The permanent dipole moment of TiN and the nuclear magnetic hyperfine structure in its X 2Σ+ and A 2Π electronic states

The permanent dipole moment of TiN in its X 2Σ+ and A 2Σ states has been determined from the complete resolution of the first- and second-order Stark splitting of the Q21(1.5)+R2(0.5) line of the (0,0) band of the A 2Π–X 2Σ+ system. Values of 3.56±0.05 D (2σ) and 4.63±0.04 D (2σ) have been derived for the X and A states respectively, from least-squares fits to plots of Stark splitting vs electric field strength. Electric fields up to 12 kV/cm have been employed avoiding voltage breakdown. The zero-field spectrum shows resolution of the nuclear magnetic hyperfine structure of the 47TiN and 49TiN isotopes. This hyperfine structure is that of the ground X 2Σ+ state only and is shown to follow closely the coupling case bβS. The value of the Fermi contact parameter is −570 MHz which implies a 4s occupation of the 9σ molecular orbital (MO) of 72%. The results are compared with calculated and available experimental values for early first-row transition metal oxides and nitrides.