Fig. 9.
The key normal modes of all-trans C18 (left) and central-cis C18 (right) responsible for the radiationless decay of the lowest-lying 21Ag- singlet state. The dimensionless coordinate shift (ΔQ, Eq. 7) and the electronic coupling term (H, Eq. 8) are listed along with the vibrational frequency (σ), in wavenumbers.