The absorption spectrum of B I in the 1350–1900-Å region has been photographed in the third and fourth orders of a 6.6-m spectrograph. The 2s2 2p2Pº-2s2nd2D and 2s2 2p2Pº-2s2ns2S series were observed to n = 39 and n = 10, respectively, leading to the assignment of 35 new term levels in B I. Extrapolation of the nd2D series yields 66 928.0±0.2 cm-1, in agreement with the best previously published value for the ionization potential of boron.
C. M. Brown, S. G. Tilford, and M. L. Ginter, "Absorption spectrum of B I in the 1350–1900-Å region," J. Opt. Soc. Am. 64, 877-879 (1974)