MILLIMETER AND SUB-MILLIMETER-WAVE SPECTRUM OF SELENIUM DIOXIDE, SeO₂
Subject and Purpose. The work is aimed at investigating the spectra of the ground-state and a few of the excited vibrational states for the main isotopologues of the selenium dioxide molecule, SeO₂, in order to provide a reliable basis for its further search in the interstellar medium. Method and...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
National Academy of Sciences of Ukraine, Institute of Radio Astronomy
2025-06-01
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| Series: | Radio Physics and Radio Astronomy |
| Subjects: | |
| Online Access: | http://rpra-journal.org.ua/index.php/ra/article/view/1471/pdf |
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| Summary: | Subject and Purpose. The work is aimed at investigating the spectra of the ground-state and a few of the excited vibrational states for the main isotopologues of the selenium dioxide molecule, SeO₂, in order to provide a reliable basis for its further search in the interstellar medium.
Method and methodology. The method is based on real-life measurements and onward analysis of the microwave rotational spectrum of the SeO₂ molecule. The measurements are carried out with an automated millimeter wave spectrometer of the Institute of Radio Astronomy of the NAS of Ukraine, (Kharkiv, Ukraine), and the submillimeter-wave spectrometer of the V. N. Karazin Kharkiv National University (Kharkiv, Ukraine).
Results. The measurements were carried out within a range between 70GHz and 500 GHz, where frequencies of about 650 rotational transitions were measured. Most of these belong to the ⁷⁶SeO₂ , ⁷⁷SeO₂, ⁷⁸SeO₂ , ⁸⁰SeO₂ , and ⁸²SeO₂ molecules in their respective vibrational ground states. The rest of the lines can be assigned to isotopic species of the 76SeO₂ , ⁷⁷SeO₂ , ⁷⁸SeO₂ , ⁸⁰SeO₂ , and ⁸²SeO₂ molecules in their excited vibrational state ν₂ = 1, while in the case of ⁸⁰SeO₂ in the excited state ν₂ = 2 as well. In addition, tentative assignments have been suggested for 10 transitions in the ground state isotopic species of ⁷⁷SeO₂.
Conclusions. The transitions between states characterized by quantum numbers J up to 70 and quantum numbers Kɑ up to 19, embracing the ground-state and first-, and second-order excited vibrational states of the ⁷⁴SeO₂ , ⁷⁶SeO₂ , ⁷⁷SeO₂ , ⁷⁸SeO₂ , ⁸⁰SeO₂ , and ⁸²SeO₂ molecules have been identified. Based on these assigned transitions, significantly improved estimates have been obtained for sets of rotational and centrifugal distortion constants, including octicones, as well as for A-reduced Watson’s Hamiltonian in the Ir coordinate representation. The parameter sets obtained provide for reliable predictions for possible future astronomical search of the most abundant isotopic species of the SeO₂ molecule. |
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| ISSN: | 1027-9636 2415-7007 |