Add to ORKGThe photodissociation spectra are observed for cluster ions of several aromatic molecules including benzene, toluene, and phenol. Benzene cluster ions, (C6H6)n+ with n = 3-6, retain spectroscopic features characteristic of (C6H6)2+, suggesting that the positive charge is carried by a dimer subunit in (C6H6)n+. The spectrum of (benzene-toluene)+ shows charge resonance bands, which are commonly seen in homo-dimer ions. The resonance interaction is also important in the hetero-dimer ion, despite the difference in the ionization potentials between the two components. Phenol dimer ion exhibits no strong charge resonance band, although it is a homo-dimer ion. Owing to the geometrical constraint of an O-H・・・O hydrogen bond, the two aromatic rings ...