PHOTOINDUCED ELECTRON-TRANSFER ON THE SURFACES OF MICELLES

Photoinduced electron transfer between N,N-dimethylaniline (DMA) and o ctadecylrhodamine B (ODRB) is studied on the surfaces of three alkyltr imethylammonium bromide micelles: dodecyl- (DTAB), tetradecyl- (TTAB), and hexadecyltrimethylammonium bromide (CTAB). The DMA and ODRB molec ules are localized at the micelle surface. Time-resolved fluorescence and fluorescence yield data are presented and analyzed with the theore tical methods of ref 1. Lateral diffusion of the molecules over the mi celle surfaces is included. Although the three micelles are structural ly similar, pronounced differences in the electron-transfer kinetics a re observed, with the overall amount of electron transfer increasing w ith alkyl chain length for the same DMA surface packing fraction. This result is attributed to differences in the solvent reorganization ene rgy, possibly due to varying extents of water penetration into the hea dgroup regions of the three micelles. As the surfactant chain length i ncreases, the solvent reorganization energy is reduced, resulting in f aster electron transfer.