Hyperfine-Induced Ungerade-Gerade Symmetry Breaking in a Homonuclear Diatomic Molecule near a Dissociation Limit: ^{127}I_{2} at the ^{2}P_{3/2}-^{2}P_{1/2} Limit
Résumé
A symmetry breaking of the ungerade-gerade character through hyperfine perturbation has been directly observed for the first time in a homonuclear diatomic molecule (127I2). An important consequence of this symmetry breaking is the mixing of ortho and para modifications. Evidenced by anomalies in the observed hfs of high-lying rovibrational levels in the B 0u+ state and extra lines, it is due to a hyperfine perturbation of this state by a 1g state sharing the same dissociation limit. Such a situation should be met in other molecules.