Fleming and his research group were one of the key developers of 2D electronic spectroscopy (2D-ES), which enables scientists to follow the flow of light-induced excitation energy through molecular systems with femtosecond temporal resolution. Since its introduction in 2007, 2D-ES has become an essential tool for investigating the electronic relaxation and energy transfer dynamics of molecules, molecular systems and nanomaterials following photoexcitation. 2D infrared spectroscopy is the go-to tool for studying nuclear vibrational couplings and ground-state structures of chemical and complex biological systems.
"Combining these two techniques into 2D-EV tells us how photoexcitation affects the coupling of electronic and vibrational degrees of freedom," says Oliver. "This coupling is essential to understanding how all molecules, molecular systems and nanomaterials function."
In 2D-EV, a sample is sequentially flashed with three femtosecond pulses of laser light. The first two pulses are visible light that create excited electronic states in the sample. The third pulse is mid-infrared light that probes the vibrational quantum state of the excited system. This unique combination of visible excitation and mid-infrared probe pulses enables researchers to correlate the initial electronic absorption of light with the subsequent evolution of nuclear vibrations.
"2D-EV's ability to correlate the initial excitation of the electronicvibrational manifold with the subsequent evolution of high-frequency vibrational modes, which until now have not been explored, opens many potential avenues of fruitful study, especially in systems where electronicvibrational coupling is important to t
|Contact: Lynn Yarris|
DOE/Lawrence Berkeley National Laboratory