Determination of the vibrationless level of Sn states of chlorobenzene by double resonance multiphoton ionization photoelectron spectroscopy. Evidence of IVR within these states Original Research Article

We report the study of several higher excited Sn(n > 2) valence states of chlorobenzene observed by double resonance multiphoton ionization photoelectron spectroscopy in the 56000–67000 cm−1 region. The simultaneous measurement of the kinetic energy of the electrons and of the corresponding absorption spectrum enabled to determine the respective vibrationless level of these states (55120, 56600, 61100 and 62210 cm−1) and to distinguish direct ionization for Rydberg states from ionization after IVR of the initially excited level for valence states. The onset of IVR mechanism, at about 1000 cm−1 internal energy, was determined from double resonance absorption spectroscopy.