The anomalous temperature dependence of the absorption spectrum and photochemical isomerization efficiency of 11-cis retinal is analyzed in terms of an equilibrium mixture of distorted 12-s-cis and distorted 12-s-trans conformers with the latter increasingly populated at lower temperature and/or greater solvent polarity. Inclusion of all possible singly and doubly excited configurations in the PFP formalism predicts a conformationally variant level ordering in that all 12-s-cis conformations have a lowest excited "1Bu"-like singlet state whereas the majority of the 12-s-trans conformations have a lowest excited "1Ag"-like singlet state.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry