Charge Delocalization in Benzene−Naphthalene Hetero-Dimer Cation

Abstract

The electronic spectrum of the benzene-naphthalene hetero-dimer cation is measured in the 400-1200 nm region by the photodissociation spectroscopy. Most intense band at 580 nm is assigned to a local excitation (LE) band of the naphthalene cation chromophore. In addition to this band, an LE band of the benzene cation chromophore of the hetero-dimer is observed at nearly the same position (430 nm) as that of the benzene homo-dimer cation. The observation indicates that the positive charge stays on the benzene molecule in some probability, although the ionization potential of benzene is by 1.10 eV higher than that of naphthalene. The spectrum of the hetero-dimer cation also shows an intermolecular charge transfer (CT) band around 920 nm. On the basis of the position of the CT band as well as the intensity of the LE band relative to that of the homo-dimer, the probability of finding the charge on the benzene molecule is analyzed to be approximately 9 %.

Aromatic Charge Resonance Interaction Probed by Infrared Spectroscopy

“…[9a] As expected, the CR contribution quickly decreases as Ai ncreases in size and as the DIE of the two binding partners increases.T he CR transition was also measured for several A 2 + dimers,including A = benzene, [10] naphthalene, [11] toluene, [12] and their AB + heterodimers. [12,13] However,b ecause the CR transition into the repulsive state is very broad, even in the gas phase,o nly ar ough estimation of the asymmetry in the charge distribution is feasible from its position in AB + dimers.…”

Positive charge distribution in (benzene)1(toleune)2+ and (benzene)2(toluene)1+ studied by photodissociation spectroscopy

“…More recently, we reported the photodissociation spectra of (benzene͒ 1 ͑toluene͒ 1 ϩ and (benzene͒ 1 ͑naphthalene͒ 1 ϩ . 10,16 For both ions, a strong absorption band is observed in the nearinfrared region; these results mean that the CR interaction occurs even in the heterodimer ions with a certain amount of ⌬IE. Neusser et al also presented an energetic scheme for predicting the dissociation pathways of (benzene) 1 (toluene͒ 2 ϩ and (benzene͒ 2 (toluene͒ 1 ϩ ; this scheme explains well the observed fragmentation patterns.…”

“…A simple perturbation theory for a nondegenerate system has been used for analyzing heterodimer ions. 10,16 We apply the same procedure for B 2 T 1 ϩ . Figure 7 depicts an energy level diagram of the species related to B 2 T 1 ϩ .…”

Photoelectron spectroscopy of naphthalene cluster anions

“…[25][26][27][28][29][30][31][32][33][34][35][36] Charge resonance is well known in several aromatic homogeneous dimer cations, where it is characterized by extra stabilization, unique absorption bands, and a charge distribution in which the excess positive charge is evenly distributed over the two aromatic moieties. [25][26][27][28][29][30][31][32][33][34][35][36] Charge resonance is well known in several aromatic homogeneous dimer cations, where it is characterized by extra stabilization, unique absorption bands, and a charge distribution in which the excess positive charge is evenly distributed over the two aromatic moieties.…”