Ultrafast studies on electron transfer in the betaines: evidence for local heating

摘要

We have made ultrafast time resolved pump probe measurements on the intramolecular electron transfer (ET) of the betaines, specifically betaine30 and penta-t-butyl betaine. The data have been analyzed to determine the ET rate in a range of solvent environments, at various temperatures and at a variety of pump and probe wavelengths. In all cases, the observed ET rate is fast, often faster than predicted by common ET theories. As a result, we have extended some common theories to successfully predict the measured ET rates. In addition to the ET dynamics, the data also display evidence for local heat deposition in the immediate vicinity of the betaine molecule which our extended model qualitatively predicts.