Electronic spectroscopy and electronic structure of diatomic TiFe

Diatomic TiFe, a 12 valence electron molecule that is isoelectronic with Cr-2, has been spectroscopically investigated for the first time. In addition, the first computational study that includes the ground and excited electronic states is reported. Like Cr-2, TiFe has a (1)Sigma(+) ground state that is dominated by the 1 sigma(2) 2 sigma(2) 1 pi(4) 1 delta(4) configuration. Rotationally resolved spectroscopy has established a ground state bond length of 1.7024(3) angstrom, quite similar to that found for Cr-2 (r(0) = 1.6858 angstrom). Evidently, TiFe exhibits a high degree of multiple bonding. The vibronic spectrum is highly congested and intense to the blue of 20 000 cm(-1), while two extremely weak band systems, the [15.9](3)Pi(1) <- X (1)Sigma(+) and [16.2](3)Pi(0+) <- X E-1(+) systems, are found in the 16 000-18 500 cm(-1) region. The bond lengths, obtained by inversion of the B-e' values, and vibrational frequencies of the two upper states are nearly identical: 1.886 angstrom and 344 cm(-1) for [15.9](3)Pi(1) and 1.884 angstrom and 349 cm(-1) for [16.2](3) Pi(0+). The measured spin-orbit splitting of the (3)Pi state is consistent with its assignment to the 1 sigma(2) 2 sigma(2) 1 pi(4) 1 delta(3) 2 pi(1) configuration, as is also found in the ab initio calculations. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4738958]