Dipole Moment of the First Excited π* ← π State of Fluorobenzene

Abstract

A Stark effect is observed in the rotational fine structure of the 0–0 band of the lowest-lying singlet π* ← π state of fluorobenzene. Splittings are found in both P and R branches. This enables us to determine the excited-state dipole moment to be μ′ = 1.96 ± 0.07 D. This result is discussed in relation to previous measurements on substituted benzenes, and it is shown that the previously observed correlation between structure and dipole moment for excited states also extends to fluorobenzene.