Abstract
Deca-picosecond to nanosecond time-resolved, absorption spectroscopy applied to a set of cis-trans isomers of retinal, retinylideneacetaldehyde and β-carotene is summarized. No configurational changes have been detected in the singlet excited-state (S1) of either retinylideneacetaldehyde or β-carotene. Configurational changes (isomerization) have been detected in the triplet excited-state (T1) of retinal, retinylidene acetaldehyde and β-carotene. The rate of triplet isomerization was dependent on the starting ground-state configuration; it is the highest for the central-bent, unmethylated-cis configuration, and it is the lowest for the all-trans configuration.
