Abstract
The high resolution infrared spectrum of 123SbD3 has been recorded in the 20–350 cm−1 range and in the regions of the ν1, ν3 and ν2, ν4 fundamental bands centred at 1350 and 600 cm−1, respectively. Splitting of the K′′ = 3, 6 lines have been observed both in the rotation and ro-vibration spectra. A large number of ‘perturbation allowed‘ transitions with selection rules Δ(k −l) = ± 3, ± 6, and ± 9 have been identified in all fundamental bands. Accurate ground state molecular parameters have been determined by means of a simultaneous fit of the rotational transitions and about 12 000 ground state combination differences from the infrared bands. The A and B reductions of the rotational Hamiltonian provided almost equivalent results. The molecular parameters of the ν i = 1 (i = 1 − 4) states were obtained as a result of the simultaneous analysis of the ν1 (A1)/ν3 (E) stretching and of the ν2 (A1)/ν4 (E) bending dyads. In fact, the corresponding excited states are affected by strong perturbations due to rovibrational interactions of Coriolis and k-type that have been treated explicitly in the model adopted for the analysis. Improved effective ground state and equilibrium geometries were determined for the molecule and compared to those of 123SbH3. Ab initio calculations at the coupled cluster CCSD(T) level with an energy-consistent large-core pseudopotential and large basis sets were carried out to determine the equilibrium structure, the anharmonic force field, and the associated spectroscopic constants of 123SbH3 and 123SbD3. The theoretical results are in good agreement with the experimental data.
Acknowledgements
This work was carried out within the frame of the SPHERS network (HPRN-CT-2000-00022). We thank the EC for financial support. E.C., G.D.L., and L.F. acknowledge the financial support of the Università di Bologna and of the Ministero dell’Istruzione, dell’Università e della Ricerca.
Notes
Note that in our previous work Citation[28] the calculated Coriolis coupling constants ζ13 y and ζ24 y in AsH3, 121SbH3, 123SbH3, and BiH3 were erroneously assigned to be positive. Using the correct negative sign for these constants, the predicted sense of the intensity perturbations Citation[28] is reversed and is then in agreement with the present study.