Electric field effects on photoisomerization process of diphenylpolyenes doped in a polymer film as revealed by a field-induced change in fluorescence spectrum

Effect of the external electric field on photoisomerization dynamics of diphenylpolyenes doped in a PMMA polymer film has been examined by using electromodulation spectroscopy in absorption and emission. A significant decrease in fluorescence intensity is found in the presence of an external electric field, suggesting that trans-to-cis isomerization of diphenylpolyenes is accelerated by an electric field in the S1 state. The present results support the zwitter ionic model for the photoisomerization pathway of diphenylpolyenes. Photoisomerization of diphenylpolyenes is also shown to occur in a PMMA film.