343 research outputs found

    ExoMol molecular line lists XXX: a complete high-accuracy line list for water

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    A new line list for H2_216^{16}O is presented. This line list, which is called POKAZATEL, includes transitions between rotation-vibrational energy levels up to 41000 cm1^{-1} in energy and is the most complete to date. The potential energy surface (PES) used for producing the line list was obtained by fitting a high-quality ab initio PES to experimental energy levels with energies of 41000 cm1^{-1} and for rotational excitations up to J=5J=5. The final line list comprises all energy levels up to 41000 cm1^{-1} and rotational angular momentum JJ up to 72. An accurate ab initio dipole moment surface (DMS) was used for the calculation of line intensities and reproduces high-precision experimental intensity data with an accuracy close to 1 %. The final line list uses empirical energy levels whenever they are available, to ensure that line positions are reproduced as accurately as possible. The POKAZATEL line list contains over 5 billion transitions and is available from the ExoMol website (www.exomol.com) and the CDS database

    The properties of coke breeze briquettes produced by ram briquetting

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    The paper reports on the results of briquetting coke breeze with a binder in a closed cylindrical press-die. Liquid glass is used as a binder. Approximating curves for the "compaction ratio vs. compaction pressure" dependences are plotted from experimental data. The mechanical properties of the briquettes are determined, namely, drop damage resistance and breaking stress. The results are presented as approximating dependences in the form of a power function. © 2017 Author(s)

    A room temperature CO2_2 line list with ab initio computed intensities

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    Atmospheric carbon dioxide concentrations are being closely monitored by remote sensing experiments which rely on knowing line intensities with an uncertainty of 0.5% or better. We report a theoretical study providing rotation-vibration line intensities substantially within the required accuracy based on the use of a highly accurate {\it ab initio} dipole moment surface (DMS). The theoretical model developed is used to compute CO2_2 intensities with uncertainty estimates informed by cross comparing line lists calculated using pairs of potential energy surfaces (PES) and DMS's of similar high quality. This yields lines sensitivities which are utilized in reliability analysis of our results. The final outcome is compared to recent accurate measurements as well as the HITRAN2012 database. Transition frequencies are obtained from effective Hamiltonian calculations to produce a comprehensive line list covering all 12^{12}C16^{16}O2_2 transitions below 8000 cm1^{-1} and stronger than 1030^{-30} cm / molecule at T=296T=296~

    Accurate prediction of H<sub>3</sub>O<sup>+</sup> and D<sub>3</sub>O<sup>+</sup> sensitivity coefficients to probe a variable proton-to-electron mass ratio

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    The mass sensitivity of the vibration–rotation–inversion transitions of H316O+, H318O+, and D316O+ is investigated variationally using the nuclear motion program TROVE (Yurchenko, Thiel & Jensen). The calculations utilize new high-level ab initio potential energy and dipole moment surfaces. Along with the mass dependence, frequency data and Einstein A coefficients are computed for all transitions probed. Particular attention is paid to the Δ|k| = 3 and Δ|k − l| = 3 transitions comprising the accidentally coinciding |J, K = 0, v2 = 0+〉 and |J, K = 3, v2 = 0−〉 rotation–inversion energy levels. The newly computed probes exhibit sensitivities comparable to their ammonia and methanol counterparts, thus demonstrating their potential for testing the cosmological stability of the proton-to-electron mass ratio. The theoretical TROVE results are in close agreement with sensitivities obtained using the non-rigid and rigid inverter approximate models, confirming that the ab initio theory used in the present study is adequate
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