The Low Lying Electronic States of SiO

Abstract

Perturbations in the A ¹Π state of the isotopic ²⁸Si¹⁶O and ²⁸Si¹⁸O molecules are analyzed. The perturbing states, d ³Δ _r , e ³Σ^-, C ¹Σ^-, and D ¹Δ, are identified and vibrationally assigned. Two independent methods of vibrationally numbering the perturbers, employing isotope shifts and vibrational variation of perturbation matrix elements, respectively, are described in detail and shown to be in complete agreement. Molecular constants for the eight lowest energy electronic states of SiO are presented. Semiempirical and isovalent relationships between spin-orbit and spin-spin constants are discussed.