EAPSI: Converting Ultraviolet Light to Chemical Energy in Small Organic Molecules on an Ultrafast Timescale

Safko Trevor, Washington DC

Investigators

Abstract

Proton and electron transfers are the simplest of chemical reactions yet much about these fundamental processes still remains a mystery. One of the greatest difficulties in observing these events is the fast timescale on which they occur. A complex series of reactions can occur in under one billionth of a second. Recent advances in optics and engineering have given scientists the ability to observe previously invisible processes. Professor Gaolin Liang at the University of Science and Technology of China (USTC) has studied these 'simple' reactions with resolution of up to 0.1 trillionth of a second (100 femtoseconds). This type of equipment is revolutionizing our understanding of elementary reactions. This award supports a summer research collaboration in the Liang lab. The unique compounds to be investigated at USTC convert ultraviolet light into chemical energy. Monitoring this phenomena on a femtosecond timescale will inform our understanding of energy transfer mechanisms. Potential applications of this research include the design of more efficient solar cells, sensitive chemical detectors, and better energy storage. The compounds to be brought to USTC for this investigation participate in a proton-coupled charge-transfer (PCCT) reaction. The rapid, adiabatic transfer of a proton to the surrounding media is facilitated by a partial charge-transfer reaction. This PCCT reaction leads to the formation of an intramolecular charge-transfer complex (exciplex) which is readily observed by fluorescence spectroscopy. In order to gather thermodynamic and kinetic information about this rare phenomenon, transient absorption experiments will be completed at USTC. This is the first exciplex mediated proton-transfer event. It is imperative that the dynamics and extent of this process are better understood to broaden the current understanding of energy transfer mechanisms. This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the Ministry of Science and Technology of China.