Advances in the transient dc photocurrent technique for excited state dipole moment measurements

Recent advances in the transient de photocurrent technique for measuring excited state dipole moments, developed in our group, are discussed. A variety of approaches with detailed analyses of their advantages and disadvantages including eel design, circuit construction tricks, the data acquisition procedure, calibration, and the theoretical treatment of different conditions, are presented. Sensitivity, time resolution limitations, and newly developed features, such as the signal's dependence on light polarization as well as charge separation at interfaces are outlined. Dipole moments of a :few molecules (diphenylcyclopropenone, bianthryl, dimethylaminonitrostilbene, Coumarin 153, and fluoroprobe) suitable for calibration purpose are reported-some of them for the first time. (C) 1998 American Institute of Physics.