The spectrum and term system of neonlike titanium, Ti XIII

New observations of the spectrum of Ne-like titanium, Ti XIII, in the region 17–552 Å together with previously reported data have been used in an extended study of the Ti XIII term system. The levels of the excited configurations 2s 2 2p 5 3s, 3p, 3d, 4s, 4p, 4d, 4f, 5d, 5f, 5g, 6g and 6h are reported. Most of the levels were established from the observations, while some were derived from energy parameters fitted to the observed levels. Observation of the hydrogenic levels has enabled a determination of the ionization energy by means of the polarization formula. The ionization energy is 6 353 000 ± 300 cm −1 .