High resolution resonance-enhanced dissociation spectroscopy of chlorobenzene cation prepared by MPI

The well‐resolved absorption spectrum of a large non‐radiative aromatic ion like chlorobenzene has been obtained by the method of resonance‐enhanced multiphoton dissociation (REMPDI). The cations are prepared in the ground electronic state with well‐defined rovibrational energy excess by resonace‐enhanced two‐photon ionization (R2PI). The light of a second laser excites the ions through a (1+1) process into predissociative states which dynamics has been first studied. The wavelength dependence of the fragment ion yield reflects the spectroscopy of the intermediate ionic state reached by the first photon. In this work, we present the completely vibrationally resolved spectrum of the B←X transition of φC1+. For the first time the rotational contour of the vibronic bands of R2PI‐prepared ions has been calculated. The comparison with the experimental band shapes has brought additional arguments for the assignment of the spectral features.