Radiative electron attachment to rotating C$_3$N through dipole-bound states

TL;DR

This study uses advanced ab initio methods to investigate how large dipole moments influence electron attachment in rotating C$_3$N$, successfully reproducing observed dipole-bound states and calculating attachment cross sections relevant to astrochemistry.

Contribution

It provides the first accurate theoretical analysis of radiative electron attachment to rotating C$_3$N, including dipole-bound states and cross sections, clarifying formation mechanisms in space.

Findings

Theory reproduces observed dipole-bound states in C$_3$N$^-$.

Calculated attachment cross section is too small for interstellar formation.

Suggests alternative formation processes for C$_3$N$^-$ in space.

Abstract

The role of a large dipole moment in rotating neutral molecules interacting with low-energy electrons is studied using an accurate {\it ab initio} approach accounting for electronic and rotational degrees of freedom. It is found that theory can reproduce weakly-bound (dipole-bound) states observed in a recent photodetachment experiment with C$_3$N$^-$ [Phys. Rev. Lett. {\bf 127}, 043001 (2021)]. Using a similar level of theory, the cross section for radiative electron attachment to the C$_3$N molecule, forming the dipole-bound states, was determined. The obtained cross section is too small to explain the formation of C$_3$N$^-$ in the interstellar medium, suggesting that it is likely formed by a different process.