Naphthalene spectroscopy excitation energies

The naphthalene cation has been studied by absorption spectroscopy in solutions [154,155], glasses [156-159], and matrices [160]. Gas-phase data stem from PES [161,162] and multiphoton dissociation [163,164] spectra. Recently, the 180- to 900-nm absorption spectrum of naphthalene formed by photoionization in a neon matrix has been reinvestigated [165]. These experiments show seven progressions, with peak maxima at 1.84, 2.72, 3.29, 4.06, 4.49, 5.07, and 5.57 eV. The excitation energies calculated by Schutz et al. for the cation geometry are shown in Table XIV. They are in agreement with experiment. The largest deviation amounts to 0.13 eV (2 B2g). Table XIV also shows the predicted PES, which matches experiment. 

Time dependent fluorescence depolarization is influenced by the exciton annihilation which occurs in confined molecular domains . Photoemission results from singlet exciton fusion as shown by the excitation intensity dependence which occurs in anthracene crystals. Reabsorption of excitonic luminescence is an effect which has been shown to occur in pyrene crystals. The dynamics of exciton trapping in p-methylnaphthalene doped naphthalene crystals involves phonon assisted detrapping of electronic energy. Ps time resolved spectroscopy was the experimental technique used in this work. 

Itagaki et al [76] have proposed that the decay kinetics observed for fluid solutions of poly(l-methoxy-4-vinylnaphthalene) (PMVN) may be explained in terms of two excimer species in addition to excited monomer. The proposal is based on variations in steady-state l,3-di(4-methoxy-1-naphthyl)propane (BMP) [77,78], presumes that the lower energy excimer comprises the normal structure with fully overlapped aromatic rings, whereas the second excimer is thought to comprise a partially overlapped structure. Steady state spectroscopy indicated a reasonable degree of evidence that three excited state species do indeed exist in the sterically hindered naphthalene systems. However the spectral and numerical deconvolution procedures adopted make the separation of intensity components used in the kinetic analysis, necessary for excited state assignment, rather optimistic. 

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