Low-lying Dipole Resonances in FeCN−: A Viable Formation Pathway for FeCN− in Space

Abstract

Abstract A low-lying resonance in FeCN− anion was identified through abrupt changes in the spectral dependence of the photoelectron angular distribution. Non-Franck–Condon transitions from the resonance to the neutral FeCN (4Δ), and the corresponding photoelectron angular distributions revealed that the resonance is a dipole scattering state. Significant thermionic electron emission was observed in the resonant photoelectron spectra, indicating a strong coupling of the resonance with the ground state of this triatomic anion and its competition over autodetachment. This low-lying resonance is identified to be an efficient pathway for the formation of FeCN− anion in the outer envelope of IRC+10216. The results in general reveal formation pathways in space for anions with low-lying resonances and large permanent dipole moment.