Autodetachment of diatomic carbon anions from long-lived high-rotation quartet states

TL;DR

This study investigates the autodetachment process of highly excited diatomic carbon anions, revealing that high rotational states stabilize these ions and influence their decay pathways, with theoretical calculations supporting experimental observations.

Contribution

The paper identifies high rotation as a stabilizing factor against autodetachment in C$_2{}^{-}$ ions and provides a theoretical model explaining the decay dynamics.

Findings

High rotation stabilizes C$_2{}^{-}$ ions against autodetachment.

Time constants for autodetachment are calculated using a non-local resonance model.

Theoretical results explain experimental observations for low rotation levels.

Abstract

Highly excited C$_2{}^{-}$ ions prominently feature electron detachment at a mean decay time near 3 milliseconds with hitherto unexplained origin. Considering various sources of unimolecular decay, we attribute the signal to the electronic C$^4\Sigma^+_u$ state. Quartet C$_2{}^{-}$ levels are found to be stabilized against autodetachment by high rotation. Time constants of their rotationally assisted autodetachment into levels opening energetically at lower rotation are calculated by a theory based on the non-local resonance model. For some final levels of significantly less rotation the results conclusively explain the puzzling observations.