NUCLEAR HYPERFINE INTERACTIONS IN SPHERICAL TOPS IN THEIR GROUND ELECTRONIC AND VIBRONIC STATES

The nuclear hyperfine Hamiltonian for XY4 and XY6 spherical-top molecules, in their ground electronic and vibronic states, is constructed by a tensor method similar to that used in vibrational studies, and is given by a linear combination of invariant tensor products in the group (F)O(3) × G (G = Td or Oh). The predominant interaction operators (spinrotation, spin-spin, Zeeman, and shielding) are explicitly given. This method allows one to obtain general expressions for the matrix elements; formulas are determined in the zero-, low-, and high-field limits. These are applied to the calculation of the diagonal contributions to hyperfine energies of XY4 and XY6 molecules; atom X is spinless and atoms Y have spin 1 2. A detailed comparison has been made with previous studies in this field. © 1979.