Molecular ion spectroscopy: Resonance-enhanced multiphoton dissociation spectra of the fluorobenzene cation

Abstract

We present a well-resolved spectrum of the dipole-forbidden B (B 2)← X (B 1) transition of the fluorobenzene radical cation. Using a two-color version of our technique of resonance-enhanced multiphoton dissociation spectroscopy (REMPDS), we obtained the first vibrationally resolved spectrum for this molecular ion. Fluorobenzene ions were prepared in the ionic X state by multiphoton ionization; the resulting vibrational population was probed by photoelectron spectroscopy. The most prominent bands of the B ← X transition were assigned to combinations of the inducing mode ν 16a with a progression of ν 6a.