Infrared photodissociation spectroscopy of n-propylbenzene-Ar cluster cations: Charge delocalization between the aromatic ring and the alkyl chain

Infrared -photodissociation spectra of n-propylbenzene-Ar cluster cations h ave been observed for the CH stretching vibrational region. Because of very small perturbations due to the Ar cluster formation, the spectra of the cl uster cations can be practically regarded as those of the corresponding bar e cations. The spectra of the cluster cations were compared with infrared s pectra of neutral n-propylbenzene. It was found that substantially spectral changes take place upon ionization not only for the aromatic CH but also f or the alkyl CH stretching vibrations. This fact indicates that the positiv e charge is not localized in the aromatic ring but is penetrated into the p ropyl side chains.