An investigation of the radiative electron attachment of C₃N through dipole-bound states

Over two hundred molecules have been detected in the interstellar medium (ISM), only six of which are negatively charged.

Although their formation may not yet be well understood, several formation mechanisms have been proposed.

One such pathway is radiative electron attachment (REA), the process by which an electron encounters a neutral molecule and forms a stable anion through photon emission.

Previous calculations have shown that REA rates are too low to explain the observed abundance of CN^-, C₃N^-, and C₅N^-.

REA through weakly bound dipole states, or dipole-bound states (DBSs), has recently been proposed to enhance REA rates and explain the observed abundance of anions in the case of a neutral counterpart with a supercritical dipole moment, such as C₃N.

Although the effects of the rotation and vibration of polar molecules on DBSs have been studied in the past, no prior fully quantum treatment has considered rotation and short-range electron-molecule interactions.

Doing so in the case of C₃N/C₃N^- is the purpose of this study.

The rotationally selected DBSs of C₃N are computed using Close Coupling calculations and an ab initio local model of the interaction potential.

The results are compared to those theoretical results obtained by the simple point-charge-dipole potential and to experimental data.

The rotationally selected REA cross-section through C₃N^- DBSs are then calculated by a quantum approach and are found to still be too small to explain the abundance of this anion in the ISM.