The fluorescence lifetimes of methyl cinnamate and methyl indenoate have been investigated by means of picosecond laser spectroscopy. Values of <3 ps and 15 ± 2 ps for these esters are significantly shorter than those previously reported for ethyl cinnamate. The short lifetimes are tentatively attributed to the competition between fluorescence from the originally populated π,π* singlet state and its internal conversion to a lowest n,π* singlet state. The efficiency of isomerization is independent of solvent, but dependent upon temperature and excitation wavelength. Comparison of the quantum yields for direct and triplet-sensitized dimerization indicates that intersystem crossing is highly inefficient. Thus the isomerization which occurs upon direct irradiation occurs predominantly from the singlet manifold.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Photochemistry and Photobiology, A: Chemistry|
|State||Published - May 1989|
ASJC Scopus subject areas
- Chemical Engineering(all)
- Physics and Astronomy(all)