Term analysis of the spectrum of neutral neptunium (Np I)

We have measured approximately 6096 Np wavelengths with the 9 m Paschen--Runge spectrograph at Argonne and the Fourier transform facilities at Aime Cotton, of which 40% have been classified as transitions between 130 even levels and 329 odd levels. Most of the even levels and half of the odd levels have been identified by hyperfine structure and Zeeman data. The ground configuration is 5f4 6d7s2; the next configuration, 5f5 7s2, starts at 2831 cm-1. The low levels of 5f4 6d2 7s, 5f3 6d2 7s2, and 5f4 6d7s7p have been identified, and parameter fits have been made for 5f4 6d7s2 and 5f4 7s2 7p