<p>Studying the rovibrational spectra of hydrogen cyanide (HCN) has become increasingly relevant due to growing concerns about the molecule’s environmental and health risks and its special role in astronomy. Empirical rovibrational energy levels are determined based on the MARVEL (Measured Active Rotational-Vibrational Energy Levels) protocol for H<sup>12</sup>C<sup>14</sup>N, the most abundant HCN&#xa0;isotopologue. The spectroscopic analysis is based on 23 225 measured transitions, of which 14 728 are unique, collected from 39 literature sources. In contrast to most previous MARVEL studies, which utilized a very large number of experimental sources, for H<sup>12</sup>C<sup>14</sup>N 70 % of the measured transitions are contained in two literature sources. The experimental transitions used in the final MARVEL analysis form a spectroscopic network with a single principal and just a few floating components, but a large number of orphans. To ensure the reliability of the final empirical rovibrational energy level set, the final MARVEL analysis involved artificial transitions determined from accurately fitted effective Hamiltonian models. The transitions collected and validated span the spectral range of 0&#xa0;−&#xa0;13 018 cm<sup>−1</sup>. Altogether 5564 empirical rovibrational energies, which make ca. 30% of states determined through effective Hamiltonian fits for the [H,C,N] system, with an average expanded uncertainty of 0.006 cm<sup>−1</sup>, are obtained for H<sup>12</sup>C<sup>14</sup>N; they are associated with 174 vibrational bands. A comparison of the empirical rovibrational energy levels obtained in this study, and the transitions that can be generated from them, with those in the composite experimental/empirical/first-principles-computed HITRAN2020, ExoMol, and MOMeNT-90 datasets reveals excellent overall agreement. Nevertheless, there are particularly notable exceptions in the case of HITRAN2020, for which there appear to be problems with the published labels of many lines.</p>

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Measured active rotational-vibrational energy levels (MARVEL) analysis of high-resolution rovibrational spectra of H12C14N

  • Waed O. H. Al-Nashash,
  • Ala’a A. A. Azzam,
  • Sana A. E. Abzakh,
  • Dunia Alatoom,
  • Mohammad Taha I. Ibrahim,
  • Jonathan Tennyson,
  • Tibor Furtenbacher,
  • Attila G. Császár

摘要

Studying the rovibrational spectra of hydrogen cyanide (HCN) has become increasingly relevant due to growing concerns about the molecule’s environmental and health risks and its special role in astronomy. Empirical rovibrational energy levels are determined based on the MARVEL (Measured Active Rotational-Vibrational Energy Levels) protocol for H12C14N, the most abundant HCN isotopologue. The spectroscopic analysis is based on 23 225 measured transitions, of which 14 728 are unique, collected from 39 literature sources. In contrast to most previous MARVEL studies, which utilized a very large number of experimental sources, for H12C14N 70 % of the measured transitions are contained in two literature sources. The experimental transitions used in the final MARVEL analysis form a spectroscopic network with a single principal and just a few floating components, but a large number of orphans. To ensure the reliability of the final empirical rovibrational energy level set, the final MARVEL analysis involved artificial transitions determined from accurately fitted effective Hamiltonian models. The transitions collected and validated span the spectral range of 0 − 13 018 cm−1. Altogether 5564 empirical rovibrational energies, which make ca. 30% of states determined through effective Hamiltonian fits for the [H,C,N] system, with an average expanded uncertainty of 0.006 cm−1, are obtained for H12C14N; they are associated with 174 vibrational bands. A comparison of the empirical rovibrational energy levels obtained in this study, and the transitions that can be generated from them, with those in the composite experimental/empirical/first-principles-computed HITRAN2020, ExoMol, and MOMeNT-90 datasets reveals excellent overall agreement. Nevertheless, there are particularly notable exceptions in the case of HITRAN2020, for which there appear to be problems with the published labels of many lines.