Charge delocalization of radical cations formed in naphthalene monomer, dyad, and triad molecules in solutions was studied by near-IR transient absorption spectroscopy. The triad molecules were 1,5-di(2-naphthyl)-3-phenylpentane (NBN), 1,3-di(2-naphthyl)-5-phenylpentane (NNB), and 1,3,5-tri(2-naphthyl)pentane (NNN). Charge resonance bands were observed around 900 nm for NBN, 1250 nm for NNB, and 1300 nm for NNN. The absorption bands for the triad molecules were ascribed to hetero-dimer cation of naphthalene and benzene, dimer radical cation, and trimer radical cation, respectively. (C) 2003 Elsevier Science B.V. All rights reserved.