-O-16 isotopologue (P= 2V(1)+V-2+4V(3) is the polyad number where V-i= 1-3 are the vibrational quantum numbers). For comparison, the HITRAN2020 database includes only the nu(1)+3 nu(3) band of the main isotopologue and a number of calculated line parameters for the fourth minor isotopologue, (N2O)-N-14-O-18. The band-by-band analysis provides accurate spectroscopic parameters of 46 bands from a fit of the measured line positions. Nine resonance perturbations were identified including a few extra lines for two (N2O)-N-14-O-16 bands. The interaction mechanisms and the perturbers were assigned on the basis of the effective Hamiltonian models. The comparison with current spectroscopic databases (HITRAN, HITEMP, NOSD) is discussed. All show significant deviations compared to our observations (e.g. for ?P= 13 band intensities). The reported results will be thus valuable to more accurately account for the absorption of nitrous oxide in the region. (C) 2022 Elsevier Ltd. All rights reserved.

International audience; A collision induced absorption (CIA) band has been measured near 6000 cm$^{-1}$ in a spectrum of humidified CO$_2$ recorded by cavity ring down spectroscopy (CRDS) at low pressure (

The recent detections of electric-quadrupole (E2) transitions in water vapor and magnetic-dipole (M1) transitions in carbon dioxide have opened a new field in molecular spectroscopy. While in their present status, the spectroscopic databases provide only electric-dipole (E1) transitions for polyatomic molecules (H$_2$O, CO$_2$, N$_2$O, CH$_4$, O$_3$…), the possible impact of weak E2 and M1 bands to the modeling of the Earth and planetary atmospheres has to be addressed. This is especially important in the case of carbon dioxide for which E2 and M1 bands may be located in spectral windows of weak E1 absorption. In the present work, a high sensitivity absorption spectrum of CO$_2$ is recorded by Optical-Feedback-Cavity Enhanced Absorption Spectroscopy (OFCEAS) in the 3.3 µm transparency window of carbon dioxide. The studied spectral interval corresponds to the region where M1 transitions of the $ν_{2}+ν_{3}$band of carbon dioxide were recently identified in the spectrum of the Martian atmosphere. Here, both M1 and E2 transitions of the $ν_{2}+ν_{3}$ band are detected by OFCEAS. Using recent ab initio calculations of the E2 spectrum of $^{12}$C$^{16}$O$_2$, intensity measurements of five M1 lines and three E2 lines allow us to disentangle the M1 and E2 contributions. Indeed, E2 intensity values (on the order of a few 10$^{–29}$ cm/molecule) are found in reasonable agreement with ab initio calculations while the intensity of the M1 lines (including an E2 contribution) agree very well with recent very long path measurements by Fourier Transform spectroscopy. We thus conclude that both E2 and M1 transitions should be systematically incorporated in the CO$_2$ line list provided by spectroscopic databases.

The weak high-resolution absorption spectrum of natural nitrous oxide has been recorded by high sensitivity cavity ring down spectroscopy (CRDS) near 1.18 µm. The frequency scale of the spectra was obtained by coupling the CRDS spectrometer to a self-referenced frequency comb. The room temperature recordings, performed with a pressure of 1 Torr, cover the 8325-8622 cm−1 spectral interval where previous observations were very scarce. More than 3300 lines belonging to four N2O isotopologues (14N216O, 14N15N16O, 15N14N16O, and 14N218O) are measured with a position accuracy better than 1 × 10−3 cm−1 for most of the lines. Line intensities at room temperature range between 1.2 × 10−25 and 3.8 × 10−30 cm/molecule. The rovibrational assignments were obtained by comparison with predictions based on the global modeling of the line positions and intensities performed within the framework of the method of effective operators. The band-by-band analysis led to the determination of the rovibrational parameters of a total of 47 bands. All identified bands belong to the ΔP= 14-16 series of transitions, where P=2V1+V2+4V3 is the polyad number (Vi= 1-3 are the vibrational quantum numbers). Among these bands, only five were previously observed and bands of the ΔP= 15 series are reported for the first time. Local resonance perturbations affecting two bands are identified and analyzed. The position and intensity comparisons to the HITRAN2016 and HITEMP2019 spectroscopic databases are discussed. The HITRAN line list is limited to only four (calculated) bands of the 14N218O isotopologue in the studied region while ΔP= 15 bands are missing in the HITEMP list. The present work will help to improve future versions of the spectroscopic databases of nitrous oxide, a strong greenhouse gas. © 2021 Elsevier Ltd This work is jointly supported by CNRS (France) in the frame of the International Research Project “ SAMIA ” with IAO-Tomsk.

We investigated the continuum absorption of water vapour diluted in nitrogen, oxygen and air in the range of the pure rotational band of the water molecule (50-500 cm−1). Spectra recordings were performed at room temperature with a Fourier transform spectrometer associated to a 151-m multipass gas cell located at the AILES beamline of SOLEIL synchrotron facility. The study includes the first laboratory measurements in the wide 90-330 cm−1 interval. Tests of the baseline stability, crucial for the continuum determination, are reported together with the expected pressure dependences of the continuum absorption, measured over different pressure ramps. Retrieved foreign-continuum cross-sections are found in good agreement with literature values available in the lower and upper parts of the studied frequency range. The reported results validate the MT_CKD foreign-continuum empirical model, widely used in atmospheric applications, even if some overestimation of the MT_CKD values is noted in the centre of the band where experimental data were absent.

International audience; The room temperature spectrum of the very weak third overtone band of carbon monoxide in natural isotopic abundance is recorded by cavity ring down spectroscopy (CRDS) referenced to a frequency comb, between 8206 and 8465 cm-1. The sensitivity of the recordings (noise equivalent absorption on the order of min~ 5×10-12 cm-1) allowed for measuring lines with intensity as weak as 1×10-30 cm/molecule at a recording pressure limited to 10.0 Torr. The use of low pressure values (1.0 and 10.0 Torr) helped to minimize the impact of profile effects on the derived line positions and line intensities. The line profile analysis was performed using the speed dependent Nelkin-Ghatak model for the 10 Torr recordings while the Voigt profile was found sufficient to account for the line shapes recorded at 1.0 Torr. Overall, line parameters of 227 transitions are derived. The observed transitions belong to the 4-0 band of the 12C16O, 13C16O, 12C18O and 12C17O isotopologues present in natural abundance in the sample and to the 5-1 hot band of 12C16O. For a large part of the observations, line positions are reported with accuracy as good as 4×10-6 cm-1 (~120 kHz). The selfinduced line shift of the 4-0 band is reported for the first time from the position values at 1 and 10 Torr. Using literature values of the 1-0, 2-0 and 3-0 bands, the vibrational dependence of the self-induced pressure shift in CO is discussed. The experimental values of the 12C16O v= 4 energy levels J < 26 are reproduced with a standard deviation of 2.5×10-6 cm-1 (75 kHz). The intensities of the 12C16O lines reported with an accuracy better than 1% show an overall good agreement with literature values in particular with those included in the HITRAN database.

The oxygen A-band near 760 nm is used to determine the air-mass along the line of sight from ground or space borne atmospheric spectra. This band is located in a spectral region of very weak absorption of water vapor. The increased requirements on the determination of the air columns make suitable to accurately characterize water absorption spectrum in the region. In the present work, we use a cavity ring down spectrometer newly developed in Tomsk, to measure with unprecedented sensitivity and accuracy the water spectrum in the 12969 - 13172 cm−1 region. While about fifty transitions were previously detected in the region, a total of about 580 water lines are measured by CRDS and rovibrationally assigned, leading to the determination of 103 new levels and correction of 134 levels of H216O. Spectroscopic line lists available in the region (HITRAN, W2020 and theoretical line lists) show some important deviations compared to observations. In particular, line intensities are poorly predicted by available ab initio calculations for transitions involving a highly bending excitation. © 2021 Elsevier Ltd. The support of the CNRS (France) in the frame of International Research Project SAMIA is acknowledged. CRDS measurements and spectrum analysis were performed at IAO-Tomsk and funded by RFBR project 20-32-70054.

Series of spectra of the S(0) and Q(1)-Q(4) transitions of the (2-0) band of D2 near 5860 cm−1 are recorded by comb-referenced cavity ring down spectroscopy, at four pressures up to 200 Torr. After averaging, high resolution (30 MHz step) and low noise (noise equivalent absorption, αmin≈ 1.5 × 10−11 cm−1) spectra are obtained for each pressure value. This leads to signal to noise ratios of several hundred for the considered very weak electric quadrupole transitions with intensities ranging between 4 × 10−29 and 4 × 10−28 cm/molecule. The Q(3) and Q(4) transitions are newly detected. A multi-spectrum treatment of the D2 line profiles at different pressures performed using a quadratic speed-dependent Nelkin-Ghatak profile leads to residuals close to the noise level. Considering statistical fit errors and possible biases, total uncertainties on the frequencies extrapolated at zero pressure are estimated to be between 0.30 MHz and 1.83 MHz. The derived experimental frequencies and intensities of (2-0) transitions are gathered with literature values and compared to ab initio values reported in J. Komasa, M. Puchalski, P. Czachorowski, G. Łach, K. Pachucki, Phys. Rev. A 100, 032519 (2019). An agreement within the combined uncertainties is achieved for the S(0), Q(1), Q(2) and Q(3) transitions. Line intensities are also discussed in relation with literature values.

The rotational spectrum of water vapour highly enriched in 18O has been studied by high resolution (≈ 0.001 cm−1) Fourier transform spectroscopy at the AILES beam line of the SOLEIL synchrotron. The room temperature absorption spectrum has been recorded between 40 and 700 cm−1. The 18O enrichment of the sample was about 97% while the gas pressure and the absorption pathlength were set to 0.97 mbar and 151.75 m, respectively. The spectrum contains more than 4800 rotational transitions from seven water isotopologues (H218O, H216O, H217O, HD18O, HD16O, HD17O, D218O). The assignments were performed using known experimental energy levels as well as calculated line lists based on the results of Schwenke and Partridge. The amount and accuracy of the reported line positions represent an important extension compared to previous works. Overall, lines of about 2570 transitions are observed for the first time and 35, 41, 50, and 16 new energy levels are determined for H218O, H217O, HD18O, and HD17O, respectively. The set of derived energy levels shows a number of important differences from those recommended by an IUPAC-task group. Compared to the HITRAN2016 database, numerous deviations of line positions (up to 0.15 cm−1) are found for the H217O, H218O, HD17O, and HD18O species. Incomplete and wrong HITRAN's assignments of more than 90 transitions for H218O, H217O and HD18O are identified. Overall, the measured line positions will allow to significantly refine and complete the sets of empirical energy levels of H218O, H217O, HD18O and HD17O in the ground vibrational state.

A room temperature Fourier Transform absorption spectrum of ammonia measured in 1991 and available from the Kitt Peak data center is analyzed in the 5650 - 6350 cm−1 region. This spectral interval is part of the important 1.6 µm atmospheric transparency window where ammonia could be detected as trace species. The centers and intensities of 2779 ammonia lines were retrieved using a multiline fitting procedure. The spectrum was assigned by the joint use of a recent variational line list and of lower state combination difference relations. Overall, 1762 lines were assigned to 29 bands providing 914 new experimental energies. The obtained assignments and upper state experimental energies are the first for ammonia in the studied region. The comparison of our line list to the variational line list, to the HITRAN2016 list and to a very recent experimental line list is presented and discussed.

The very weak absorption spectrum of natural CO2 is studied at high sensitivity near 1.18 µm. The investigated region corresponds to a transparency window of particular interest for Venus. Low pressure (10 Torr) spectra are recorded with unprecedented sensitivity in the 8311–8679 cm−1 interval. A noise equivalent absorption, αmin, on the order of 5 × 10−12 cm−1 is achieved using a cavity ring down spectrometer (CRDS) coupled with a self-referenced frequency comb. 669 lines are accurately measured and rovibrationnally assigned to 15 bands of the three first carbon dioxide isotopologues, 12C16O2, 13C16O2 and 16O12C18O. For all but one band, line intensities are smaller than 10−28 cm/molecule at 296 K and the weakest lines have intensity as low as 5 × 10−31 cm/molecule. In the large 8310–8645 cm−1 interval where no CO2 absorption lines were previously detected, about 500 lines are measured. In spite of the weakness of the considered transitions, line centers could be accurately determined and spectroscopic parameters are determined from standard band-by-band fit of the line positions (typical rms deviations are 5 × 10−4 cm−1). These newly observed bands provide critical validation tests for the most recent spectroscopic databases of carbon dioxide. The comparison to the recent updated version of the Carbon Dioxide Spectroscopic Databank (CDSD2019), to the current HITRAN2016 database and ab initio line lists is presented. The CDSD and HITRAN positions deviate from the measurements by less than 0.01 cm−1. Measured line intensities show an overall good agreement in particular with ab initio values but reveal that a few bands have inaccurate intensities in HITRAN2016 and CDSD2019. Three very weak bands are missing in CDSD2019. The reported experimental information will help to improve the quality of the CO2 spectroscopic databases in the region.

The oxygen absorption spectrum in the 50–170 cm-1 spectral range is studied at the AILES beam line of the SOLEIL synchrotron with a Fourier transform spectrometer equipped with a 151-m multipass gas cell. The spectrum recorded at room temperature (23.15 °C) with a pressure of 19.76 Torr is formed by weak pure rotational magnetic dipole transitions. Line parameters of 26 lines are derived and compared to literature values. In particular, measured line intensities confirm the 45 years-old previous values reported by Boreiko et al. (J. Quant. Spectrosc. Radiat. Transfer 32 (1984)109–117). The agreement with HITRAN intensities (within 1% level for the strongest lines) indicates that the 20% HITRAN error estimate was overly cautious: we show that the error is more likely within 2%.

The room temperature absorption spectrum of 13CH4 is recorded by high sensitivity cavity ring down spectroscopy (CRDS) near 1.58 µm. The investigated region (6147–6653 cm−1) corresponds to a spectral region of weak absorption located between the strong bands of the tetradecad and icosad. The sensitivity of the recordings allowed for the measurement of more than 13000 lines for which line centers and line intensities are derived using a multiline fitting program. The obtained list is the first extensive list of 13C enriched methane in the region. It is believed to include a significant number of lines of 13CH3D. In addition, 185 lines were measured at 80 K by direct absorption spectroscopy (DAS) near 6600 cm−1. The line intensity detectivity threshold is on the order of a few 10−29 cm/molecule for the CRDS recordings at 296 K and 10−26 cm/molecule for the DAS recordings at 80 K. From the intensity ratio of the lines in common in the 296 K and 80 K empirical line lists near 6600 cm−1, 438 empirical values of the lower state energy level (Eemp) were derived. An additional set of 200 Eemp values were obtained by combining the present CRDS line intensities to DAS literature data near 6150 cm−1. The comparison to the TheoReTS ab initio line list shows an overall very good agreement for the line intensities. Significant deviations on the order of 0.1 cm−1 are noted for line positions. The obtained experimental data will be valuable to tune ab initio line positions to empirical values in future versions of the theoretical line lists. Finally, a first set of 900 lines belonging to the 5ν4 and ν2 + 4ν4 bands of the icosad are rovibrationally assigned on the basis of an effective Hamiltonian model. The energy values of the involved vibrational sublevels are reported.

Water vapour foreign-continuum absorption cross-sections, CF, are measured for the first time at room temperature in the 1.6 µm transparency window, of importance for atmospheric applications. The measurements are performed by cavity ring down spectroscopy (CRDS) at 15 selected spectral data points. These data, covering the 5700–6640 cm−1 spectral range, are derived from the variation of the absorption signal during pressure ramps of humidified air up to 1 atm with a typical 1% water vapour relative concentration. The foreign-continuum absorption was obtained as the excess of the measured loss rate compared to the sum of the loss rate measured with dry air, the local water monomer contribution and the self-continuum absorption. CF values were derived from the linear dependence of the foreign-continuum absorption with the product of the partial pressures of water vapour and air. The semi-empirical MT_CKD CF values are found significantly underestimated in the centre of the window.

A high-sensitivity absorption spectrum of natural nitrous oxide has been recorded at 10 Torr between 8321 and 8620 cm−1 (1.20 – 1.16 µm). The used cavity ring down spectrometer was referenced to a self-referenced frequency comb providing an accurate frequency scale of the spectra. The predictions of effective operator models were used for the line assignment. All identified bands correspond to the ΔP=14-16 series of transitions, where P= 2V1+V2+4V3 is the polyad number (Vi=1-3 are the vibrational quantum numbers). A total number of 3975 transitions belonging to the 14N216O, 14N15N16O, 15N14N16O,14N218O, and 15N216O isotopologues were measured with estimated accuracy better 1 × 10−3 cm−1 for most of the lines. Compared to the recent analysis of N2O spectra at 1 Torr recorded in the same region (Karlovets et al. JQSRT, 262 (2021) 107508, doi: 10.1016/j.jqsrt.2021.107508), the higher pressure of the recordings and improved quality of the predictions have allowed to: (i) newly assign twenty-two bands, including the 4ν3 band of the 15N216O minor isotopologue, (ii) extend the assignments of previously known bands, (iii) determine the small self-induced pressure shifts of the two strongest bands (less than 10−4 cm−1) by difference of the line positions at 1 and 10 Torr and use them to obtain the zero-pressure value of the line positions, (iv) derive new or improved spectroscopic constants of 69 bands from the standard band-by-band analysis, and (v) analyze six local resonance perturbations affecting three bands, including the identification of a few extra lines due to intensity transfer. Finally, the comparison of the line positions and intensities with their predicted values and with available databases is discussed.

The very weak absorption spectrum of natural CO2 near 1.74 µm (5702–5879 cm−1) is studied at high sensitivity. The investigated region corresponds to a transparency window of very weak opacity which is of particular interest for Venus. Very weak lines with intensity value as low as 10−30 cm/molecule at 296 K are detected by Cavity Ring Down Spectroscopy. On the basis of the predictions of effective Hamiltonian models, 1135 lines of six carbon dioxide isotopologues - 12C16O2, 13C16O2, 16O12C18O, 16O12C17O, 16O13C18O and 16O13C17O - were rovibrationnally assigned to 26 bands. The accurate spectroscopic parameters of 16 bands are determined from standard band-by-band analysis (typical rms deviations of the line positions are 8 × 10−4 cm−1). These newly observed bands include perturbed bands, weak hot bands and bands of minor isotopologues (in particular 16O12C18O in natural abundance) and provide critical validation tests for the most recent spectroscopic databases. The comparison to the Carbon Dioxide Spectroscopic Databank (CDSD), HITRAN2016 database and recent ab initio line lists is presented. Deficiencies are evidenced for some weak perpendicular bands of the HITRAN2016 list and identified as due to inaccurate CDSD intensities which were preferred to ab initio intensities. While Ames and UCL ab initio intensities are believed to be accurate within a few % for the strong unperturbed bands, the reported measurements allow testing important (>50%) differences between ab initio values of some weak perturbed bands.

A decade ago, a task group of the International Union of Pure and Applied Chemistry performed an exhaustive collection and review of measured transitions, applied the MARVEL procedure, and derived recommended empirical energy levels for nine major water isotopologues. Very recently, using an improved methodology, the sets of empirical energy levels of H216O, H218O and H217O were updated, leading to the so-called W2020 energy levels and transition wavenumbers [Furtenbacher et al. J. Phys. Chem. Ref. Data 49 (2020) 043103; 10.1063/5.0030680]. Here we present validation tests of the W2020 line list of H216O against spectra recorded by cavity ring down spectroscopy (CRDS) referenced to a frequency comb (FC), newly obtained in the 8040-8630 cm−1 region. The recorded spectra are found in excellent agreement with previous high-quality studies available in the literature. While these literature sources were all incorporated in the transition database used to derive the W2020 energy levels, the direct superposition of the FC-CRDS spectra to the W2020 line list of H216O shows a number of large disagreements. Cases where deviations largely exceed the W2020 claimed uncertainty on the transition frequencies are noted. In the considered spectral region, the resulting W2020 list is thus less accurate than some of the published original sources used to derive the W2020 energy levels. We conclude that the sophisticated global procedure and algorithm elaborated to identify and adequately weight inaccurate line positions among the large W2020 transition database do not always prevent less accurate data from “spoiling” higher quality data sources. The W2020 list of H216O is also compared to newly recorded CRDS spectra in the 12970–13200 cm−1 region (corresponding to the region of the A-band of O2), where previous observations were very scarce. As in the previous region, substantial position deviations are evidenced, and in many cases, the W2020 error bars appear to be strongly underestimated.

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The atmospheric band of O2 near 1.27 µm plays an important role in determining the sounded air-mass from ground or space borne atmospheric spectra. This band consists of narrow absorption lines of the a 1 Δ g − X 3 Σ g − ( 0 − 0 ) transitions superimposed to a much broader collision-induced absorption structure. The present contribution is part of a long standing project aiming to improve different aspects of the spectroscopy of this band by highly sensitive cavity ring down spectroscopy (CRDS). In the present contribution, low pressure (5 and 10 Torr) spectra of pure O2 were recorded with unprecedented sensitivity in the 7920–8085 cm−1 interval (noise equivalent absorption, αmin, on the order of 10−12 cm−1) using an external cavity diode laser. About 170 lines including electric quadrupole transitions were accurately measured. The weakest lines have intensity on the order of 10−30 cm/molecule. The coupling of the CRDS spectrometer with a self-referenced frequency comb allows for an important gain on the accuracy of the line center determination. Detailed line profile analysis using the quadratic speed-dependent Nelkin-Ghatak profile was performed for a series of twelve lines recorded for pressures up to 150 Torr. In particular, the very weak self-pressure shifts (on the order of 10−3 cm−1/atm) could be determined for the first time. Line intensities with uncertainty of 1% are reported for lines with intensity larger than 10−28 cm/molecule. Accurate spectroscopic parameters of the a1Δg(v = 0) upper level were fitted to the zero-pressure line centers. An rms value of 108 kHz (3.6 × 10−6 cm−1) is achieved for the (meas.-calc.) differences of the 16O2 a1Δg(v = 0) upper level (Jmax= 37). Significant deviations compared to the HITRAN database are discussed.

The high-resolution absorption spectrum of acetylene has been recorded at room temperature by high sensitivity cavity ring down spectroscopy (CRDS) in the 5693–5882 cm–1 region. The noise level of the recordings corresponds to a typical minimum detectable absorption, αmin, below 10-10 cm−1. The positions and intensities of about 4000 lines were determined and analyzed together with about 3900 lines left unassigned in a previous CRDS study in the 5850–6340 cm−1 region. In total, about 2620 12C2H2 and 250 12C13CH2 absorption lines are assigned in the present work, most of them being newly reported. The 12C2H2 lines belong to 53 bands and include 24 bands newly identified or improved in the region of the previous study. Altogether, 107 bands in the entire 5693–6340 cm−1 while the HITRAN database provides line parameters of only nine 12C2H2 bands in the same region. The lines of 12C13CH2 in normal abundance (2.2%) belong to eight bands whose intensities are reported for the first time. Spectroscopic parameters of the upper vibrational levels were derived from standard band-by-band fits of the line positions (typical rms values of the (obs.-calc.) deviations are better than 0.002 cm–1). The vibrational transition dipole moment squared and Herman–Wallis coefficients of each band were derived from a fit of the measured intensity values. A recommended line list is provided for the bands newly assigned with positions calculated using empirical spectroscopic parameters of the lower and upper energy vibrational levels and intensities computed using the derived Herman–Wallis coefficients. As a result, the constructed line list includes a total of 4471 transitions belonging to 53 bands of 12C2H2 and 8 bands of 12C13CH2. This list of acetylene transitions above 5693 cm−1 extends to lower energy and completes our empirical spectroscopic database for acetylene in the 5850–9415 cm−1 range.

In spite of being a greenhouse gas with a large global warming potential, the absorption spectrum of nitrous oxide in the near infrared is insufficiently characterized. In the present work, the spectral region near 1.74 µm (5696–5910 cm−1) is investigated by high sensitivity cavity ring down spectroscopy (CRDS). The noise level of the CRDS spectra corresponds to a typical minimum detectable absorption, αmin, below 10-10 cm−1. 3326 transitions are measured and rovibrationally assigned to 50 bands of five nitrous oxide isotopologues (14N216O, 14N15N16O, 15N14N16O, 14N218O and 14N217O) in natural isotopic abundance. The assigned weakest lines have an intensity below 10−28 cm/molecule. For comparison, only three 14N216O bands are included in the HITRAN database in the region, with a 2 × 10−25 cm/molecule intensity cut off. The rovibrational assignments were performed by comparison with predictions performed for each isotopologue in the frame of the effective operator approach. The overall quality of the predictions is satisfactory for line positions. Deviations larger than 0.1 cm−1 are nevertheless noted for 14N216O and 14N218O. The spectroscopic parameters of the upper level of the observed bands were derived from the standard band-by-band fit of the measured line positions. A significant number of bands were found to be perturbed by local rovibrational perturbations and in some cases, extra lines due to an intensity transfer could be assigned. The interaction mechanisms and the perturbers were univocally identified on the basis of the effective Hamiltonian model. In particular, interpolyad couplings were evidenced indicating that the polyad version of the effective Hamiltonian has to be extended to include Coriolis and interpolyad anharmonic interactions. No satisfactory modeling of the N2O line intensities is yet available in the region. The CRDS intensity values derived in this work provide a solid set of measurements for future semi-empirical intensity modeling in the region.

New measurements of the water vapour continuum in the 1.6 µm and 2.3 µm windows are obtained at room temperature using highly stable and sensitive cavity ring down (CRD) spectrometers. In the 1.6 µm window, self-continuum cross-sections, CS, are derived for 30 selected spectral points between 5700 and 6850 cm−1 using pressure ramps of pure water vapour (up to 15 Torr). Purely quadratic pressure dependence is obtained for each measurement point. Compared to our previous dataset (Mondelain et al., 2014), the retrieved Cs values are more accurate and show a general agreement. The spectral coverage is extended both on the high and low frequency edges of the 1.6 µm window. In addition, new CS values are derived in the 5120–5137 cm−1 interval extending to higher energy the coverage of the 2.3 µm window. The measurements near 5700 cm−1 and 5130 cm−1 are found lower than the MT_CKD_3.2 values by a factor of about 2 and 1.5, respectively. Foreign-continuum cross-sections, CF, are newly obtained in the 2.3 µm window from CRDS spectra of moist air in flow regime. Spectra were recorded for different water vapour partial pressures while maintaining the total pressure constant in the high finesse CRDS cavity. After subtraction of the monomer and self-continuum contributions, CF values were derived from the linear variation of the foreign-continuum absorption with the water vapour partial pressure. CF values determined at four spectral points between 4430 and 5000 cm−1 are larger by up a factor of five than the corresponding MT_CKD values. Considering these CRDS data at room temperature and literature values at 400 K the temperature dependence of the foreign-continuum is confirmed to be weak.

Highly sensitive cavity enhanced laser techniques are used for accurate measurements of the absorption of dinitrogen (N2) at two spectral points of the fundamental and first overtone bands. Spectra of pure N2 and of a N2/O2 mixture were recorded near 2491 and 4720 cm−1 by Optical Feedback Cavity Enhanced Absorption Spectroscopy (OF-CEAS) and Cavity Ring Down Spectroscopy (CRDS), respectively. The noise level of the OF-CEAS and CRDS spectra corresponds to a minimum detectable absorption, αmin, of about 10-9 and 10-11 cm−1, respectively. Measurements involve both the N2 collision-induced absorption (CIA) bands and the very weak 2–0 S(10) and S(11) electric quadrupolar transitions. Accurate CIA binary coefficients, B N 2 − N 2 and B N 2 − O 2 , are derived from the pressure-squared dependence of the baseline level of the spectra recorded at pressures below 1 atm. These CIA values are compared to previous determinations from high pressure spectra (up to 90 atm) and to recent classical molecular dynamics simulations (CMDS). An overall good agreement is obtained although a significant deviation is observed for the first overtone CIA near 4720 cm−1. The line position and intensity (on the order of a few 10−30 cm/molecule) of the 2–0 S(10) and S(11) electric quadrupolar transitions are determined experimentally for the first time and compared to theoretical values provided in the HITRAN2016 database.

The room temperature absorption spectrum of 17O enriched carbon dioxide is investigated by high sensitivity cavity ring down spectroscopy (CRDS) between 5695 and 5850 cm−1. About 1100 lines are measured and assigned to 26 bands of the six 17O containing carbon dioxide isotopologues: 16O12C17O, 16O13C17O, 17O12C18O, 17O13C18O, 12C17O2 and 13C17O2. The set of observed lines are rovibrationnally assigned on the basis of the predictions of the effective Hamiltonian (EH) model. The observed bands belong to the ΔP = 8 and 9 series of transitions where P = 2 V1 + V2 + 3 V3 is the polyad number (Vi being the vibrational quantum numbers). They consist in 12 previously unobserved bands and 14 already-known bands, for which additional high J lines are assigned. Bands of the 12C17O2 and 13C17O2 isotopologues (two for each) are observed for the first time in this spectral interval. The spectroscopic parameters of the upper vibrational levels are determined from a band-by-band fit of the line positions (typical rms deviations are less than 0.001 cm−1). The comparison to the most recent carbon dioxide spectroscopic databases is presented. The reported data will be used to improve the modeling of the line positions of 17O containing carbon dioxide isotopologues.