Negative ion properties of fluoranil, chloranil, and bromanil: Electron affinities

Abstract

Bound and excited negative ion states of p‐fluoranil (FA), p‐chloranil (CA), and p‐bromanil (BA) are studied from experiments involving collisions of electrons, Na, K, and Cs beams with FA, CA, AND BA. Reaction thresholds for producing FA⁻, CA⁻, and BA⁻ are determined as a function of the temperature of the target molecules. The electron affinities corresponding to 0 °K were measured to be 2.92±0.2 eV for FA, 2.76±0.2 eV for CA, and 2.44±0.2 eV for BA. FA, CA, and BA attach ∼ 0 eV electrons and FA attaches 0.5 eV electrons to form metastable parent negative ions with lifetimes in the millisecond range. These lifetimes are a function of the electron energy. Dissociative and nondissociative resonances observed via electron attachment to p‐benzoquinone (PBQ) and the ’’anils’’ are correlated with the optically determined ²B_3g′, ²B_1u, and ²A_u states of PBQ⁻ and the anion radicals of several substituted quinones.