Some Atomic Parameters Pertinent to Studies of Nebular Ionized Plasmas

In order to predict emission line and continuum intensities and assess plasma diagnostics for gaseous nebulae, it is necessary to have accurate atomic parameters. In some Instances the requirements for accuracy are very severe. A variety of data is required:1)Coefficients of continuous absorption;2)Direct and dielectronic recombination coefficients;3)Transition probabilities for permitted lines, so we can accurately predict both recombination line intensities and fluorescent phenomena (e.g., OI λ8446);4)Transition probabilities for forbidden and intercombination lines;5)Collision cross sections for levels which give rise to: a)resonance transitions,b)intercombination lines,c)forbidden lines;6)Charge-exchange cross sections.