Theoretical emission line ratios for [Fe III] and [Fe VII] applicable to the optical and infrared spectra of gaseous nebulae

Recent calculations of electron impact excitation rates and Einstein A-coef ficients for transitions among the 3d(6) levels of Fe III and among the 3d( 2) levels of Fe VII are used to derive theoretical emission line ratios app licable to the optical and infrared spectra of gaseous nebulae. Results for [Fe III] are generated for electron temperatures T-e = 7,000-20,000 K and densities N-e = 10(2)-10(8) cm(-3), whereas those for [Fe VII] are provided for T-e = 10,000-30,000 K and N-e = 10(2)-10(8) cm(-3). The theoretical li ne ratios are significantly different in some instances from earlier calcul ations and resolve discrepancies between theory and observation found for t he planetary nebulae IC 4997 and NGC 7027.