The spectrum of optically allowed transitions from the 3p⁶3d ground state of Ti IV

Recent experiments on the photoionization of Ti IV (Schippers S et al 2004 J. Phys. B: At. Mol. Opt. Phys. 37 L209–16) and the photorecombination of Ti V (Schippers S et al 1998 J. Phys. B: At. Mol. Opt. Phys. 31 4873–86) have obtained the excitation energies and spontaneous transition probabilities (A-values) for a number of the 3p⁵3d² and 3p⁵3d4s autoionization states of Ti IV. The direct measurements of the spectrum of Ti IV excited in a vacuum spark (Ryabtsev A N et al 2005 Opt. Spectrosc. 98 519–27) have provided a more complete list of these excitation energies and the A-values for J–J transitions of these excited states to the 3p⁶3d ground state. This paper presents ab initio calculations for the transition energies and A-values between individual J levels of the ground state of Ti IV and the J levels for both the bound (3d)⁶nl states and the bound and resonance states 3p⁵3d² and 3p⁵3d4s. The calculations were carried with configuration interaction wavefunctions and relativistic effects were included using the Breit–Pauli approximation. Generally there is good agreement between the calculated transition energies and all the experimental transition energies. There are considerable differences between the A-values obtained by the different experimental groups and the agreement between the theoretical and experimental A-values is variable.