Search

• The HITEMP database has been expanded to include a total of seven molecules for high-temperature applications. • NO 2 and N 2 O have been incorporated into the HITEMP database. • The NO line list in HITEMP has also been updated and expanded. • Validation of ab initio and semi-empirical line lists against experimental measurements was performed, adjustments were made where necessary. This work describes the update of NO along with the incorporation of NO 2 and N 2 O to the HITEMP database. Where appropriate, the HITRAN line lists for the same molecules have also been updated. This work brings the current number of molecules provided by HITEMP to seven. The initial line lists originating from ab initio and semi-empirical methods for each molecule have been carefully validated against available observations and, where necessary, adjustments have been made to match observations. We anticipate this work will be applied to a variety of high-temperature environments including astronomical applications, combustion monitoring, and non-local thermodynamic equilibrium conditions. [ABSTRACT FROM AUTHOR]

We describe a new, online interface to the HITRAN database that overcomes the many limitations of the existing, 160-character fixed-width, text based format (the “.par” files mostly distributed through an FTP site until now). The interface, called HITRAN online , accesses a relational database [JQSRT 2013:130, 57-61] in which the spectroscopic data are stored in a flexible, extensible and structured format. This allows an arbitrary number of different parameters for each transition to be stored so that HITRAN can represent, for example, non-Voigt line shape profiles as well as parameters representing broadening by species other than “air” and “self”. The online interface provides many ways of visualizing data as part of querying the database and allows users to create and save their own output formats to suit their own needs. A bibliography file produced with each data file provides citations and notes to the original data sources to make it easier for users to credit data providers. Once registered with the HITRAN online service, users also have (private) access to thier own search history which summarizes and can repeat queries. [ABSTRACT FROM AUTHOR]

To increase the potential for use of the HITRAN database in astronomy, experimental and theoretical line-broadening coefficients, line shifts and temperature-dependence exponents of molecules of planetary interest broadened by H 2 , He, and CO 2 have been assembled from available peer-reviewed sources. The collected data were used to create semi-empirical models so that every HITRAN line of the studied molecules has corresponding parameters. Since H 2 and He are major constituents in the atmospheres of gas giants, and CO 2 predominates in atmospheres of some rocky planets with volcanic activity, these spectroscopic data are important for remote sensing studies of planetary atmospheres. In this paper we make the first step in assembling complete sets of these parameters, thereby creating datasets for SO 2 , NH 3 , HF, HCl, OCS and C 2 H 2 . [ABSTRACT FROM AUTHOR]

Abstract: Accurate spectroscopic parameters for the hydrogen halides, namely HF, HCl, HBr, and HI, together with their deuterated isotopologues, are crucial for the quantitative study of terrestrial and planetary atmospheres, astrophysical objects, and chemical lasers. A thorough evaluation of all the hydrogen halide line parameters in previous HITRAN editions has been carried out. A new set of line lists was generated for the HITRAN2012 edition using methods described here. In total, 131,798 entries were generated for numerous pure-rotational and ro-vibrational transitions (fundamental, overtone, and hot bands) for hydrogen halides and their deuterated species in a standard HITRAN 160-character format. Data for the deuterated isotopologues have been entered into HITRAN for the first time. The calculations employ the recently developed semi-empirical dipole moment functions [Li G, et al. J Quant Spectrosc Radiat Transfer 2013;121:78–90] and very accurate analytical potential energy functions and associated functions characterizing Born–Oppenheimer breakdown effects. Line-shape parameters have also been updated using the most recent available experimental and theoretical studies. Comparison with the previous HITRAN compilation has shown significant improvements. [Copyright &y& Elsevier]

Abstract: A new format for the HITRAN database is proposed. By storing the line-transition data in a number of linked tables described by a relational database schema, it is possible to overcome the limitations of the existing format, which have become increasingly apparent over the last few years as new and more varied data are being used by radiative-transfer models. Although the database in the new format can be searched using the well-established Structured Query Language (SQL), a web service, HITRANonline, has been deployed to allow users to make most common queries of the database using a graphical user interface in a web page. The advantages of the relational form of the database to ensuring data integrity and consistency are explored, and the compatibility of the online interface with the emerging standards of the Virtual Atomic and Molecular Data Centre (VAMDC) project is discussed. In particular, the ability to access HITRAN data using a standard query language from other websites, command line tools and from within computer programs is described. [Copyright &y& Elsevier]

Highlights: [•] Very high sensitivity CW-Cavity Ring Down spectroscopy of nitrogen near 1.44μm. [•] A record sensitivity of αmin ∼6×10−13 cm−1 is achieved by averaging CW-CRDS spectra. [•] Two electric quadrupole transitions of the 3-0 band of 14N2 are detected. [•] The measured lines are among the weakest ever detected in the laboratory. [•] Good agreement with theoretical values for the line positions and line intensities. [ABSTRACT FROM AUTHOR]

Abstract: Knowledge of the infrared transition moments of hydrogen halides, namely HF, HCl, HBr, and HI, is essential for atmospheric, astrophysical, and laser applications. Recently, a new polynomial empirical dipole moment function (DMF) for HCl has been constructed using an efficient approach that involves a direct fit of experimental ro-vibrational intensities [Li et al. J Quant Spectrosc Radiat Transfer 2011;112:1543–50]. In the present study, this method was extended to the use of Padé approximation representations of the DMF and applied to all four hydrogen halides. To carry out the fits, the best available experimental data were collected and critically evaluated. Combining dipole moment functions with the wavefunctions obtained from highly-accurate empirical potential energy curves, line intensities were computed numerically for numerous ro-vibrational bands, and compared with the experimental values and with intensities calculated using the most recent ab initio dipole moment functions. Results obtained in this work form basis for calculating intensities of spectral lines of hydrogen halides and their isotopologues in the HITRAN 2012 database. [Copyright &y& Elsevier]

Abstract: Until recently the B (b 1Σg + (v=1)−X 3Σg − (v=0)) and γ (b 1Σg + (v=2)−X 3Σg − (v=0)) bands of oxygen in the visible region had not been used extensively in satellite remote sensing of the atmosphere. These bands roughly cover the regions around 14,527 and 15,904cm−1, respectively (0.69 and 0.63μm). However, these bands (in particular the B-band) are now being increasingly considered for future satellite missions. In this light, it is important to make sure that the reference spectroscopic parameters allow accurate retrieval of important physical characteristics from the atmospheric spectra. The spectroscopic parameters currently given for these bands in the HITRAN2008 spectroscopic database were tested against high-resolution atmospheric spectra measured with solar-pointing Fourier transform spectrometers at Park Falls, Wisconsin (B-band) and Kitt Peak, Arizona (γ-band). It was found that the current HITRAN parameters cannot produce satisfactory fits of the observed spectra. In order to improve the database we have collected the best available measured line positions that involve the b 1Σg + (v=1 and v=2) states for the three most abundant isotopologues of oxygen and performed a combined fit to obtain a consistent set of spectroscopic constants. These constants were then used to calculate the line positions. A careful review of the available intensity and line-shape measurements was also carried out, and new parameters were derived based on that review. In particular, line shift parameters, that were not previously available, were introduced. The new data have been validated using the high-resolution atmospheric spectra measured with the Fourier transform spectrometers at Park Falls, Wisconsin (B-band) and Kitt Peak, Arizona (γ-band) and have yielded substantial improvement. In addition, we report the first direct observation and analysis of the 16O18O lines in the γ-band. [Copyright &y& Elsevier]

Abstract: Electric quadrupole transitions in the band of 16O2 near 1.27μm are reported for the first time. They were first detected in atmospheric solar spectra acquired with a ground-based Fourier transform spectrometer (FTS) in Park Falls, WI. Subsequently high-sensitivity CW—cavity ring down spectroscopy (CW-CRDS) experiments were carried out at Grenoble University in the 7717–7917cm−1 region in order to provide quantitative intensity information for the electric quadrupole transitions. Measured intensities were used as input data for the calculation of the complete list of electric quadrupole transitions with ΔJ=±2, ±1 and 0. The calculation was carried out for the intermediate coupling case and assuming that these transitions are possible only through mixing of the Ω=0 component of the ground electronic state and state induced by spin–orbit coupling. The calculated line list agrees well with experimental measurements and was used to improve the residuals of the fitted solar atmospheric spectrum. Emission probability for the electric quadrupole band was determined to be (1.02±0.10)×10−6 s−1. [Copyright &y& Elsevier]

Abstract: The current edition of the HITRAN compilation employed a sophisticated algorithm for combining measurements available for the air-broadened half-widths of water-vapor absorption lines with theoretical values. Nevertheless, some of the values in the HITRAN database were found to be far from ideal, due to large dispersions that still exist in the experimental or theoretical methods. Therefore, new criteria were developed for introducing the best available air-broadened half-widths into HITRAN, based on physical principles and statistics. This update concerns the three most abundant isotopologues of water, with the values for H2 17O and H2 18O being the ones from analogous transitions of the principal isotopologues. The new parameters have been tested in different remote-sensing applications and improved constituent profiles were obtained. In total, air-broadened half-width values were updated for 11,787 transitions of water vapor in the HITRAN database (6789 for H2 16O, 2906 for H2 17O, and 2092 for H2 18O). Some additional updates to the water-vapor line list are also presented. The resultant file (01_hit06.par) was uploaded to the HITRAN website (http://www.cfa.harvard.edu/hitran/) in September 2006. [Copyright &y& Elsevier]

This paper outlines the major updates of the line-shape parameters that were performed for the nitrous oxide (N 2 O) and carbon monoxide (CO) molecules listed in the HITRAN2020 database. We reviewed the collected measurements for the air- and self-broadened N 2 O and CO spectra to determine proper values for the spectroscopic parameters. Careful comparisons of broadening parameters using the Voigt and speed-dependent Voigt line-shape profiles were performed among various published results for both N 2 O and CO. Selected data allowed for developing semi-empirical models, which were used to extrapolate/interpolate existing data to update broadening parameters of all the lines of these molecules in the HITRAN database. In addition to the line broadening parameters (and their temperature dependences), the pressure shift values were revised for N 2 O and CO broadened by air and self for all the bands. The air and self speed-dependence of the broadening parameter for these two molecules were added for every transition as well. Furthermore, we determined the first-order line-mixing parameters using the Exponential Power Gap (EPG) scaling law. These new parameters are now available at HITRAN o n l i n e. [ABSTRACT FROM AUTHOR]

• The theorem of Hose and Taylor is applied to molecular spectroscopy to deduce asymmetric top quantum labels. • Asymmetric top quantum labels are deduced to a high degree of fidelity using variational methods. • Projection of total angular momentum onto molecule fixed axis can be a good quantum number. Molecular line lists, particularly those computed for high temperature applications, often have very few states assigned local quantum numbers, i.e rotational and vibrational quantum labels. These are often important components for accurately determining line shape parameters required for radiative transfer simulations. Through variational calculations, the projection of the total angular momentum onto the molecule fixed axis (k) is investigated in the Radau internal coordinate system to determine when it can be considered a good quantum number. In the Radau coordinate system, when the square of the th component of the wavefunction is greater than one half, then we can classify k as a good quantum number in accordance with the theorem of Hose and Taylor, a quantum analogue of the Kolmogorov–Arnold–Moser theorem. When the theorem is satisfied, it is shown that k can reliably be used to determine oblate and prolate quantum labels K a and K c. This approach is tested on the states of the water and ozone molecules. [ABSTRACT FROM AUTHOR]

Highlights: [•] HITRAN2012 database is released. [•] New laboratory and theoretical spectroscopic results reported. [•] Spectral line lists for molecular species added or updated. [•] ASA/HITRAN conference was held in Reims, France, August 2012. [ABSTRACT FROM AUTHOR]

• Best determined line-shape parameters are collected for self- and air-broadened CO 2 lines, and by creating sets of semi-empirical models, all the CO 2 transitions in the HITRAN are updated using the Voigt and non-Voigt parametrizations. • A semi-empirical approach was examined for calculating the line shifts of air- and CO 2 broadened CO 2 lines, yielding reliable pressure shift values. • The CO 2 line mixing package is updated and the first-order line-mixing parameters will be added for every transition in the HITRAN to be used for the bands with the P and R branches. • Significant improvement in the residuals was achieved when validating the updated parameters with laboratory spectra. Characterizing and modeling atmospheric CO 2 with a sub-percent accuracy necessitates high-quality spectroscopic line-shape parameters. For this goal, we collected the best experimentally and theoretically determined parameters for self- and air-broadened CO 2 lines to create sets of semi-empirical models for updating all of the carbon dioxide transitions in the HITRAN database using the Voigt and non-Voigt parametrizations. Based on the available data, we estimated the air- and CO 2 -broadening half widths, their associated temperature exponents, and the speed dependence of the broadening together with its temperature dependence for every transition in HITRAN. Furthermore, a semi-empirical approach educated by the most reliable experimental data was used to calculate the line shifts of air- and self-broadened CO 2 absorption lines. The updated line-shape parameters were used for calculating the first-order line-mixing parameters for every transition using the program developed by Lamouroux et al. [JQSRT 151 , 88 (2015)]. The same program was used to calculate absorption coefficients with full line-mixing by using the updated parameters. In order to verify these new data, two different sets of laboratory spectra were used to compare with the absorption coefficient calculated by the line-mixing package program and the HITRAN Application Programming Interface (HAPI) for which necessary functionality was implemented. The updated data is proposed for the next edition of HITRAN (2020). Thanks to the relational structure of the HITRAN database, we are able to provide separate consistent and complete sets of parameters in Voigt and speed-dependent Voigt parametrizations for every line of carbon dioxide. [ABSTRACT FROM AUTHOR]

• New dipole moment surface provides excellent calculated intensities. • Calculated line lists agrees very well with many experimental and theoretical sources. • Transition intensities are sensitive to subtle changes in the potential. • Further work is required in the visible. New line lists are presented for the two most abundant water isotopologues; H 2 16O and H 2 18O. The H 2 16O line list extends to 25710 cm − 1 with intensity stabilities provided via ratios of calculated intensities obtained from two different semi-empirical potential energy surfaces. The line list for H 2 18O extends to 20000 cm − 1. The minimum intensity considered for all is 10 − 30 cm molecule − 1 at 296 K, assuming 100% abundance for each isotopologue. Fluctuation of calculated intensities caused by changes in the underlying potential energy are found to be significant, particularly for weak transitions. Direct comparisons are made against eighteen different sources of line intensities, both experimental and theoretical, many of which are used within the HITRAN2016 database. With some exceptions, there is excellent agreement between our line lists and the experimental intensities in HITRAN2016. In the infrared region, many H 2 16O bands which exhibit intensity differences of 5–10% between to the most recent 'POKAZATEL' line list (Polyansky et al., [Mon. Not. Roy. Astron. Soc. 480 , 2597 (2018)] and observation, are now generally predicted to within 1%. For H 2 18O, there are systematic differences in the strongest intensities calculated in this work versus those obtained from semi-empirical calculations. In the visible, computed cross sections show smaller residuals between our work and both HITRAN2016 and HITEMP2010 than POKAZATEL. While our line list accurately reproduces HITEMP2010 cross sections in the observed region, residuals produced from this comparison do however highlight the need to update line positions in the visible spectrum of HITEMP2010. These line lists will be used to update many transition intensities and line positions in the HITRAN2016 database. [ABSTRACT FROM AUTHOR]

Highlights • Reconciliation of ozone microwave data in the HIRAN and JPL databases. • Explanation of theory for centrifugal distortion of permanent dipole. • Far-infrared absolute intensity measurement. • Impact of intensity adjustment for ozone remote sensing. Abstract This note provides a citable reference to a database reconciliation effort for ozone pure rotational intensities. The permanent dipole moment and theoretical adjustments for centrifugal distortion are utilized in a predictive calculation that is compared to experimental measurements. This prediction has been available in the JPL spectral line catalog since 2005, but has been at odds with the HITRAN database, which was originally based on an atlas provided by Flaud (HITRAN 1992) and subsequently scaled by 4% (HITRAN 2004). Using a modified partition function and isotopic abundance factor, the JPL 2005 prediction has now been utilized to create a self-consistent entry as an interim update to the HITRAN2016 database. Ramifications of the intensity change for users of HITRAN versions 2004–2012 are discussed. New pure rotational intensity measurements were carried out supporting the validity of the JPL 2005 database. [ABSTRACT FROM AUTHOR]

Abstract: The very weak system of the three 17O isotopologues of oxygen – 16O17O, 17O18O and 17O2 – was studied by high sensitivity CW-Cavity Ring Down Spectroscopy. The spectra of a 17O highly enriched sample were recorded at room temperature between 7640 and 7917cm−1 and at liquid nitrogen temperature in the 7876–7893cm−1 region. The magnetic dipole (0–0) band was observed for all three 17O isotopologues. At liquid nitrogen temperature, some of the transitions were observed with partially resolved hyperfine splitting due to the 17O nuclear spin. The electric quadrupole (0–0) band and the (1–1) hot band were also observed for the 16O17O and 17O2 species. The rotational and hyperfine spectroscopic parameters of the and a 1Δ g states of the three studied isotopologues were derived from a global fit of the measured line positions and microwave and Raman measurements available in the literature. The spectroscopic constants of the a 1Δ g (v=0, 1) states of 17O2 are reported for the first time. [Copyright &y& Elsevier]

Abstract: The high sensitivity absorption spectrum of the band of 16O17O, 17O18O and 17O2 has been recorded by CW-Cavity Ring Down Spectroscopy near 1.27μm. The spectra were obtained between 7640 and 7917cm−1 with a 17O-enriched sample at room temperature and at 80K. Due to the I =5/2 nuclear spin of the 17O atom, the nuclear hyperfine structure of the transitions could be partly resolved at low temperature. The parameter coupling of the nuclear spin to the electronic angular momentum in the a 1Δg state has been derived for the three studied isotopologues of oxygen. [ABSTRACT FROM AUTHOR]

Abstract: The CW-Cavity Ring Down Spectroscopy (CW-CRDS) technique has been used to record the high sensitivity absorption spectrum of the a 1Δg–X 3 Σ g − band of oxygen near 1.27μm. The spectra were obtained between 7640 and 7917cm−1 with “natural” oxygen and with a sample highly enriched in 18O. The absolute intensities of 376 and 643 oxygen transitions were measured in the two spectra. They include the a 1Δg−X 3 Σ g − (0–0) bands of 16O2, 16O18O, 16O17O, 17O18O and 18O2. The (0–0) bands of 16O2 and 18O2 show weak quadrupole transitions with line intensities ranging from 1×10−30 to 1.9×10−28 cm/molecule. They are accompanied by the a 1Δg−X 3 Σ g − (1–1) hot bands, which are reported for the first time. The line profiles of the transitions of the 16O17O and 17O18O isotopologues were observed to be broadened due to an unresolved magnetic hyperfine structure. Accurate spectroscopic parameters of the different energy levels involved in the observed bands were derived from a global fit of the observed line positions, combined with microwave and Raman measurements available in the literature. [ABSTRACT FROM AUTHOR]

Abstract: The room-temperature nitrogen- and oxygen-broadening coefficients of hydrogen cyanide spectral lines have been measured in the 0.5–3THz (17–100cm−1) frequency range (purely rotational transitions with 5⩽J⩽36) by a continuous-wave terahertz spectrometer based on a photomixing source. An improved version of the Robert and Bonamy semiclassical formalism has been used to calculate the oxygen-broadening coefficients and resulted in a good agreement with these measurements. The nitrogen and oxygen data are combined to provide the air-broadening coefficients as used by the HITRAN database. A significant difference is observed between the measured and tabulated values for transitions with high values of the rotational quantum number. A new polynomial representation is suggested for inclusion in HITRAN. A similar polynomial expression has been derived for the nitrogen broadening to aid the studies of Titan''s atmosphere. [Copyright &y& Elsevier]

• Experimentally accurate HCN line list between vibrational states up to 10,300 cm − 1. • Line list includes all vibrational states up to 7000 cm − 1. • HITRAN sensitivity limit for all rotational manifolds. • High quality visual validation method of the line list with measured spectra. A hydrogen cyanide line list (MOMeNT-90) developed for the HITRAN spectroscopic database covering 0–7500 cm − 1 range (λ > 1330 nm) is presented. The line list is a combination of the variationally calculated line intensities with line centers obtained from experimentally derived energy levels. There are four features of this line list which distinguishes it from the previously calculated ones. First, the intensities are variationally calculated using a new, high-accuracy potential energy surface (PES) obtained via fitting the PES using experimental energy levels. Second, a new ab initio dipole moment surface was calculated at a high level of quantum chemical theory. Based on the wave functions calculated with the new PES and use of the new dipole moment surface, line intensities are reported which of similar accuracy to those obtained experimentally. Third, the calculated states are mapped to the existing complete set of experimental eigenenergies, resulting in an assigned and complete HCN line list down to the HITRAN intensity threshold of 10 − 34 cm/molecule. Fourth, extensive validation of the line list is provided through line-by-line comparisons of the results with measured HCN spectra which confirms the accuracy of the intensities used to construct the line list. The line list is augmented with parameters needed to calculate line widths for pressure-dependent simulations. [ABSTRACT FROM AUTHOR]

• High-resolution spectra of formaldehyde in the 1250 - 1390 cm−1 range from optical frequency comb Fourier transform spectroscopy. • Empirical line positions and intensities of 747 rovibrational transitions from the ν 3 , ν 4 and ν 6 fundamental bands and four hot bands. • Extended and improved global analysis of formaldehyde spectrum using the MARVEL (measured active vibration-rotation energy levels) procedure. We use optical frequency comb Fourier transform spectroscopy to record high-resolution, low-pressure, room-temperature spectra of formaldehyde (H 2 12C16O) in the range of 1250 to 1390 cm−1. Through line-by-line fitting, we retrieve line positions and intensities of 747 rovibrational transitions: 558 from the ν 6 band, 129 from the ν 4 band, and 14 from the ν 3 band, as well as 46 from four different hot bands. We incorporate the accurate and precise line positions (0.4 MHz median uncertainty) into the MARVEL (measured active vibration-rotation energy levels) analysis of the H 2 CO spectrum. This increases the number of MARVEL-predicted energy levels by 82 and of rovibrational transitions by 5382, and substantially reduces uncertainties of MARVEL-derived H 2 CO energy levels over a large range: from pure rotational levels below 200 cm−1 up to multiply excited vibrational levels at 6000 cm−1. This work is an important step toward filling the gaps in formaldehyde data in the HITRAN database. [ABSTRACT FROM AUTHOR]

Positions and intensities for transitions in the 1←0 bands of the four CO isotopologues ( 12 C 16 O, 13 C 16 O, 12 C 18 O and 13 C 18 O) were retrieved from analyses of spectra of different low-pressure pure samples and high-pressure air-broadened mixtures (1940–2260 cm −1 ) in two different multispectrum fittings involving selected groups of 21 (for 13 C 16 O) and 20 (for 12 C 18 O) spectra. Air-broadened half-width and air-shift coefficients, their temperature dependences, line mixing via off-diagonal relaxation matrix element coefficients for CO-air collision systems, and quadratic speed dependence parameters were measured for 13 C 16 O and 12 C 18 O transitions. In both the fittings, two low-pressure room-temperature spectra of a high purity natural sample of CO recorded with the Kitt Peak FTS were included to retrieve the positions and intensities of 12 C 16 O transitions. All other spectra in the fittings were obtained with either 13 C-enriched or 18 O-enriched samples using the JPL Bruker IFS-125HR FTS. Four absorption cells with path lengths between 0.5131(5) and 20.38(2) cm were used to record the data. The cells are temperature controlled, except for the shortest cell. Positions and intensities for the 1←0 band transitions were determined from the retrieved ro-vibrational constants ( G, B, D and H ), band intensity and Herman-Wallis parameters by applying the theoretical quantum mechanical expressions. The band strengths of 12 C 16 O, 12 C 18 O and 13 C 18 O are very close (∼0.3%) to HITRAN2012 values but for 13 C 16 O the band strength is ∼4.8% larger than the HITRAN2012 and 2.6% larger than the HITRAN2016 value. [ABSTRACT FROM AUTHOR]

Recently, several empirical models of the potential energy function (PEF) of the ground electronic state of CO have been developed by Coxon and Hajigeorgiou using the direct-potential-fit (DPF) analysis. These models reproduce more than twenty thousand of observed ro-vibrational line positions within their experimental accuracies and follow the theoretically predicted long-range asymptotic behavior of the potential beyond Le Roy's radius. However, the applicability of these models to calculations of the intensities of weak transitions is not obvious due to limitations discussed in this work. Here, we make the next step by imposing an additional requirement that the model has to display physical behavior outside the region to which the available spectroscopic data pertain. We perform ab initio calculations of the potential in the short-range region r  = 0.3–0.8 Å where the potential increases well above the dissociation limit and include these data along with the estimated uncertainties in the DPF analysis. At smaller r , our PEF tends to the well-known united-atom limit. In the long-range region, it follows the ab initio data with their estimated accuracies available in the literature. On top of the above, the model is analytical, i.e. it has continuous derivatives of all orders. The model constructed is a linear function of twenty three adjustable parameters, and a non-linear function of additional five parameters. The properties of the new PEF are investigated in comparison with the previous empirical model due to Coxon and Hajigeorgiou (2004). Our PEF provides reproduction of all observed lines at the same level of accuracy. The new potential changes the intensities of high overtone transitions dramatically. In addition, we find that the anomalies in the purely rotational and ro-vibrational spectra change their intensities between the two PEFs even for the low-v bands. [ABSTRACT FROM AUTHOR]

Total internal partition sums (TIPS) are reported for 166 isotopologues of 51 molecules important in planetary atmospheres. Molecules 1 to 50 are taken from the HITRAN2016 list, and, in some cases, additional isotopologues are considered for some of the molecules. Molecules 51–53 are C 3 H 4 , CH 3 , and CS 2 , respectively. TIPS are not reported for the O atom and CF 4 ; thus, while there are 53 species in the list, data are reported for 51 molecules. The TIPS are determined by various methods from 1 K to a T max that ensures the TIPS reported have converged. These data are provided with HITRAN2016 and a new version of the TIPS code is available in both FORTRAN and python languages. [ABSTRACT FROM AUTHOR]

The accuracy of atmospheric trace gas retrievals depends directly on the accuracy of the molecular absorption model used within the retrieval algorithm. For remote sensing of well-mixed gases, such as carbon dioxide (CO 2 ), where the atmospheric variability is small compared to the background, the quality of the molecular absorption model is key. Recent updates to the 1.6 µm and 2.06 µm CO 2 absorption model used within the Orbiting Carbon Observatory (OCO-2) algorithm are described and validated. A set of 164 atmospheric spectra from the Total Carbon Column Observing Network (TCCON) is used to compare three models, both previous and current versions of absorption coefficient tables (largely derived from recent multispectrum fitting analyses targeted specifically at these bands) as well as a recent model constructed to use the HITRAN 2012 compilation. Both spectral residuals and retrieved column-averaged CO 2 mixing ratios (XCO 2 ) are included in the comparison. Absorption coefficients based on the updated multispectrum fitting analyses provide residuals comparable to or smaller than either the previous version of the multispectrum fits or the HITRAN 2012-based model. For the 2.06 µm band the updated model finds noticeably lower residuals for low water content cases. It is found that apart from a scaling factor the prior and updated absorption models result in similar retrieved values of XCO 2 for the 2.06 µm band and a slightly different airmass dependence for the 1.6 µm band. [ABSTRACT FROM AUTHOR]

A new line list including positions and absolute transition strengths (in the form of Einstein A values and oscillator strengths) has been produced for the OH ground X 2 Π state rovibrational (Meinel system) and pure rotational transitions. All possible transitions are included with v ′ and v ″ up to 13, and J up to between 9.5 and 59.5, depending on the band. An updated fit to determine molecular constants has been performed, which includes some new rotational data and a simultaneous fitting of all molecular constants. The absolute transition strengths are based on a new dipole moment function, which is a combination of two high level ab initio calculations. The calculations show good agreement with an experimental v = 1 lifetime, experimental μ v values, and Δv=2 line intensity ratios from an observed spectrum. To achieve this good agreement, an alteration in the method of converting matrix elements from Hund׳s case (b) to (a) was made. Partitions sums have been calculated using the new energy levels, for the temperature range 5–6000 K, which extends the previously available (in HITRAN) 70–3000 K range. The resulting absolute transition strengths have been used to calculate O abundances in the Sun, Arcturus, and two red giants in the Galactic open and globular clusters M67 and M71. Literature data based mainly on [O I] lines are available for the Sun and Arcturus, and excellent agreement is found. [ABSTRACT FROM AUTHOR]

Abstract: This paper is the fourth of a series of papers 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 paper presents energy level and transition data for the following doubly and triply substituted isotopologues of water: D2 16O, D2 17O, and D2 18O. 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 0–14016, 0–7969, and 0–9108cm−1 for D2 16O, D2 17O, and D2 18O, respectively. For D2 16O, D2 17O, and D2 18O, 53534, 600, and 12167 lines are considered, respectively, from spectra recorded in absorption at room temperature and in emission at elevated temperatures. The number of validated energy levels is 12269, 338, and 3351 for D2 16O, D2 17O, and D2 18O, respectively. The energy levels have been checked against the ones determined, with an average accuracy of about 0.03cm−1, from variational rovibrational computations employing exact kinetic energy operators and an accurate potential energy surface. Furthermore, the rovibrational labels of the energy levels have been validated by an analysis of the computed wavefunctions using the rigid-rotor decomposition (RRD) scheme. The extensive list of MARVEL lines and levels obtained is deposited in the Supplementary Material of this paper, in a distributed information system applied to water, W@DIS, and on the official MARVEL website, where they can easily be retrieved. [Copyright &y& Elsevier]

• The ab initio dipole moment was evaluated in a wide range of inter-atomic separation r. • The semi-empirical dipole moment was reconstructed remove equation using both the experimental intensities and the ab initio dipole moments. • The line lists were calculated for all CO isotopologues. [Display omitted] The semi-empirical permanent electric dipole-moment function (DMF) for the ground state of the CO molecule has been reconstructed analytically in the entire range of the inter-nuclear distance r ∈ [ 0 , + ∞) by means of the simultaneous non-linear least-squares fitting (NLLSF) of the selected experimental intensities for the main 12 C 16 O isotopologue (including those with sub-percent uncertainties) and the ab initio permanent dipole moment. The ab initio DMFs were evaluated using single-reference coupled cluster (SR-CCSD(T)) and multi-reference averaged coupled-pair functional (MR-ACPF) methods. The ab initio data were involved in the NLLSF procedure to propagating smoothly the semi-empirical DMF outside the local region covered by the experimental intensities for the lowest vibrational v ′ ≤ 11 levels. The derived mass-invariant DMF possesses the physically correct asymptotic behavior in both the united-atom and dissociation limits as well as reproduces the vast majority of the measured intensities in v ″ = 0 → v ′ ∈ [ 0 , 6 ] and v ″ = 1 → v ′ = 4 , 5 bands within their experimental uncertainties. The resulting DMF and the mass-corrected potential-energy function of Meshkov et al. (2018)[16] were used to upgrade line lists for all CO isotopologues in the wide range of vibrational and rotational quantum numbers v ∈ [ 0 , 41 ] , Δ v ∈ [ 0 , 6 ] , J ∈ [ 0 , 150 ] (J ∈ [ 0 , 200 ] for the 0-0 and 1-0 bands). The predicted intensities are compared with their experimental counterparts, which were not involved in the present NLLSF, to highlight presumable random and systematic errors in the measured data; in particular, the intensities in the "abnormal" 0 → 5 band of the 12 C 16 O isotopologue and some other bands of minor isotopologues should be revisited experimentally. The resultant line list should be considered superior to previous efforts in terms of accuracy. [ABSTRACT FROM AUTHOR]

Abstract: This is the third of a series of articles reporting critically evaluated rotational–vibrational line positions, transition intensities, and energy levels, with associated critically reviewed labels and uncertainties, for all the main isotopologues of water. This paper presents experimental line positions, experimental-quality energy levels, and validated labels for rotational–vibrational transitions of the most abundant isotopologue of water, H2 16O. The latest version of the MARVEL (Measured Active Rotational–Vibrational Energy Levels) line-inversion procedure is used to determine the rovibrational energy levels of the electronic ground state of H2 16O from experimentally measured lines, together with their self-consistent uncertainties, for the spectral region up to the first dissociation limit. The spectroscopic network of H2 16O containstwo components, an ortho (o) and a para (p) one. For o-H2 16O and p-H2 16O, experimentally measured, assigned, and labeled transitions were analyzed from more than 100 sources. The measured lines come from one-photon spectra recorded at room temperature in absorption, from hot samples with temperatures up to 3000K recorded in emission, and from multiresonance excitation spectra which sample levels up to dissociation. The total number of transitions considered is 184667 of which 182156 are validated: 68027 between para states and 114129 ortho ones. These transitions give rise to 18486 validated energy levels, of which 10446 and 8040 belong to o-H2 16O and p-H2 16O, respectively. The energy levels, including their labeling with approximate normal-mode and rigid-rotor quantum numbers, have been checked against ones determined from accurate variational nuclear motion computations employing exact kinetic energy operators as well as against previous compilations of energy levels. The extensive list of MARVEL lines and levels obtained are deposited in the supplementary data of this paper, as well as in a distributed information system applied to water, W@DIS, where they can easily be retrieved. [Copyright &y& Elsevier]

Abstract: 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 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 0–22708, 0–1674, and 0–12105cm−1 for HD16O, HD17O, and HD18O, respectively. For HD16O, 54740 transitions were analyzed from 76 sources, the lines come from spectra recorded both at room temperature and from hot samples. These lines correspond to 36690 distinct assignments and 8818 energy levels. For HD17O, only 485 transitions could be analyzed from three sources; the lines correspond to 162 MARVEL energy levels. For HD18O, 8729 transitions were analyzed from 11 sources and these lines correspond to 1864 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 296K 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 [Tennyson, et al. J Quant Spectr Rad Transfer 2009;110:573–96], has been updated. [Copyright &y& Elsevier]

Abstract: This is the first part of a series of articles reporting critically evaluated rotational–vibrational line positions, transition intensities, pressure dependence and energy levels, with associated critically reviewed assignments and uncertainties, for all the main isotopologues of water. The present article contains energy levels and data for line positions of the singly substituted isotopologues H2 17Oand H2 18O. The procedure and code MARVEL, standing for measured active rotational–vibrational energy levels, is used extensively in all stages of determining the validated levels and lines and their self-consistent uncertainties. The spectral regions covered for both isotopologues H2 17O and H2 18O are . The energy levels are checked against ones determined from accurate variational calculations. The number of critically evaluated and recommended levels and lines are, respectively, 2687 and 8614 for H2 17O, and 4839 and 29364 for H2 18O. The extensive lists of MARVEL lines and levels obtained are deposited in the Supplementary Material, as well as in a distributed information system applied to water, W@DIS, where they can easily be retrieved. A distinguishing feature of the present evaluation of water spectroscopic data is the systematic use of all available experimental data and validation by first-principles theoretical calculations. [Copyright &y& Elsevier]

• Far-infrared spectrum of cyanoacetylene recorded for the first time. • 24 newly observed ro-vibrational bands. • About 17000 experimental transitions analyzed for 22 states. • Anharmonic resonances fully accounted for the 2nd polyad system around 1100 cm-1. • Rotational and ro-vibrational line list up to 3360 cm-1. • Rotational and ro-vibrational global analysis. The far-infrared spectrum of HC 3 N has been recorded at high resolution between 70 and 500 cm − 1 using synchrotron radiation. Four prominent features, i.e., ν 7 , ν 6 − ν 7 , ν 4 − ν 6 , and 2 ν 7 have been identified in the spectrum together with many associated hot bands. In addition, rotational transitions for the interacting v 4 = v 7 = 1 , (v 6 = 2 , v 7 = 1) , (v 5 = 1 , v 7 = 2) , and v 7 = 5 vibrationally excited states have been recorded in the millimeter/submillimeter region. The newly assigned transitions, together with those reported previously, form a comprehensive data set including about 17 000 transitions, which involves almost all the vibrational states of HC 3 N lying below 1300 cm − 1 plus some excited states with energies between 2075 and 3550 cm − 1. These data have been fitted to an effective Hamiltonian which takes into account rotational and vibrational l -type resonance effects, together with a number of anharmonic interaction terms. On average, all the analysed data are reproduced within the experimental accuracy. About 90 000 rotational and ro-vibrational transition frequencies have been computed on the basis of the spectroscopic constants obtained from the global fit in order to support data interpretation and astronomical searches in the interstellar medium and planetary atmospheres. Part of these data is included in the 2020 release of the HITRAN database. [ABSTRACT FROM AUTHOR]

• Total internal partition sums (TIPS) are reported for 178 isotopologues of 57 molecules important in planetary atmospheres. • TIPS are reported from 1 K to a T max that insures the TIPS have converged. • The new versions of the TIPS code are available in both FORTRAN and python languages. Total internal partition sums (TIPS) are reported for the 181 isotopologues of 57 molecules important in planetary atmospheres. Molecules 1 to 55, with the exception of #34 atomic oxygen, are taken from the HITRAN2020 list, and for some molecules additional isotopologues are considered. Molecules 56 and 57 are C 3 H 4 , CH 3 , respectively. New to TIPS are the calculations for 12CH 4 , 13CH 4 , 12CH 3 D, 13CH 3 D, 14N16O, 15N16O, 14N18O, 16O32S18O, 33S16O 2 , 15N16O 2 , 18OH, 16OD, 35Cl16O, 37Cl16O, 16O13C34S, 32S19F 6 , 12C 2 H 5 D, 12C 2 H 3 D, 12C19F 4 , 12CH 3 19F, 70GeH 4 , 72GeH 4 , 73GeH 4 , 74GeH 4 , 76GeH 4 , 12CH 3 127I, 13CH 3 127I, and 14N19F 3. In addition, all the molecules/isotopologues that were not recalculated for TIPS2017 (Gamache et al. , JQSRT 203, 70, 2017) have been recalculated using the 2014 CODATA physical constants. The TIPS are determined by various methods, generally from 1 to 5000 K. These data are provided with HITRAN2020 and a new version of the TIPS code is available in both FORTRAN and python languages. [Display omitted] [ABSTRACT FROM AUTHOR]

Theoretical calculations are contributing a significantly higher proportion of data to contemporary spectroscopic databases, which have traditionally relied on experimental observations and semi-empirical models. It is now a common procedure to extend calculated line lists to include ro-vibrational transitions between all bound states of the ground electronic state up to the dissociation limit. Advanced ab initio methods are utilized to calculate the potential energy and dipole moment surfaces (PESs and DMSs), and semi-empirical PESs are then obtained by combining ab initio and experimental data. The objective is to reach high accuracy in the calculated transition intensities for all parts of spectrum, i.e. to increase the predictive power of the model. We show that in order to perform this task, one needs, in addition to the standard improvements of the PES and DMS in the spectroscopically accessible regions, to extend the ab initio calculations of the PES towards the united-atom limit along the stretching coordinates. The argument is based on the correlation between the intensities of high-overtone transitions and the repulsive potential wall that has previously been theoretically established for diatomic molecules and is empirically extended here to linear and nonlinear triatomic molecules. We generate partial line lists for water and ozone, and together with an already available line list for carbon dioxide, we derive the normal intensity distribution, which is a direct consequence of this correlation. The normal distribution is not an instrument to compute highly accurate intensities, rather it is a means to analyse the intensities computed by the traditional methods. • Overtone vibrational transitions in water, ozone, and carbon dioxide obey the Normal Intensity Distribution (NID) earlier established for diatomic molecules. • The NID has proved to be a useful tool for validating the intensities of overtone transitions. • Manifestation of the NID implies that the intensities of overtone transitions depend on the repulsive branch of the potential energy far from equilibrium. • In order to reach high accuracy in the calculations, the effect of the repulsive wall must be taken into account even for spectroscopically important transitions. • Ab initio calculations of the potential and dipole moment must extend to regions far from equilibrium. Image, graphical abstract [ABSTRACT FROM AUTHOR]