Related Experiment Video
Updated: Dec 10, 2025

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F−
Published on: July 27, 2018
Observation of a π-Type Dipole-Bound State in Molecular Anions
Dao-Fu Yuan1, Yuan Liu1, Chen-Hui Qian1
1Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA.
Abstract:
We report the observation of a π-type dipole-bound state (π-DBS) in cryogenically cooled deprotonated 9-anthrol molecular anions (9AT^{-}) by resonant two-photon photoelectron imaging. A DBS is observed 191 cm^{-1} (0.0237 eV) below the detachment threshold, and the existence of the π-DBS is revealed by a distinct (s+d)-wave photoelectron angular distribution. The π-DBS is stabilized by the large anisotropic in-plane polarizability of 9AT. The population of the dipole-forbidden π-DBS is proposed to be via a nonadiabatic coupling with the dipole-allowed σ-type DBS mediated by molecular rotations.
Related Concept Videos
Molecular Geometry and Dipole Moments
Molecular Orbital Theory II
Molecular Shape and Polarity
Bond Polarity, Dipole Moment, and Percent Ionic Character
π Molecular Orbitals of the Allyl Cation and Anion
MO Theory and Covalent Bonding

