Bending potentials and geometrical structures for HSiBr, HSiCl, and PH2

Abstract

The bending potentials and geometrical structures are determined for the excited states ¹A'' for HSiBr and HSiCl and for the state ²A ₁ for PH₂. The theoretical model includes only bending motion and rotation about the principle axis of least moment of inertia. Three parameters were used to specify the bending potential and the two bond distances were regarded as parameters. These parameters were adjusted to give a best fit to the spectroscopic data. Corrections were made to include the total rotation and the effects of bond stretching. In the process of making the correction for bond stretching, it was found that the uncertainty could be removed in the previously reported values of v₁ for HSiBr and HSiCl. The resulting bending potentials may be characterized by the equilibrium bond angles θ(subscript e), and the potential barrier heights. For HSiBr, best values are θ(subscript e) = 64.5° and a barrier of 8340 cm⁻¹. The values for HSiCl are θ(subscript e) = 64.8° with a 12,150 cm⁻¹ barrier. For PH₂ θ(subscript e) = 58.1° and the barrier is 6340 cm⁻¹.