A rule which describes whether particular quantum transitions in an atom or molecule are allowed or forbidden.
- ‘There are simple selection rules that usually work in spectroscopy, corresponding to the known properties of atoms.’
- ‘Because the selection rules for one- and two-photon transitions differ, it is possible that 2PE can occur at energies where no corresponding one-photon absorption exists.’
- ‘This issue is related to the inhibition of carrier relaxation due to the selection rule of interaction between electrons and phonons in discrete energy level systems.’
We take a look at several popular, though confusing, punctuation marks.