The Spectrum and Term System of Singly Ionized Titanium, Ti II

Abstract

The TiII spectrum has been recorded in the region 1100-11 000 Å. 1240 lines have been classified as transitions between 204 levels of the configurations (3d + 4s)3, 3d2 nl (nl = 5, 6s; 4, 5p; 4, 5d; 4f) and 3d4s4p. Parametric studies including configuration interaction have been carried out for a number of configurations. The ionization energy has been determined to 109 494 ± 20 cm-1.

Oscillator strengths for high-excitation Ti ii from laboratory measurements and calculations

“…a Wavelengths (in vacuum/air below/above 200 nm) deduced from experimental energy levels. b Experimental energy levels taken from Huldt et al (1982) and Saloman (2012). (e) and (o) stand for 'even' and 'odd', respectively.…”

“…In the complex level system of the iron-group elements, with a parent term structure and multiple ionization limits, the strong transitions group in wavelengths due to the similar energy difference between 4s and 4p for the different parent terms (similar promotion energy). In addition, the energy difference between 4p and 5s is similar to that of 4s and Huldt et al (1982). b All levels were excited using the second harmonic of the dye laser.…”

“…1.08 a 0 . Radial integrals of the 3d 3 , 3d 2 4s, 3d 2 5s, 3d 2 4d, 3d4s 2 , 3d 2 4p and 3d4s4p, considered as free parameters, were then adjusted with a well-established least-squares optimization program minimizing the discrepancies between the calculated Hamiltonian eigenvalues and the experimental energy levels taken from Huldt et al (1982). More precisely, the average energies (E av ), the electrostatic direct (F k ) and exchange (G k ) integrals, the spin-orbit (ζ nl ) and effective interaction parameters (α and β) were allowed to vary during the fitting process.…”

“…The lowest odd configurations are 3d 2 4p and 3d4s4p spanning the energy interval from 29 500 to 59 500 cm −1 (Huldt et al 1982). Transitions between these configurations give rise to the most intense spectral lines in Ti II, and have been the subject of most previous experimental and theoretical investigations.…”

The peculiar A star HD 43819 - A photographic region line-identification study

“…Till: (Huldt et al 1982): Many strong, moderate strength, and weak lines are seen. The wavelengths and intensity are from the additional source whenever possible.…”