Surface Assisted Transient Displacement Charge Technique. I. Photoinduced Charge Transfer in Self-assembled Monolayers

摘要

Surface assisted photoinduced transient displacement charge (SPTDC) technique was developed in order to study light induced charge transfer in surface bound molecules and applied to investigation of self-assembled monolayers of 7-diethylaminocoumarin and 2,4-dinitrophenylamine. The dipole moment change measured by SPTDC correlates reasonably well with that measured in solution by standard PTDC technique and with semiempirical calculations. Shortening of the excited state lifetime of surface immobilized coumarin due to stimulated emission was observed in both fluorescence and dipole measurements. The dipole signal decline in low polarity solvents indicates the importance of dipole-dipole interaction that causes reorientation of molecules upon photoexcitation.