The REMPI spectra of o-, m- and p-bromofluorobenzene and the photodissociation of p-bromofluorobenzene

The vibrations of o-, m- and p-bromofluorobenzene (BrFPh) in the first electronically excited state are studied by (1 + 1) resonance-enhanced two-photon ionization spectroscopy. The observed vibrational bands have been assigned on the basis of comparison with the results from theoretical calculations. The band origins of the S₁ ← S₀ electronic transitions of o-, m- and p-BrFPh, which were influenced by positive resonance effect and negative inductive effect, are found to be 36986.68 cm⁻¹, 36961.48 cm⁻¹ and 36223.20 cm⁻¹ respectively. Meanwhile, the potential barrier height (the energy of the crossing points between the bound S₁ state and a repulsive state relative to the S₁ minimum) of p-BrFPh is determined to be lower than 2815 cm⁻¹ (0.3490 eV) by the REMPI spectra of bromine atom and p-BrFPh molecule.