A new method for measuring intramolecular charge transfer.

The direct measurement of intramolecular electron transfer through detection of the electromagnetic (EM) waveform that is emitted during this process is reviewed. The waveform is detected in the time-domain via free-space electro-optic sampling and then related to the dynamics of the charge transfer event. Electromagnetic generation from two systems, Betaine-30 in chloroform and DMANS in toluene, are studied to illustrate this technique. A finite-difference time-domain calculation with a time-dependent polarization is used to model the EM generation and propagation through the solution. This method is very general since the movement of charge itself generates the EM waveform, and is sensitive to charge transfer occurring on a 0.1-10 ps timescale. The potential for studying the primary steps of charge transfer in photosynthetic bacteria is also discussed.