ABSTRACT
A great number of chemical reactions occur in liquids and at interfaces. In describing the chemical dynamics in the above environments, one usually simplifies a system to portray only the reactive site and its immediate surroundings. The thought of a localized active site forms the basis for conceptualizing the chemical reactivity. Our understanding of chemical reactivity comes from knowledge of elementary steps from such a localized viewpoint. The elementary steps include changes in the electron distribution, molecular structure, and translocation of chemical moieties. However, these processes are inevitably modulated by the surrounding media, the time scales of which are typically on the order of picoseconds or less. Therefore, a critical test of our fundamental understanding of chemical reactivity requires experimental techniques that allow resolution of those ultrafast events. Femtosecond infrared (fs-IR) offers such an opportunity.
