The projects in my research group are directed at the characterization of complex chemical systems (nanoscale materials, inorganic coordination complexes, and interfacial environments) using femtosecond laser spectroscopy. We use a variety of ultrafast spectroscopic techniques, including time-resolved absorption, emission, and polarization anisotropy methods, as well as non-linear spectroscopies, to study the photoinduced dynamics on time scales ranging from femtoseconds to nanoseconds. In all of these methods, a dynamical process (e.g. electron transfer) is initiated by the absorption of a photon from femtosecond laser pulse, termed the pump pulse.

After a well-defined period of time, a second laser pulse, termed the probe pulse, passes through the sample. The evolution of the photoexcited system is then followed by measuring the intensity change of the second laser pulse as a function of time between the pump and probe pulses. In this manner we can observe the flow of charge and energy between different chemical constituents, vibrational cooling of photoexcited chromophores, and structural reorganization of the environment in response to photoinduced changes in the solute charge distribution. We augment our ultrafast spectroscopic experiments with computer modeling (e.g. Monte Carlo and Molecular Dynamics simulations), steady state absorption and emission spectroscopy, electrochemistry, light scattering, electron microscopy, and NMR to gain a complete picture of the relationship between the structure and function of a material at the molecular level.