High-temperature spectra of the PNO molecule based on robust first-principles methods

Area of Science:

• Astrochemistry
• Computational Quantum Chemistry
• Spectroscopy

Background:

• The PNO molecule is significant in the interstellar medium.
• Spectroscopic data is crucial for identifying interstellar species.
• Previous spectroscopic data for PNO was limited.

Purpose of the Study:

• To create the first extensive line list for PNO (X ¹ Σ ⁺).
• To provide accurate spectroscopic parameters for PNO detection.
• To aid in the characterization of PNO in astronomical observations.

Main Methods:

• Utilized first-principles calculations to construct potential energy and dipole moment surfaces.
• Employed variational nuclear motion calculations in TROVE.
• Incorporated a J-dependent Coriolis-decoupled Hamiltonian and considered l-type doubling.

Main Results:

• Generated a line list with 5.87 billion transitions from 3.61 million energy levels (J up to 200).
• Calculated the PNO spectrum from 0 to 6000 cm^-1 for temperatures below 3000 K.
• Observed good agreement between calculated millimetre wave spectra and experimental data.
• Identified universal and complex Fermi resonance effects impacting spectral intensities.

Conclusions:

• The presented line list is valuable for spectroscopic characterization of PNO.
• This data facilitates the potential astronomical detection of PNO.
• The findings are particularly relevant for high-temperature interstellar environments.