Abstract: According to Frack-Condon principle, the fluorescence and the difference between ground state and the first excited singlet state in bond order, dipole moment, total π electronic energy of benzene, naphthalene, anthracene, and their derivatives have been studied with PPP-SC(β, γ)-CI method on IBM-PC microcomputer. It is found that there are good correlated relationship between fluorescence maxima v^F.L. and fluorescence emission energy △E^F.L., fluorescence quantum yield φ, and total n electronic energy difference between ground state and the first excited singlet state: v^F.L.= 9.5498△E^F.L. + 22.5835(kcm^-1) r = 0.9480 logφ= 0.3583(E_g^x - E_e^x)+ 1.5351 r = 0.9509

Key words: molecular orbit, fluorescence spectra, dipole moment, fluorescence quantum yield, excited state