Measurements of relative line strengths in N I multiplets for transition arrays 3s-np (n=3, 4, 5)

Applying the emission method, intensities of 60 spectral lines of neutral nitrogen (N I) belonging to 15 multiplets originating from 3s-np (n=3, 4, 5) transition arrays have been measured. A wall-stabilized arc, operated at atmospheric pressure in helium with some admixture of nitrogen was applied as the excitation source. From measured line intensities, relative line strengths within multiplets have been evaluated. For transitions with Δn=1 and 2, significantly larger discrepancies from LS coupling results are found if compared to transitions 3s-3p (Δn=0). The measured relative line strengths within 3s-3p multiplets are compared with older measurements, recent calculations and with the new data recommended by NIST.