Combined Application of Picosecond Transient Absorption and Emission Measurements in Studies of Radical-Ion Pair Dynamics

Abstract— Much of the emphasis in the development of methods for time-resolved measurements is on increasing experimental time resolution. Equally important, however, is the establishment of methods to apply existing techniques to problems of increasing complexity. Here we describe the application of a combination of picosecond absorption and emission measurements to solve a complex kinetic problem in organic photophysics, namely, the dynamics of interconverting radical-ion pairs. Although fairly routine, the emission measurements require higher time resolution and the absorption measurements require higher signal-to-noise ratios than are often achieved. In the first part of this paper we describe the ways in which these experimental requirements have been met. Next, the radical-ion pair kinetic problem and its solution are described. Finally, we discuss some future directions for the techniques as they relate to studies of radical-ion pair dynamics.