Environmental symmetry, influence

Symmetry breaking associated with chiral phenomena is a theme that recurs across the sciences—from the intricacies of the electroweak interaction and nuclear decay [1-3] to the environmentally influenced dimorphic chiral structures of microscopic planktonic foraminifera [4, 5], and the genetically controlled preferential coiling direction seen in the shells of snail populations [6, 7]. 

The possible explanation [233] for the environmental sensitivity of the transitions (nonhypersensitive) may be due to an increase in 7) parameters which results in lowering of the excited states of the ions since the surrounding crystal field is influenced by the symmetric part of the crystal field. The observed changes in 7 and the small nephelauxetic effect show that the nonsymmetric part of the crystal field affects 7 values. The modifier ions distort the oxygen bonded to the lanthanide and thus lowers the site symmetry and increases the f-f transition probability. 

The influence of environmental perturbations on the degree of allowedness of the symmetry-forbidden 0-0 band has been... 

It may be easily shown that all previously listed mechanisms are nonoperating in the case of a statistical-limit molecule. Its decay may be influenced by environmental effects only via their influence on intramolecular parameters (symmetry lowering, enhancement of the spin-orbit coupling by an external heavy-atom effect, etc.). 

---