Spectroscopy is an established and indispensable tool in science, industry, agriculture, medicine, surveillance, etc.. The potential user of spectral data, which is not available in HITRAN¹ or other databases, searches the spectroscopy publications. After finding the desired publication, the user very often encounters the following problems: 1) They cannot find the data described in the paper. There can be many reasons for this: nothing is provided in the paper itself or supplementary material; the authors are not responding to any requests; the web links provided in the paper have long been broken; etc. 2) The data is presented in a reduced form, for instance through the fitted spectroscopic constants. While this is a long-standing practice among spectroscopists, there are numerous serious problems with this practice, such as users getting different energy and intensity values because of different representations of the solution to the Hamiltonian, or even just despairing of trying to generate usable line lists from the published constants.
  Properly providing the data benefits not only users but also the authors of the spectroscopic research. We will show that this increases citations to the spectroscopy papers and visibility of the research groups. We will also address the quite common issue when researchers obtain the data, but do not feel that they have time, interest or resources to write an article describing it. There are modern tools that would allow one to make these data available to potential users and still get credit for it. However, this is a worst case scenario recommendation, i.e., publishing the data in a peer-reviewed journal is still the preferred way.
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¹L. S. Rothman, I. E. Gordon, et al. "The HITRAN 2012 molecular spectroscopic database," JQSRT 113, 4-50 (2013).

  In order to improve and extend existing HITRAN¹ and HITEMP² data for carbon monoxide, the ro-vibrational line lists were computed for all transitions of nine isotopologues of the CO molecule, namely ¹²C¹⁶O, ¹²C¹⁷O, ¹²C¹⁸O, ¹³C¹⁶O, ¹³C¹⁷O, ¹³C¹⁸O, ¹⁴C¹⁶O, ¹⁴C¹⁷O, and ¹⁴C¹⁸O in the electronic ground state up to v = 41 and J = 150. Line positions and intensity calculations were carried out using a newly-determined piece-wise dipole moment function (DMF) in conjunction with the wavefunctions calculated from a previous experimentally-determined potential energy function of Coxon and Hajigeorgiou³. Ab initio calculations and a direct-fit method which simultaneously fits all the reliable experimental ro-vibrational matrix elements has been used to construct the piecewise dipole moment function.
  To provide additional input parameters into the fit, new Cavity Ring Down Spectroscopy experiments were carried out to enable measurements of the lines in the 4-0 band with low uncertainty (Grenoble) as well as the first measurements of lines in the 6-0 band (Hefei).
  Accurate partition sums have been derived through direct summation for a temperature range from 1 to 9000 Kelvin. A complete set of broadening and shift parameters is also provided and now include parameters induced by CO₂ and H₂ to aid planetary applications.
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¹L. S. Rothman, I. E. Gordon, et al. "The HITRAN 2012 molecular spectroscopic database," JQSRT 113, 4-50 (2013). ²L. S. Rothman, I. E. Gordon, et al. "HITEMP, the high-temperature molecular spectroscopic database," JQSRT 111, 2139-2150 (2010). ³J. Coxon and P. Hajigeorgiou. "Direct potential fit analysis of the X¹Σ⁺ ground state of CO," J. Chem. Phys. 121, 2992-3008 (2004).

Two spectroscopic relational databases, denoted MeCaSDa and ECaSDa, have been implemented for methane and ethene, and included in VAMDC (Virtual Atomic and Molecular Data Centre, http://portal.vamdc.eu/vamdc_portal/home.seam) [1]. These databases collect calculated spectroscopic data from the accurate analyses previously performed for the electronic ground state of methane, ethene, and some of their isotopologues: ¹²CH₄, ¹³CH₄, and ¹²C₂H₄ [2]. Both infrared absorption and Raman scattering lines are included. The polyad structures are reported and the transitions are precisely described by their energy, their intensity and the full description of the lower and upper states involved in the transitions. Very recently, we also built on the same model two new databases, named SHeCaSDa and TFMeCaSDa for the SF₆ and CF₄ greenhouse gas molecules, respectively. The relational schemas of these four databases are equivalent and optimized to enable the better compromise between data retrieval and compatibility with the XSAMS (XML Schema for Atoms, Molecules, and Solids) format adopted within the VAMDC European project.  

Figure We present comprehensive line lists of CH₄ at high temperatures for the pentad and octad region (2400-5000 cm⁻¹). These spectra improve on our previous emission measurements for this region¹ by using a new quartz sample cell in conjunction with a tube furnace (pictured). Ten temperatures have been recorded from room temperature up to 1000^°C and our technique involves the acquisition of four separate Fourier transform infrared spectra at each temperature, thus accounting for both the emission and absorption of the molecule and the cell. By combining these four spectra we obtain true transmission spectra of hot CH₄ in this region. Analysis of this set of spectra enables the production of a line list that includes the position, intensity and empirical lower state energy. Our spectra and line lists can be used directly to model planetary atmospheres and brown dwarfs.
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¹Hargreaves, R.J., Beale, C.A., Michaux, L., Irfan, M., & Bernath, P.F. 2012, ApJ, 757, 46

We present the results of prediction of energy levels of various water isotopologues using the fit of mass independent part of potential energy surface (PES) of H₂¹⁶O only. Fit was done in such a way that mass dependent part of PES - adiabatic correction of H₂¹⁶O was used during the fit and also non-adiabatic mass-dependent correction to kinetic energy. When the predicted levels of other isotopologues have been calculated, the same mass independent surface as for H₂¹⁶O was used and both adiabatic and non-adiabatic corrections of the corresponding isotopologues have been employed. As a result the discrepancy between predicted and observed energy levels of H₂¹⁷O and H₂¹⁸O were almost of the same value as for H₂¹⁶O for the levels of H₂¹⁷O and H₂¹⁸O known experimentally. It is natural to suppose, that at least for the levels of H₂¹⁶O included in the fit, the same accuracy of prediction of H₂¹⁷O and H₂¹⁸O levels should be expected. Thus, the procedure transferring experimental knowledge of the major isotopologues to the minor isotopologues without the fitting of the levels of these minor isotopologues , has been developed. For other isotopologues such as D₂¹⁶O and HDO the discrepancy are less perfect, but still within about 0.1 cm⁻¹. These results provide us with a very accurate tool for the prediction of energy levels of minor isotopologues.

As the simplest polyatomic molecule, H₃⁺ serves as an ideal benchmark for theoretical predictions of rovibrational energy levels. By strictly ab initio methods, the current accuracy of theoretical predictions is limited to an impressive one hundredth of a wavenumber,¹ which has been accomplished by consideration of relativistic, adiabatic, and non-adiabatic corrections to the Born-Oppenheimer PES. More accurate predictions rely on a treatment of quantum electrodynamic effects, which have improved the accuracies of vibrational transitions in molecular hydrogen to a few MHz.² High precision spectroscopy is of the utmost importance for extending the frontiers of ab initio calculations, as improved precision and accuracy enable more rigorous testing of calculations. Additionally, measuring rovibrational transitions of H₃⁺ can be used to predict its forbidden rotational spectrum. Though the existing data can be used to determine rotational transition frequencies, the uncertainties are prohibitively large.³ Acquisition of rovibrational spectra with smaller experimental uncertainty would enable a spectroscopic search for the rotational transitions. The technique Noise Immune Cavity Enhanced Optical Heterodyne Velocity Modulation Spectroscopy, or NICE-OHVMS has been previously used to precisely and accurately measure transitions of H₃⁺, CH₅⁺, and HCO⁺ to sub-MHz uncertainty.⁴ A second module for our optical parametric oscillator has extended our instrument's frequency coverage from 3.2-3.9 μm to 2.5-3.9 μm. With extended coverage, we have improved our previous linelist by measuring additional transitions.
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¹O. L. Polyansky, et al. Phil. Trans. R. Soc. A (2012), 370, 5014-5027. ²J. Komasa, et al. J. Chem. Theor. Comp. (2011), 7, 3105-3115. ³C. M. Lindsay, B. J. McCall, J. Mol. Spectrosc. (2001), 210, 66-83. ⁴J. N. Hodges, et al. J. Chem. Phys. (2013), 139, 164201.

A precise, repeatable and stable optical frequency source is required for many modern spectroscopy experiments. Frequency combs have proven invaluable to many, but are not obtainable for others due to their high cost. Using a GPS disciplined oscillator, a stabilized Fabry-Pérot cavity, a relatively low-cost wavemeter and standard RF equipment, we have achieved a reliable laser system with a 10⁻⁹ or better frequency uncertainty at a fraction of the cost. With this system we have measured approximately 3000 transitions in ¹³⁰Te₂ continuously between 664 and 676 THz to  ∼  0.0001 cm⁻¹ precision. The system is described in detail, and the possibility of improving our knowledge of the excited states of ¹³⁰Te₂ is considered.

The electronic spectrum of ¹³⁰Te₂ serves as a frequency standard for many spectroscopic investigations. We scanned the molecule in the region 664 to 676 THz using a tunable diode laser to create an atlas of transition lines, in line with the previous investigations of Cariou, et al.¹ The BO⁺_u ← XO⁺_g transition was studied in great detail using the precise data for the X band from Verges, et al.² Using this data, the number of vibrational bandheads was identified. This allowed the rotational parameters B, D and H to be precisely obtained for each bandhead. These results are combined to obtain the appropriate spectroscopic parameters for the B₀ electronic band. The results of this investigation will be presented.
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¹Cariou, J. and Luc, P. Ätlas Du Spectre D'Absorption De La Molecule De Tellure." Laboratoire Aime, Cotton CNRS II 91405 Orsay, France. 1980. ²Verges, J. "The Laser Induced Fluorescence Spectrum of Te₂ Studied by Fourier Transformation Spectrometry. Physica Scripta. Vol. 25, 338-350, 1982.

A new line list for rovibrational and rotational transitions within the NH X³Σ⁻ ground state has been created, including line intensities in the form of Einstein A and f-values, for all possible bands up to v′=6. The intensities are based on a new dipole moment function (DMF), which has been calculated using the internally contracted MRCI method with an aug-cc-pV6Z basis set. The programs RKR1, LEVEL and PGOPHER were used to calculate line positions and intensities using the most recent spectroscopic observations and the new DMF, and including the rotational dependence on the matrix elements. The Hund's case (b) matrix elements from the LEVEL output have been transformed to the case (a) form required by PGOPHER. Equivalent calculations have been performed for the OH X²Π ground state. This includes a new DMF calculation using the internally contracted MR-ACPF method with an aug-cc-pV6Z basis set. A similar line list has been produced for rovibrational and rotational transitions for all possible transitions up to v′=13.

Precise and accurate positions of the line centers of HCl (v = 2 ← 0) have not been reported for quite some time¹, however, using methane as a transferrable standard, we aim to report line positions to an order of magnitude better than previously characterized and enable the use of HCl as a secondary frequency standard. The line centers for the first overtone of (v =2 ← 0) in the spectral region 5500 - 5900 cm⁻¹ have been measured simultaneously with the 2ν₃ band of methane using the JPL Bruker IFS 125HR. The positions are determined through multispectrum analysis to 1×10⁻⁵ cm⁻¹. Further analysis using the multispectrum fitting software Labfit allows the determination of the self-broadening, self-shift and Dicke narrowing parameters to high precision as well. This potential new standard is compared to the HITRAN 2012 line parameters.

¹ Guelachvilli, G. Opt. Comm. 19, 150-154. (1976).

Using an extended cavity diode laser locked to a frequency comb, the line shape of the P(11) line in the ν₁ + ν₃ combination band of acetylene has been studied as a function of varying concentration of the absorber in nitrogen. Mixture concentrations of 1, 5 and 10% at 296 K and pressures between a few Torr and one atmosphere were made and the measurements analyzed using two different speed-dependent broadening models. These experiments are designed to test the additivity of contributions to pressure broadening and shift in speed-dependent line shape modeling, i.e. whether the lineshape parameters follow partial pressure weighting in the binary mixtures. P(11) is relatively isolated with respect to underlying hot band transitions and neighboring transitions of the same band, but it was found that the accurate positions of underlying hot band transitions were crucial to the successful modeling of the observed line shapes, even though these lines are typically 100-1000 times weaker than P(11) itself and are many Doppler line widths removed from the line center. Positions of the hot band lines quoted in the HITRAN database, which are derived from the analysis of high resolution FTIR spectra, are of the order of 10's of MHz in error. In parallel work, we have measured the positions of many of these lines by saturation dip spectroscopy. Progress in the analysis of the data and the new saturation dip line center measurements will be reported.
Acknowledgments: Work at Brookhaven National Laboratory was carried out under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy and supported by its Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences.

To achieve NASA's strategic scientific mission of monitoring global atmospheric CO₂ at a target precision of 0.25%, we perform laser based measurements and lineshape studies of the reference atmospheric target CO₂ band (20013)←(00001) centered at 2060nm to meet the precision requirements of current (ACOS/GOSAT/TCCON) and future (OCO-2/OCO-3/ASCENDS) remote sensing applications. We utilize a frequency-stabilized cavity ringdown spectrometer, (FS-CRDS), to provide high precision and high spectral resolution for probing non-Voigt lineshape features (Dicke narrowing, speed dependence) of CO₂ currently unaccounted for in databases like HITRAN. We discuss our results for two R-branch lines R(24) and R(30) near 2055nm, which display concurrent collisional narrowing and speed dependence effects.

Use of the Voigt profile with the Lorentz width allowed to vary with the speed of collision has been hampered by the lack of fast accurate algorithms. Such an algorithm has been written assuming a quadratic dependence of the Lorentz width upon the speed of collision that is accurate to one part in 10 000 and is generally only a factor of four or so slower than the equivalent Voigt calculation with the Letchworth and Benner algorithm.¹ The only exception to the accuracy is far from line center near the Doppler limit when the speed dependent parameter is quite large. At this point the spectral line has fallen by at least 17 orders of magnitude from the line center and is generally insignificant. Gauss-Hermite quadrature of third to seventeenth order, Taylor series expansion about precomputed points and spline interpolation are used in the computation of both the real and imaginary parts for various regions.²
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¹Kendra L. Letchworth and D. Chris Benner, JQSRT 107 (2007) 173-192. ²This work was funded by the Jet Propulsion Laboratory and National Science Foundation.

Various atmospheric applications require modeling of infrared absorption by the main atmospheric species in wide ranges of frequencies, pressures and temperatures. For different pressure regimes, different mechanisms are responsible for the observed intensities of vibration-rotation line manifolds, and the structure of the bands changes drastically when going from low to high densities. Therefore, no universal theoretical model exists presently to interpret simultaneously collapsed band-shapes observed at very high pressures and isolated-line shapes recorded in sub-atmospheric regimes. Using CO₂ absorption spectra as an example, we introduce some improvements in the non-Markovian Energy-Corrected Sudden model, developed for high-density spectra of arbitrary tensorial rank¹ and generalized recently to parallel and perpendicular infrared absorption bands², and test the applicability of this approach for the case of nearly Doppler pressure regime via comparisons with recently recorded experimental intensities³.
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¹J.V. Buldyreva and L. Bonamy, Phys. Rev. A 60(1), 370-376 (1999). ²J. Buldyreva and L. Daneshvar, J. Chem. Phys. 139, 164107 (2013). ³L. Daneshvar, T. Földes, J. Buldyreva, J. Vander Auwera, J. Quant. Spectrosc. Radiat. Transfer 2014 (to be submitted).

New data on the IR spectra induced by intermolecular interactions in liquid cryogenic mixtures at T=89 K (O₂ in LAr and LN₂ and binary O₂-Ar solutions in LN₂) are reported.  The induced fundamental bands appear as diffuse pedestals (with FWHH ≈ 100 cm⁻¹) on which weak, paradoxically sharp lines (FWHH ≈ 2 cm⁻¹) develop at the 2326 and 1552 cm⁻¹ frequencies of the free-molecule vibrational transitions in N₂ and O₂, respectively. In LAr and LN₂ these lines were carefully separated and studied at varied O₂ concentrations up to c=0.23 mole fractions (mf). While the 1552 cm⁻¹ line scales as c[O₂]² and thus is induced by the O₂-O₂ interactions in a bulk of cryosolvent (Ar, N₂), the 2326 cm⁻¹ feature varies linearly with c[O₂] and hence is caused by interaction of a guest (O₂) with a vibrating host (N₂).  The impurity induction mechanism was further supported by our data on the binary O₂-Ar solutions in LN₂ recorded at the fixed c[O₂] (0.03 and 0.06 mf) and the varied c[Ar] ≤ 0.2 mf. Both series revealed the same (linear) enhancement of the sharp N₂ line by argon, in an accord with our previous studies of the Ar-LN₂ system¹. The results suggest that the resonance 2326 cm⁻¹ feature is primarily due to the local distortion of the first coordination sphere around a vibrating N₂ by a guest molecule. We also notice that the resonance lines should be due to the dispersion- and overlap-induced dipole moments independent on the rotational degrees of freedom². As our previous studies of the H₂-LNe system showed³, the unusual line sharpness is a conspicuous manifestation of the relative solvent-solute and solute-solute translations dramatically retarded in a liquid by a fast velocity relaxation, an effect directly related to the microscopic-scale diffusion. The collision-induced spectra thus open up new vistas for studies of microscopic liquid dynamics.
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¹W.A. Herrebout, A.A. Stolov, E.J. Sluyts, and B.J. van der Veken, Chem. Phys. Lett. 295, 223 (1998). ²J.E. Bohr and K.L.C. Hunt , J. Chem. Phys. 86, 5441 (1987). ³W. A. Herrebout, B. J. van der Veken, and A. P. Kouzov, J. Chem. Phys. 137, 084509 (2012).