Excited state (E = 174.4 cm⁻¹) to resonance state column density ratio of N III vs. the electron number density (blue curve) from the Chianti atomic database for T = 16 000 K. The measured ratio is shown by the red dot, and the accompanying error bars are shown by the vertical red lines. The 174.4 cm⁻¹ transition in N III arises from the ²P_3/2  →  ²P_1/2 transition within this ion.