Photoinduced Penning-type ionization in collisional Rydberg carbon-molecules complexes: Energetic plausibility under...

Area of Science:

• Astrochemistry
• Quantum Chemistry
• Spectroscopy

Background:

• Diffuse interstellar bands (DIBs) are observed astrophysical absorption features.
• High-n Rydberg carbon atoms (C*s) are abundant in interstellar environments.
• Small molecules like carbon monoxide (CO) and hydroxyl radical (OH) are also prevalent.

Purpose of the Study:

• To assess the energetic plausibility of photoinduced Penning-type ionization in collisional complexes between C*s and interstellar molecules.
• To investigate the potential contribution of these complexes to observed diffuse interstellar bands.

Main Methods:

• Calculated transition wavelengths for C* + CO and C* + OH collisional complexes using experimental ionization potentials and spectroscopic constants.
• Compared calculated wavelengths with known diffuse interstellar band observations.

Main Results:

• Predicted transition wavelengths for C* + CO complexes match observed DIBs at 450.23 nm (v=0) and 498.33 nm (v=1).
• Predicted transition wavelengths for C* + OH complexes match observed DIBs at 705.57 nm (2Π3/2) and 712.56 nm (2Π1/2).
• These spectral matches suggest C* collisional complexes contribute to selected astrophysical absorption features.

Conclusions:

• Rydberg-mediated interactions in C* collisional complexes with CO and OH provide an energetically plausible explanation for specific DIBs.
• This framework is particularly relevant in interstellar regions with C+ recombination and coexisting CO or OH.
• Further theoretical and observational studies are needed to confirm the role of these transient complexes in interstellar chemistry.