The Spectrum of Singly Ionized Boron B II

The spectrum of singly ionized boron has been studied by using a sliding spark in vacuum. The wavelength list contains 76 lines in the region 9 660-630 Å, 33 of which have not been observed or identified before. The singlets and triplets have been connected by the assumption that 6 g 1 G and 6 g 3 G have the same term value. The ionization energy has been determined to 202 887.4 ± 1.0 cm -1 by means of the polarization formula for 5 g and 6 g with a theoretical value of the dipole polarizability. The application of the polarization formula to other members of the Be isoelectronic sequence has lead to an increase by 27.2 cm -1 in the ionization limit of C III. The new value is 386 241.0 ± 1.0 cm -1 .