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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).

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.

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.

The consistency of all data that have been published to date on the rovibrational line centers of the hydrogen chloride molecule HCl is analyzed. It was revealed that a number of corrections are needed because of systematic inaccuracies in the line center determination. A simultaneous fit of rovibrational transition frequencies was performed in the region from 7.4 to 18075 cm–1. The isotopically independent spectroscopic parameters for calculating rovibrational energy levels in the ground electronic state are determined. The calculated line centers are compared with the HITRAN data. The obtained spectroscopic parameters are used to calculate the turning points (rmin and rmax) of RKR-potentials of HCl isotopologues. The use of experimental data, including the highest vibrational state with Vmax = 8 that lies approximately at half the potential well depth allowed the pointwise potentials to be calculated up to Vmax = 20.

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.

Accurate knowledge of line parameters, and particularly line intensities is of primary importance for satellite, ground based and balloon measurements of the ozone concentration in the atmosphere. Self-consistency in absolute band intensities of ozone in various spectral intervals is necessary to avoid discrepancies in the atmospheric ozone retrieval from different windows. Difficulties in precise experimental characterization of absolute line intensities of this unstable molecule are well known leading to many significant deviations in published intensity values and in spectroscopic compilations. Ab initio intensities computed from the dipole moment functions of our previous works (Tyuterev et al. JCP 2017;146:064304; JCP 2019;150:184303) have permitted achieving a consistency between Stark-effect measurements and various databases in 10 and 5 µm in a good agreement with the most accurate recent experiments. In this paper we extend ab initio corrections to available line lists of ozone band intensities in wider IR range up to the bands with four vibrational quanta. About 40% of intensities were corrected in the 0 - 4122 cm−1 range for thirty cold and hot bands of the main ozone 16O3 isotopologue. Most of them, but not all, were obtained using band specific scaling factors ranging from 0.75 to 1.17 making quite significant changes in the absolute values. The full line lists containing corrected line intensities in the spectral intervals considered in the paper are provided in the Supplementary material for this work. The resulting line list is now available on the web site of the “Spectroscopy and Molecular Properties of Ozone” (SM http://smpo.univ-reims.fr ). A large part of this line list including the ab initio correction reported in this work will be used in the future HITRAN20 update.

International audience; Reliable ozone spectral data consistent over several spectral ranges are a challenge for both experiment and theory. We present ab initio calculations for strong lines that lead to consistent results from the microwave to mid-infrared regions. The results agree well with established microwave line lists and our new measurements in the fundamental and first overtone regions of ozone at 5 and 10 μm. The calculations and their agreement to within 1% with measurements provide an important step toward consistent and accurate spectroscopic ozone data. The results imply that actual databases need to be corrected by about 3% in the corresponding mid-infrared spectral intervals. Appropriate recommendations for the consistency of strong line intensities of the ozone molecule in microwave, 10 and 5 μm ranges, in HITRAN (HIgh-resolution TRANsmittance and molecular apbsorption) and GEISA (Gestion et Etude des Informations Spectroscopiques Atmosphériques) databases are suggested.I. INTRODUCTION

The room temperature absorption spectrum of water vapor highly enriched in 17O has been recorded by Cavity Ring Down Spectroscopy (CRDS) between 5850 and 6671 cm−1. Two series of recordings were performed with pressure values of 1.0 and 12.0 Torr. The investigated spectral region corresponds to the important 1.55 μm transparency window of the atmosphere where water absorption is very weak. The high sensitivity of the recordings (αmin ~ 5×10−11 cm−1) allows detecting lines with intensity spanning six orders of magnitude (1.4×10−30–3.6×10−24 cm/molecule at room temperature). The experimental list includes more than 10,300 lines. The assignments of water lines were performed using known experimental energy levels as well as calculated line lists based on the results of Partridge and Schwenke. More than 8500 lines were assigned to 9619 transitions of six water isotopologues (H216O, H217O, H218O, HD16O, HD17O and HD18O). All but four transitions of the 16O and 18O isotopologues were assigned using known experimental energy levels. More than half of the assigned H217O and HD17O transitions correspond to new (or corrected) upper energy levels. About 1000 new H217O transitions associated with upper states of the second triad and of the first hexad were identified. Most of the newly assigned HD17O transitions belong to the ν1+ν3 and 2ν2+ν3 bands. The assigned transitions allowed to newly determine or correct 20 highly excited rotational levels of the vibrational ground state of this isotopologue. Overall 791 and 266 energy levels are newly determined for H217O and HD17O, respectively. A few additional levels were corrected compared to literature values. The obtained experimental results are compared to the spectroscopic parameters provided by the HITRAN database and to the empirical energy levels recommended by an IUPAC task group.

An accurate empirical list of 57,995 transitions is constructed for natural water in the 5690–8340 cm−1 near infrared region (1.76–1.20 µm). The new list represents an updated version of the list reported in Mikhailenko et al. (2016). The spectral range is extended to lower energy and the transition frequencies benefited from a series of recent measurements by comb-assisted cavity ring down spectroscopy (CA-CRDS). The line list construction uses as starting point the variational line lists computed on the basis of the results of Schwenke and Partridge for the six most abundant water isotopologues (H2 16O, H2 18O, H2 17O, HD16O, HD18O, HD17O). Variational line positions are replaced by position values calculated from empirical rotation-vibration energy levels. The set of required empirical energy levels is improved in accuracy and enlarged, in particular for the minor isotopologues. A large number of energy levels and thus transition frequencies, relying on spectra recorded by CA-CRDS, have accuracy on the order of 10−4 cm−1. All the transitions are provided with unique vibrational labeling supported by effective Hamiltonian calculations in case of ambiguity. A detailed comparison is presented with the list of natural water included in the HITRAN2016 database and with the very recent H2 16O and H2 18O lists reported in Conway et al. (2020). The advantage of our list in terms of line position accuracy is demonstrated and illustrated by direct comparison with CRDS recordings at disposal. Intensity comparison shows a general agreement but a number of weaknesses of the most recent intensity calculations are evidenced. All the considered theoretical line lists include a few bands (e.g. 4ν2, 5ν2, ν1+2ν2 and ν1+3ν2) with intensities deviating significantly from the observations. © 2020 Elsevier Ltd E.K. Conway (Center for Astrophysics, Cambridge and University College London) is acknowledged for providing us the submitted version of Ref. [44] together with the corresponding H216O and H218O lists, prior publication. The support of the University Grenoble Alpes and CNRS (France) in the frame of International Research Project SAMIA is acknowledged. SNM activity was also partly supported in the frame of the Russian Science Foundation, grant no. 18-11-00024.

The room temperature absorption spectrum of water vapour highly enriched in 17O is recorded by cavity ring down spectroscopy (CRDS) near 1.73 µm. Two series of recordings were performed with pressure values of about 0.12 and 8.5 Torr from 5693 to 5850 cm−1. The noise equivalent absorption (αmin) of the spectra is better than 10−10 cm−1 allowing for the measurements of water lines with intensity down to 10−29 cm/molecule. A total of 1132 lines were assigned to 1220 transitions of five water isotopologues (H216O, H217O, H218O, HD16O, and HD17O). Their intensities span near five orders of magnitude from 10−29 to 10−24 cm/molecule at 296 K. The assignments were performed using known experimental energy levels as well as calculated line lists based on the results of Schwenke and Partridge. Most of the new results concern the H217O isotopologue: 483 transitions were measured while only the 27 strongest were previously known. Overall 104 levels were newly determined for H217O (64 levels), H218O (16), HD17O (23) and HD16O (1) and a few additional levels were corrected compared to the literature. The obtained results are compared to the water line list in the HITRAN2016 database, to the ExoMol energy levels and to the empirical energy levels recommended by an IUPAC task group.

The room temperature absorption spectrum of water vapour highly enriched in 17 O is studied by Comb Assisted-Cavity Ring Down Spectroscopy (CA-CRDS) near 1.4 µm. The investigated spectral region (6667–7443 cm −1 ) is a strong absorbing region corresponding to the first hexade of interacting vibrational states. As a consequence of the high sensitivity of the recordings (Noise Equivalent Absorption, α min ∼ 10 −10 cm −1 ), a series of spectra could be recorded at very low pressure (less than 0.1 Torr) allowing for accurate determination of line centres and the spectral resolution of highly blended multiplets. For instance, 85 lines of the main isotopologue located near much stronger lines are measured for the first time. The assignments were performed using known experimental energy levels as well as calculated line lists based on the results of Schwenke and Partridge. Overall, the experimental list includes 9144 water lines which were assigned to 9988 transitions of six isotopologues (H 2 16 O, H 2 17 O, H 2 18 O, HD 16 O, HD 17 O and HD 18 O). Their intensities span six orders of magnitude from 10 −27 to 10 −21 cm/molecule at 296 K. Most of the new results concern the H 2 17 O isotopologue: more than 2300 new lines were measured, 64 new levels were determined and seven levels were corrected. In the case of HD 17 O, 152 new transitions were assigned and ten levels were newly determined. The center values of non-blended lines are reported with an accuracy better than 3 MHz (10 −4 cm −1 ) which represents an improvement compared to previous determinations. The comparison to the water vapor line list provided by the recently released 2016 version of the HITRAN database reveals a number of issues.

The room temperature absorption spectrum of water vapor highly enriched in 17O has been recorded by Cavity Ring Down Spectroscopy (CRDS) between 7443 and 7921 cm−1. Three series of recordings were performed with pressure values around 0.1, 1 and 10 Torr. The frequency calibration of the present spectra benefited of the combination of the CRDS spectrometer to a self-referenced frequency comb. The resulting CRD spectrometer combines excellent frequency accuracy over a broad spectral region with a high sensitivity (Noise Equivalent Absorption, αmin∼ 10–11–10−10 cm−1). The investigated spectral region corresponds to the high energy range of the first hexade. The assignments were performed using known experimental energy levels as well as calculated line lists based on the results of Partridge and Schwenke. Overall about 4150 lines were measured and assigned to 4670 transitions of six water isotopologues (H216O, H217O, H218O, HD16O, HD17O and HD18O). Their intensities span six orders of magnitude from 10–28 to 10–22 cm/molecule. Most of the new results concern the H217O and HD17O isotopologues for which about 1600 and 400 transitions were assigned leading to the determination of 329 and 207 new energy levels, respectively. For comparison only about 300 and four transitions of H217O and HD17O were previously known in the region, respectively. By comparison to highly accurate H216O line positions available in the literature, the average accuracy on our line centers is checked to be on the order of 3 MHz (10−4 cm−1) or better for not weak well isolated lines. This small uncertainty represents a significant improvement of the line center determination of many H216O lines included in the experimental list provided as Supplementary Material .

The absorption spectrum of water vapor in “natural” isotopic abundance has been recorded at room temperature by high sensitivity Continuous Wave Cavity Ring Down Spectroscopy (CW-CRDS) between 7911 and 8337 cm −1 . The investigated region covers most of the 1.25 µm transparency window of importance for atmospheric applications. The recordings were performed with sensitivity on the order of α min ~2×10 –11 cm −1 , more than two orders of magnitude better than previous investigations by Fourier Transform Spectroscopy (FTS). Measured line intensities cover a range of seven orders of magnitude (3×10 –30 –2×10 –23 cm/molecule at room temperature). The experimental line list provided as Supplementary Material includes more than 5000 transitions. As a result of the achieved sensitivity, more than 1150 lines of the experimental list were identified as being due to ammonia present as an impurity at the 5 ppm concentration level in the water sample. Although incomplete, the obtained ammonia line list seems to be the first one in the region. More than 3193 water lines were assigned to 3560 transitions of five water isotopologues (H 2 16 O, H 2 18 O, H 2 17 O, HD 16 O and HD 18 O). The assignments were performed using known experimental energy levels and calculated spectra based on variational calculations by Schwenke and Partridge. The obtained results are compared to the most relevant previous studies by Fourier Transform Spectroscopy in the region and to the exhaustive review of rovibrational line positions and levels performed recently by an IUPAC sponsored task group. Two-hundred and sixty-six levels are newly determined and 46 are corrected by more than 0.015 cm −1 compared to those recommended by the water IUPAC task group. The overall agreement between variational and measured intensities is satisfactory. A complete empirical list of 4473 transitions incorporating all the experimental information at disposal was constructed for water in the studied region. The intensity cut-off was fixed to 1×10 –29 cm/molecule at 296 K. A detailed comparison with the line list as provided by the HITRAN database illustrates the advantages of the new list.

The rotational transitions of the HD17O water isotopologue have been assigned in a high temperature emission spectrum between 320 and 520 cm−1 of water vapor enriched by deuterium and 17O. We assigned 169 emission lines to 189 partly overlapping transitions of pure rotational and the ν2–ν2 rotational bands. A new extended set of 390 rotational energy levels for the (0 0 0) and (0 1 0) vibration states of HD17O up to J = 17 and Ka = 13 was obtained by combination of the new line transitions with those reported in previous studies. We constructed an effective rotational Hamiltonian based on the generation function approach. For this Hamiltonian the deviation between calculated and measured eigenenergies is in the order of 0.001 cm−1. We report a new calculated linelist based on our new energy level list. Our linelist supersedes the IUPAC linelist for the HD17O water isotopologue as it is based on a substantially extended set of accurate transition wavenumbers.

The RKR potentials of nine isotopologues of the carbon monoxide molecule in the ground electronic state are calculated on the basis of new values of the Dunham spectroscopic parameters Ymj up to the v = 41 vibrational level. The potential of the main isotopologue 12C16O determined at separate points is approximated by expansions in variables zD = (r−re)/re and zS = (r − re)/r. The expansion coefficients are presented.

The weak absorption spectrum of water vapor in the important 2.2 μm transparency window is investigated with very high sensitivity. Overall, about 400 absorption lines were measured by Cavity Ring Down Spectroscopy (CRDS) and Optical-Feedback-Cavity Enhanced Laser Spectroscopy (OF-CEAS) in five spectral intervals: 4248.2–4257.3, 4298.4–4302.6, 4336.8.5-4367.5, 4422.4-4441.2 and 4514.6-4533.7 cm−1. The achieved sensitivity of the recordings (noise equivalent absorption, αmin, on the order of 2×10−10 cm−1) allowed detecting transitions with intensity values down to 1×10−28 cm/molecule, more than one order of magnitude better than previous studies by Fourier Transform spectroscopy. The rovibrational assignment was performed on the basis of variational calculations and of previously determined empirical energy values. Most of the newly assigned lines correspond to transitions of the ν1, ν3 and 3ν2 bands of H217O in natural isotopic abundance. Fourteen energy levels of H217O, H218O and HD18O are newly determined. An accurate and complete spectroscopic database is constructed for natural water in the 4190–4550 cm−1 region (2.39–2.20 µm). The list includes about 4500 transitions with intensity greater than 1×10−29 cm/molecule, for the six most abundant isotopologues in natural isotopic abundance. Line positions were obtained by difference of empirical energy values determined from literature data and complemented with the present CRDS results. The list is made mostly complete by including weak transitions not yet detected, with positions calculated from empirical levels and variational intensities. The variational intensities computed by a collaboration between the University College London and the Institute of Applied Physics in Nizhny Novgorod are found to improve significantly previous results by Schwenke and Partridge. Examples of comparison of the constructed line list to CRDS spectra and to simulations based on the HITRAN2012 list illustrate the advantages of the new list. The absence of many HDO lines is identified as most important deficiency of the HITRAN2012 list in the region.

Spectroscopy and Molecular Properties of Ozone (“SM spectroscopic applications (analysis, Fourier transform spectroscopy, atmospheric optics, optical standards, spectroscopic atlases); applications to environment studies and atmospheric physics (remote sensing); data supply for specific databases; and to photochemistry (laser excitation, multiphoton processes). The system is accessible via Internet on two sites: http://smpo.iao.ru and http://smpo.univ-reims.fr .

The spectra of natural water vapor were recorded in the spectral range 6450–9400 cm−1 with a step-by-step Fourier transform spectrometer at room temperature with absorption path lengths up to 1200 m. Positions, intensities and self-broadening coefficients of about 11,000 lines were determined. This paper focuses on the intensity parameters: the lines of four isotopologues H216O, H218O, H217O and HD16O were observed and assigned; it presents a new experimental dataset in the 6450–9400 cm−1 spectral range. Obtained results were compared to the literature data. Fifty-nine new and corrected energy levels of H216O and H217O were determined from the vibration–rotation analysis of the observed lines. A brief discussion is added for self-broadening coefficients at the end of this paper.

An accurate and complete empirical spectroscopic database is constructed for natural water in the 5850–8340 cm−1 near infrared region (1.71–1.20 µm). The global list includes more than 46,500 transitions of the six most abundant isotopologues (H216O, H218O, H217O, HD16O, HD17O, HD18O) in natural isotopic abundance with intensity greater than 1×10−29 cm/molecule. All line positions were obtained by difference of empirically determined energy values. These empirical determinations are mostly based on extensive investigations of water vapor spectra by high-sensitivity CRDS complemented with literature data. In particular, the sets of energy levels of the minor isotopologues have been significantly enlarged from very recent analysis of CRDS spectra of D, 18O and 17O enriched water samples. The empirical line positions were associated to experimental intensity values from the literature obtained by FTS for the strong lines and CRDS for weaker lines. The list is made mostly complete by including a large number of weak transitions not yet detected, with empirical positions calculated from empirical levels associated with variational intensities. Air- and self-broadening coefficients and air-induced line shifts have been added to each transition using the most recent version of the algorithm used for the HITRAN and GEISA databases. Examples of comparison of CRDS spectra to simulations based on the HITRAN2012 list illustrate the advantages of our database. The relative merit of experimental and variational line intensities is discussed. A separate line list combining empirical line positions and variational intensities is provided. Future improvements from combination of experimental and variational intensities are suggested.

The GEISA database (Gestion et Etude des Informations Spectroscopiques Atmosphériques: Management and Study of Atmospheric Spectroscopic Information) has been developed and maintained by the ARA/ABC(t) group at LMD since 1974. GEISA is constantly evolving, taking into account the best available spectroscopic data. This paper presents the 2015 release of GEISA (GEISA-2015), which updates the last edition of 2011 and celebrates the 40th anniversary of the database. Significant updates and additions have been implemented in the three following independent databases of GEISA. The “line parameters database” contains 52 molecular species (118 isotopologues) and transitions in the spectral range from 10−6 to 35,877.031 cm−1, representing 5,067,351 entries, against 3,794,297 in GEISA-2011. Among the previously existing molecules, 20 molecular species have been updated. A new molecule (SO3) has been added. HDO, isotopologue of H2O, is now identified as an independent molecular species. Seven new isotopologues have been added to the GEISA-2015 database. The “cross section sub-database” has been enriched by the addition of 43 new molecular species in its infrared part, 4 molecules (ethane, propane, acetone, acetonitrile) are also updated; they represent 3% of the update. A new section is added, in the near-infrared spectral region, involving 7 molecular species: CH3CN, CH3I, CH3O2, H2CO, HO2, HONO, NH3. The “microphysical and optical properties of atmospheric aerosols sub-database” has been updated for the first time since 2003. It contains more than 40 species originating from NCAR and 20 from the ARIA archive of Oxford University. As for the previous versions, this new release of GEISA and associated management software facilities are implemented and freely accessible on the AERIS/ESPRI atmospheric chemistry data center website., SCOPUS: ar.j, info:eu-repo/semantics/published

Using a Fourier-transform spectrometer, we have measured the absorption spectrum of H218O vapor in the range 13400–14460 cm−1 at room temperature with a resolution of 0.03 cm−1 and a threshold sensitivity in absorption of 10−6 cm−1. With a multipass cell, the volume of which was 3 L and the base of which was 25 cm, a length of the absorbing layer of 10 m has been achieved. A high signal-to-noise ratio, on the order of 1000, has allowed us to detect about 700 lines of the H218O molecule, the intensities of which were as low as 10−25 cm/molecule, at 296 K. The observed lines have been attributed to eleven vibrational-rotational bands of the molecule.

High-resolution water vapor absorption spectra have been measured at room temperature in the 8800-11,600cm -1 spectral region. They were obtained using the mobile BRUKER IFS 120M Fourier transform spectrometer (FTS) from ULB-SCQP coupled to the 50m base long multiple reflection White type cell in GSMA laboratory. The absorption path was 600m and different H 2O/HDO/D 2O mixtures were used. Measurements of line positions, intensities and self-broadening coefficients were performed for the HD 16O isotopologue. 6464 rovibrational assignment of the observed lines was made on the basis of global variational predictions and allowed the identification of new energy levels. 3ν 3, 2ν 1+ν 3, 3ν 1+ν 2, ν 1+2ν 3 and 2ν 2+2ν 3 are the five strongest bands. The present paper provides a complementary data set on water vapor for atmospheric and astrophysical applications. © 2012 Elsevier Ltd., SCOPUS: ar.j, info:eu-repo/semantics/published

The spectra of water vapor enriched by 18O were recorded in the 1000–2300 cm−1 spectral range, which corresponds to the spectral region studied by IASI instrument (Infrared Atmospheric Sounding Spectrometer) instrument. The spectra were recorded by a step by step Fourier Transform Spectrometer (FTS) at room temperature with absorption path lengths up to 36 m. Positions, intensities and self broadening coefficients of about 1800 lines of H218O and 900 of HD18O were analyzed and all the transitions were assigned. This paper focuses on lines intensities and comparisons with data from literature are presented. An average difference of 10% with HITRAN2008 database H218O line intensities is found with a maximum discrepancy of about 25% for the ν1–ν2 band.

The absorption spectrum of water vapor enriched by deuterium and oxygen-18 is analyzed in the 6000–9200 cm−1 region. The spectrum has been recorded at room temperature with a Bruker IFS 120 h Fourier transform spectrometer. More than 14,000 absorption lines were measured in the recorded spectrum. The vibration–rotation assignments were performed on the basis of previously published experimental energies and of variational calculations. Nine water species (H216O, HD16O, D216O, H218O, HD18O, D218O, H217O, HD17O and D217O) were found to contribute to the observed absorption. More than 3600 lines of 19 vibrational bands of D218O and about 4700 lines of 16 bands of HD18O with J as high as 19 and Ka as high as 11 were assigned. The main part of the HD18O and D218O lines and all lines of HD17O and D217O were observed in the laboratory for the first time. The obtained vibration–rotation energy levels are compared with previous experimental studies and the results of variational calculations.

High-resolution Fourier-transform spectra of water samples enriched by deuterium and oxygen-18 at room temperature are analyzed in the range 969–2148 cm−1. Line positions of about 2470 transitions up to Jmax = 22 and Ka max = 12 of the ν2 bands of the HD18O and D 2 18 O molecules are reported. This has allowed the determination of extended sets of rotational energies of the (0 0 0) and (0 1 0) vibrational states for both molecules. The generation function model of an effective rotational Hamiltonian was used in the data reduction to account for the strong centrifugal distortion of the rotational levels. Values of effective Hamiltonian parameters have been determined. The RMS standard deviations of the least-squares fits of the energy levels were 2.4 × 10−4 cm−1 for 293 energy levels of the ground state and 3.2 × 10−4 cm−1 for 281 energy levels of the (010) state of D 2 18 O , and 2.6 × 10−4 cm−1 for 227 energy levels of the ground state and 4.2 × 10−4 cm−1 for 246 energy levels of the (0 1 0) state of HD18O. Comparisons of obtained data with the theoretical predictions as well as with other observations are presented.

A methane spectral line list for the 5550–6236 cm −1 range with the intensity cut off 4×10 −26 cm/molecule at 296 K is presented. The line list is based on new extensive measurements of methane spectral line parameters performed at different temperatures and pressures of methane and buffer gases N 2 , O 2 and air. This spectral line list is prepared in HITRAN-2008 format and contains the following spectral line parameters of about 11,000 lines: position, intensity, energy for lower state (where possible), air-broadening and air-shifting coefficients, exponent of temperature dependence of air-broadening coefficient and self-broadening coefficient.

This is the second of a series of articles reporting critically evaluated rotational-vibrational line positions, transition intensities, pressure dependences, and energy levels, with associated critically reviewed assignments and uncertainties, for all the main isotopologues of water. This article presents Preprint submitted to Journal of Quantitative Spectroscopy & Radiative Transfer10th June 2010 energy levels and line positions of the following singly deuterated isotopologues of water: HD16O, HD17O, and HD18O. The MARVEL (Measured Active Rotational-Vibrational Energy Levels) procedure is used to determine the levels, the lines, and their self-consistent uncertainties for the spectral regions 0–22 708, 0–1 674, and 0–12 105 cm−1 for HD16O, HD17O, and HD18O, respectively. For HD16O, 54 740 transitions were analyzed from 76 sources, the lines come from spectra recorded both at room temperature and from hot samples. These lines correspond to 36 690 distinct assignments and 8 818 energy levels. For HD17O, only 485 transitions could be analyzed from 3 sources; the lines correspond to 162 MARVEL energy levels. For HD18O, 8 729 transitions were analyzed from 11 sources and these lines correspond to 1 860 energy levels. The energy levels are checked against ones determined from accurate variational nuclear motion computations employing exact kinetic energy operators. This comparison shows that the measured transitions account for about 86 % of the anticipated absorbance of HD16O at 296 K and that the transitions predicted by the MARVEL energy levels account for essentially all the remaining absorbance. The extensive list of MARVEL lines and levels obtained are given in the Supplementary Material of this article, as well as in a distributed information system applied to water, W@DIS, where they can easily be retrieved. In addition, the transition and energy level information for H2 17O and H2 18O, given in the first paper of this series [J. Quant. Spectr. Rad. Transfer 110 (2009) 573-596], has been updated. Key words: Water vapor, transition wavenumbers, atmospheric physics, energy levels, MARVEL, information system, database, W@DIS, infrared spectra, microwave spectra, HD16O, HD17O, HD18O

Self-pressure-induced, as well as argon- and nitrogen-induced, broadening γ and shifting δ coefficients of vibrational-rotational lines of the water molecule have been calculated. The asymptotic behavior of the coefficients γ and δ at J → 42 and Ka → J has been studied. For the calculation of the parameters γ and δ, we used the wave functions obtained from the analysis of highly excited rotational states of the H2O molecule with the maximal ever observed values of rotational quantum numbers Jmax = 42, Kamax = 32. Rotational states were analyzed in the method of effective Hamiltonians using generating functions for the first eight vibrational states of the molecule.

The absorption spectra of the 12CH4 and 13CH4 molecules have been recorded and assigned in the 5560–6200 cm−1 region. The effects of isotopic substitution for 12C by 13C on the methane vibrational energy levels have been calculated from an ab initio potential energy surface and compared with experiment. Comparison of the results obtained for two isotopic species allows us to confirm the vibrational assignment for the strongest bands of 12CH4 in this region. Good agreement of ab initio calculations with observed energy levels has been demonstrated. A list of the assigned 13CH4 lines valuable in atmospheric applications is reported.

Water vapor infrared spectra have been measured using the Bruker IFS 120 HR Fourier transform spectrometer at the Physikalisch-Chemisches Institut of the Justus-Liebig-Universitat Giessen. Spectra were recorded at pressure-broadening-limited resolution and at room temperature in the range of 1900–6600 cm−1. The use of fully evacuated transfer optics and a White-type multireflection cell made it possible to obtain pressure×pathlength products up to 31.27 mbar×288.5 m. These spectra have previously been used to determine experimental values of rovibrational line positions and upper energy levels of the 2ν2, ν1, and ν3 bands [Mikhailenko SN, Tyuterev VlG, Keppler KA, Winnewisser BP, Winnewisser M, Mellau G, et. al. The 2ν2 band of water: analysis of new FTS measurements and high-Ka transitions and energy levels. J Mol Spectrosc 1997;184: 330–49] and of the 3ν2, ν1+ν2, and ν2+ν3 bands [Mikhailenko SN, Tyuterev VlG, Starikov VI, Albert KK, Winnewisser BP, Winnewisser M, et al. Water spectra in the region 4200–6250 cm−1, extended analysis of ν1+ν2, ν2+ν3, and 3ν2 bands and confirmation of highly excited states from flame spectra and from atmospheric long-path observations. J. Mol. Spectrosc. 2002; 213: 91–121]. This work presents the intensities of 3769 lines for the weak and medium transitions in the spectral range indicated. These data provide an independent source of experimental information which is complementary to intensity data available in the literature and can thus help to evaluate experimental errors and the reliability of these spectral line parameters.

New high-resolution water vapor absorption spectra were obtained at room temperature in the 4200–6600 cm−1 spectral region by combining Fourier transform spectrometers (FTS) with single and multiple reflection cells. With absorption paths from 0.3 to 1800 m in pure and air diluted water vapor, accurate measurements of about 10400 lines in an intensity range from 10−29 to 10−19 cm/molecule have been performed. Positions, intensities, self- and air-broadening coefficients and air-induced shifts were determined for the H216O, H217O, H218O and HDO isotopologues. The rovibrational assignment of the observed lines was performed with the use of global variational predictions and allowed the identification of several new energy levels. One major contribution of this work consists of the identification of 3280 new weak lines. A very close agreement between the new measured parameters and those listed in the database is reported as well as between the observations and the most recent variational calculations for the positions and the intensities. The present parameters provide an extended and homogeneous data set for water vapor, which is shown to significantly improve the databases for atmospheric applications, especially in the transmission windows on both sides of the band centered at 5400 cm−1.

The updated methane spectral line list GOSAT-2014 for the 5550–6240 cm −1 region with the intensity cutoff of 5×10 –25 cm/molecule at 296 K is presented. The line list is based on the extensive measurements of the methane spectral line parameters performed at different temperatures and pressures of methane without and with buffer gases N 2 , O 2 and air. It contains the following spectral line parameters of about 12150 transitions: line position, line intensity, energy of lower state, air-induced and self-pressure-induced broadening and shift coefficients and temperature exponent of air-broadening coefficient. The accuracy of the line positions and intensities are considerably improved in comparison with the previous version GOSAT-2009. The improvement of the line list is done mainly due to the involving to the line position and intensity retrieval of six new spectra recorded with short path way (8.75 cm). The air-broadening and air-shift coefficients for the J -manifolds of the 2ν 3 (F 2 ) band are refitted using the new more precise values of the line positions and intensities. The line assignment is considerably extended. The lower state J -value was assigned to 6397 lines representing 94.4% of integrated intensity of the considering wavenumber region. The complete assignment was done for 2750 lines.

The far-infrared and middle-infrared emission spectra of deuterated water vapour were measured at temperatures 1370, 1520, and 1940 K in the ranges 320–860 and 1750–3400 cm−1. The measurements were performed in an alumina cell with an effective length of hot gas of about 50 cm. More than 3550 new measured lines for the D216O molecule corresponding to transitions from highly excited rotational levels of the (0 2 0), (1 0 0), and (0 0 1) vibrational states are reported. These new lines correspond to rotational states with higher values of the rotational quantum numbers compared to previously published determinations: Jmax = 29 and Ka(max) = 22 for the (0 2 0) state, Jmax = 29 and Ka(max) = 25 for the (1 0 0) state, and Jmax = 30 and Ka(max) = 23 for the (0 0 1) state. The extended set of 1987 experimental rotational energy levels for the (0 2 0), (1 0 0), and (0 0 1) vibration states including all previously available data has been determined. For the data reduction we used the generating function model. The root mean square (RMS) deviation between observed and calculated values is 0.004 cm−1 for 1952 rovibrational levels of all three vibration states. A comparison of the observed energy levels with the best available values from the literature and with the global predictions from molecular electronic potential energy surfaces of water isotopic species [H. Partridge, D.W. Schwenke, J. Chem. Phys. 106 (1997) 4618] is discussed. The latter confirms a good consistency of mass-dependent DBOC corrections in the PS potential function with new experimental rovibrational data.

The absorption spectrum of natural water vapour around 1.5 μm has been recorded with a typical sensitivity of 5 × 10−10 cm−1 by using a CW-cavity ring down spectroscopy set up based on fibred DFB lasers. A series of 31 DFB lasers has allowed a full coverage of the 6130.8–6748.5 cm−1 (1.63–1.48 μm) region corresponding to the H transparency band of the atmosphere. The line parameters (wavenumber and intensity) of a total of 5190 lines, including 4247 lines of water vapor, were derived by a one by one fit of the lines to a Voigt profile. Different isotopologues of water (H216O, H218O, H217O, and HD16O) present in natural abundance in the sample contribute to the spectrum. For the main isotopologue, H216O, 2130 lines were measured with line intensities as weak as 10−29 cm/molecule while only 926 lines (including a proportion of 30% inaccurate calculated lines) with a minimum intensity of 3 × 10−27 cm/molecule are provided by the HITRAN and GEISA databases. Our comparison in the whole 5750–7965 cm−1 region, has also evidenced that an error in the process of conversion of the intensity units from cm−2/atm to cm−1/(molecule × cm−2) at 296 K, has led to H216O line intensities values listed in the HITRAN-2000 database, systematically 8 % below the original FTS values. The rovibrational assignment was performed on the basis of the ab initio calculations by Schwenke and Partridge with a subsequent refinement and validation using the Ritz combination principle together with all previously measured water transitions relevant to this study. This procedure allowed determining 172, 139, 71, and 115 new energy levels for the H216O, H218O, H217O, and HD16O isotopologues, respectively. The results are compared with the available databases and discussed in regard of previous investigations by Fourier transform spectroscopy. The spectrum analysis has showed that most of the transitions which cannot be assigned to water are very weak and are due to impurities such as carbon dioxide and ammonia, leaving only about 3% of the observed transitions unassigned. The interest of a detailed knowledge of water absorption for trace detectors developed in the 1.5 μm range is underlined: for instance HDO contributes significantly to the considered spectrum while no HDO line parameters are provided by the HITRAN database.

The far-infrared emission spectra of deuterated water vapour were measured at different temperatures (1370, 1520, and 1950 K) in the range 320–860 cm−1 at a resolution of 0.0055 cm−1. The measurements were performed in an alumina cell with an effective length of hot gas of about 50 cm. More than 1150 new measured lines for the D216O molecule corresponding to transitions between highly excited rotational levels of the (0 0 0) and (0 1 0) vibrational states are reported. These new lines correspond to rotational states with higher values of the rotational quantum numbers compared to previously published determinations: Jmax=26 and K a (max) =26 for the (0 0 0) ← (0 0 0) band, Jmax=25 and K a (max) =25 for the (0 1 0) ← (0 1 0) band, and Jmax=26 and K a (max) =18 for the (0 1 0) ← (0 0 0) band. The estimated accuracy of the measured line positions is 0.0005 cm−1. To our knowledge no experimentally measured rotational transitions for D216O within an excited vibrational state have been available in the literature so far. An extended set of experimental rotational energy levels for (0 0 0) and (0 1 0) vibration states including all previously available data has been determined. For the data reduction we used the generating function model. The root mean square (RMS) deviation between observed and calculated values is 0.0012 cm−1 for 692 rotational levels of the (0 0 0) state and 0.0010 cm−1 for 639 rotational levels of the (0 1 0) vibrational state. A comparison of the observed energy levels with the best available values from the literature and with the global predictions from molecular electronic potential energy surface [J. Chem. Phys. 106 (1997) 4618] for the (0 0 0) and (0 1 0) states is discussed.

The far-infrared emission spectrum of water vapour have been recorded at temperature 1370 K in the range 400–850 cm −1 at resolutions (FWHM) 0.0055 cm −1 . The measurements have been done in a fused quartz cell with an effective length of hot gas of about 60 cm. Among about 200 lines assigned to the H 2 18 O isotopomer 106 lines have not been reported in previous studies. These newly measured lines correspond to higher values of rotational quantum numbers compared to previous determinations: Jmax=18 and K a ( max ) =17 for the (0 0 0)←(0 0 0) band and Jmax=15 and K a ( max ) =11 for the (0 1 0)←(0 1 0) band. Estimated accuracy of line position measurements is 0.0005 cm −1 . To our knowledge rotational transitions within an excited bending state have been measured for the first time for H218O. An extended set of experimental rotational energy levels for (0 0 0) and (0 1 0) vibration states including all previously available data has been determined. A data reduction has been done using the generating function model. The root mean square (RMS) deviation between observed and calculated values is 0.0009 cm −1 for 305 rotational levels of the (0 0 0) state and 0.0007 cm −1 for 198 rotational levels of the (0 1 0) state. A comparison of the observed data with the best available predictions from the molecular electronic potential energy surface [J. Chem. Phys. 106 (1997) 4618] and isotopic effects for rotational levels of (0 0 0) and (0 1 0) states are discussed.

The 2900–3400 cm −1 spectral range is revisited for an accurate determination of line positions and line intensities of the 3ν 3 , ν 1 +2ν 3 , 2ν 1 +ν 3 , and 3ν 1 bands of ozone. The fit on 4520 rotational energy levels of (012), (111), (210), (130), (003), (102), (201), and (300) vibrational states determined from observed transitions of cold and hot bands in the 2400–3400 cm −1 region with J max =65 and K a max =20 gives a r.m.s. =7×10 −4 cm −1 and provides a satisfactory agreement between calculated and observed line positions (dimensionless standard deviation is χ=1.44). The set of 2580 line intensities of 7 rovibrational bands has been measured and fitted with a r.m.s. =6.9% (χ=1.2), leading to the determination of transition moment parameters for these bands. Using these parameters we have obtained more precise estimation for the integrated band intensities S(3ν 3 )=1.41×10 −19 , S(ν 1 +2ν 3 )=1.28×10 −20 , S(2ν 1 +ν 3 )=7.91×10 −21 , S(3ν 1 )=4.72×10 −22 cm −1 /mol cm −2 at 296 K, with a cutoff 2×10 −26 cm −1 /mol cm −2 . The interactions of the tetrad (003)/(102)/(201)/(300) with the (130) state and the tetrad (040)/(012)/(111)/(210) are studied.

The isotopically invariant Dunham parameters U mj , Δ mj H and Δ mj Cl were determined by simultaneously fitting the line centers of vibration-rotation transitions of six isotopic HCl forms in the ground electronic state. Fitting included relations between U mj values. The parameters of the isotopically invariant potential of HCl were determined using independent U m0 and U m1 values. The contributions to the vibrational terms of H35Cl caused by violation of the Born-Oppenheimer approximation were calculated.

Water vapor infrared spectra have been recorded at room temperature in the range 4200–6250 cm−1 at resolutions (FWHM) between 0.0053 and 0.0080 cm−1. The use of a White-type multireflection cell made large pressure × pathlength products possible up to 31.27 mbar×288.5 m. The high signal-to-noise ratio allowed us to observe lines with intensities as small as 10−26 cm−1/molecule cm−2 at T=296 K. Among about 5100 recorded water lines, about half of which are reported for the first time, 2351 lines have been assigned to the second triad of H216O (bands ν1+ν2, ν2+ν3, and 3ν2). This has allowed the determination of line positions and corresponding upper rovibrational states with considerably improved accuracy. The assignments of certain highly excited states have been confirmed by the analysis of flame spectra and hot emission spectra. New values of effective Hamiltonian parameters for the upper states {(110), (030), (011)} have been determined. The generating function model was used in the data reduction to account for the anomalously strong centrifugal distortion of the rovibrational levels and resonance interactions. The RMS standard deviation of the least-squares fit of the assigned H2O data was 5×10−3 cm−1 for line positions and 7×10−3 cm−1 for energy levels up to Jmax=20 and Ka(max)=13. Particular attention was paid to water lines in the transparency window 4200–5000 cm−1, in which existing databases are not sufficient. In this region, 1395 lines of four isotopic species of water have been recorded and over 900 accurate line positions of nine bands of H216O (ν1, ν3, 2ν2, ν1+ν2, ν2+ν3, 3ν2, 4ν2−ν2, 2ν2+ν3−ν2, ν1+2ν2−ν2) are reported in this range. A comparison of laboratory spectra with long path atmospheric spectra (20 km slant path in the mountains) in this region shows that many lines missing from available spectroscopic compilations (or considerably shifted compared to observations) are important for a proper interpretation of atmospheric observations. A comparison of the observed data with the best available predictions from the molecular electronic potential energy surface is discussed.

An empirical line list has been constructed for “natural” water vapor at 296 K in the 5850–7920 cm −1 region. It was obtained by gathering separate line lists recently published on the basis of spectra recorded by high sensitivity Continuous Wave Cavity Ring Down Spectroscopy (CW-CRDS) of natural water, complemented with literature data for the strongest lines. The list includes 38,318 transitions of four major water isotopologues (H 2 16 O, H 2 18 O, H 2 17 O and HD 16 O) with an intensity cut-off of 1×10 −29 cm/molecule at 296 K. The list is made mostly complete over the whole spectral region by including a large number of weak lines with positions calculated using experimentally determined energy levels and intensities obtained from variational calculations. In addition, we provide HD 18 O and HD 17 O lists in the same region for transitions with intensities larger than 1×10 −29 cm/molecule. The HD 18 O and HD 17 O lists (1972 lines in total) were obtained using empirical energy levels available in the literature and variational intensities. The global list (40,290 transitions) for water including the contribution of the six major isotopologues will be adopted for the next edition of the GEISA database in the region. The advantages and drawbacks of our list are discussed in comparison with the list provided for the same region in the 2012 edition of the HITRAN database. The direct comparison of the CRDS spectra to simulations based on the HITRAN list has revealed some insufficiencies which could easily be corrected: missing HDO lines, duplicated lines, inaccurate line positions or line intensities from variational calculations.

The application of the generating-function approach in the Borel-type summation method leads to a new kind of generating function for an effective rotational Hamiltonian of non-rigid X2Y-type molecules. These functions are based on the incomplete gamma function Γ(a,x). The integrand exponent parameter a determines the asymptotic behaviour of the calculated energy levels. A new type of generating function was tested in the calculations of rotational energies of the (040) vibrational state of H2O and the ground state of CH2 molecules.

The and bands of ozone, which occur in the region, have been observed for the first time using a Fourier transform spectrometer, operating at resolution and with a large pathlength pressure product . The assignment of rotation-vibration transitions has been done for J up to 35 and Ka up to 12, for the band and up to J = 40 and Ka = 2 for the band respectively. The effective Hamiltonian used in calculations accounts for the first-order Coriolis coupling between these two bands. In addition, as the levels corresponding to Ka = 5 are perturbed, it was necessary to account for anharmonic resonance with the (321) state. Also, to correctly reproduce the levels of (015) with Ka = 8,9,10 it has been necessary to include a Coriolis coupling with (080) state in the model. In this way, we have obtained a very satisfactory r.m.s. deviation of , near the experimental accuracy. Rovibrational line intensities of and bands were measured and the value of the principal transition moment constants have been recovered. Finally a complete list of line positions and intensities was calculated leading to the integrated band intensity of /molecule for the band and /molecule for the band at 296 K with a cut-off of .

A new theoretical model of an effective Hamiltonian for nonrigid H2X-type molecules, based on the generating function approach, is applied to the experimental energy levels (R.A. Toth, Appl. Opt. 33 (1994) 4851–4867) of the first hexad of interacting states of H2O. The results of simultaneous fitting rotational levels of the six vibrational states of H2O up to J = 8, up to J = 10, and up to J = 15 are discussed. The experimental energy levels for J ≤ 8, for J ≤ 10, and for J ≤ 15 are fitted with an average discrepancy σ = 3.9 × 10−3 cm−1, σ = 6.1 × 10−3 cm−1 and σ = 10.5 × 10−3 cm−1, respectively. In the final fitting of 749 energy levels the additional new experimental energies were used and in this case σ = 13.6 × 10−3 cm−1. The influence of interaction between the first and second hexads of H2O molecule is also discussed.

Hot bands nu1 + 3nu2 - nu2 and 3nu2 + nu3 - nu2 of 16O3 in the region 2300-2600 cm-1 and the cold band 3nu2 + nu3 in the region 3050-3110 cm-1, corresponding to the v2 = 3 dyad {(130), (031)}, have been observed for the first time, using the Fourier Transform Spectrometer (FTS) at Reims and the usual experimental setup providing a large product pressure x path length, p x l. Three hundred sixty-five rovibration energy levels of the upper states were obtained with J and Ka up to 46 and 9, respectively. The fit of these data gives a r.m.s. deviation of 1.93 x 10(-3) cm-1. The v2 dependence of the rotational parameters A, B, and C for the (1v20) and (0v21) states is discussed. Copyright 1998 Academic Press. Copyright 1998Academic Press

The vibration–rotation energy levels of the (131) state of ozone have been obtained, covering the whole range of J up to 33 and K a up to 9, from the analysis of the hot band, observed for the first time ν 1 + 3ν 2 + ν 3 − ν 2 in the 3400 cm −1 region. The assignments have been confirmed by the analysis of the cold band ν 1 + 3ν 2 + ν 3 recorded in the 4100 cm −1 region. This enabled us also to derive the transition moment ϕ z 000–131 = 1.8 × 10 −4 D. The analysis has been performed using single state Watson's Hamiltonian where the 164 levels are fitted with 10 parameters with a r.m.s. deviation of 1.9 × 10 −3 cm −1 , near the experimental accuracy. Note that the analysis involving simultaneously three interacting states of the Triad {(230), (131), (032)} has also been performed which however did not result in an improvement of the r.m.s. deviation of the fit. This work allows us to observe a quasilinear variation of A (1 v 2 1), B (1 v 2 1) + C (1 v 2 1) and Δ K (1 v 2 1) with respect to v 2 . This result is of first importance to derive band centers of perturbing levels involving v 2 ≥ 3.