Resonance‐Mediated Below‐Threshold Delayed Photoemission and Non‐Franck–Condon Photodissociation of Cold Oxyallyl Anions

Abstract

AbstractThe photoexcitation of cold oxyallyl anions was studied below the adiabatic detachment threshold at a photon energy of 1.60 eV. Photodetachment was observed through two product channels, delayed electron emission from a long‐lived anionic state and dissociative photodetachment via absorption of a second photon. The former produced stable neutral C3H4O, while the latter resulted in the concerted elimination of CO+C2H4 products. The neutral oxyallyl singlet state has a barrier‐free route to cyclopropanone as well as zwitterionic character with a large charge separation and dipole moment. The role of long‐lived dipole‐bound resonances built on the singlet state below the detachment threshold is discussed. These results provide one of the first observations of delayed photoemission in a small cold molecular radical anion, a consequence of the complex electronic structure of the neutral diradical, and provide an example of resonance‐mediated control of the photodissociation processes.