The NII spectrum of the Orion Nebula
  The predicted emission spectrum of NII is compared with observations of permitted lines in the Orion nebula. Conventional nebular models show that the intensities of the more intense lines can be explained by fluorescence of starlight absorption with a N abundance that is consistent with forbidden lines. Lines excited mostly by recombination on the other hand predict high N abundances. The effects of stellar and nebular parameters and of the atomic data on the predicted intensities are examined. 
Vladimir Escalante and Christophe Morisset