Rotational spectra, potential function, Born-Oppenheimer breakdown and magnetic shielding of SiSe and SiTe

The pure rotational spectra of 18 isotopic species of SiSe (8) and SiTe (10) have been measured in then X-1 Sigma(+) electronic state with a pulsed-jet resonator Fourier transform microwave spectrometer. The molecules were prepared by a combined DC discharge/laser ablation technique and stabilised in a supersonic jet of Ar.. Global multi-isotopologue analyses yielded spectroscopic Dunham parameters Y-01, Y-11,Y- Y-21, Y-31 and Y-02 for both species, as well as effective Born-Oppenheimer breakdown (BOB) coefficients delta(01) for Si, Se and Te. A direct fit of the same data sets to an appropriate radial Hamiltonian yielded analytic potential energy functions and BOB radial functions for the X-1 Sigma(+) electronic state of both SiSe and SiTe. Additionally, the magnetic hyperfine interactions produced by the uneven mass number A nuclei Si-29, Se-77 and Te-125 were observed, yielding first determinations of the corresponding nuclear spin-rotation Coupling constants. (C) 2008 Elsevier Inc. All rights reserved.