Electronic states and spectroscopic properties of GeSi

Electronic structure and spectroscopy of the GeSi molecule have been investigated by performing ab initio based multireference configuration interaction calculations. Potential energy curves of 29 Lambda-S states of singlet, triplet, and quintet spin multiplicities have been constructed. Spectroscopic constants of 24 bound states within 36 000 cm(-1) are reported and compared with the available data. The calculated dissociation energy of GeSi in the ground state is 2.80 eV. Effects of the spin-orbit coupling on the spectroscopic properties of the molecule have been found to be small. However, the computed zero-field-splitting of the ground state compares well with the earlier prediction. Transitions such as 2(3)Sigma(-)-X-3 Sigma(-). 3(3)Sigma(-)-X-3 Sigma(-), 4(3)Pi-A(3)Pi, 5(3)Pi-A(3)Pi etc. are relatively strong. Radiative lifetimes for several dipole allowed and spin-forbidden transitions are calculated. The estimated lifetimes of the 2(3)Sigma(-), 3(3)Sigma(-), and 5(3)Pi states are about 109, 33, and 62 ns, respectively. Dipole moments of most of the low-lying states of GeSi are also reported. (C) 2008 Elsevier Inc. All rights reserved.