Photoinduced chemical reactions happening at the air-water interface are as prevalent in the present-day atmosphere as in prebiotic earth. Research on these reactions is of great interest, as it holds insights for a wide range of fields, ranging from catalysis chemistry to atmospheric sciences. There is a remarkable difference between the reactions occurring at the air-water interface and their bulk counterparts. The reaction rate increases by six to seven orders of magnitude for some reactions, while other reactions at the interface produce products vastly different from their bulk counterparts. However, the reason for this stark difference in reaction behaviors at the interface is not yet understood. Using time-resolved resolved vibrational sum-frequency generation (TR-VSFG) spectroscopy, we are studying photoinduced reactions at the air-water interface. Photoinduced reactions are chosen because a tunable UV-Vis pump pulse can define time zero by photoexciting targeted molecules. A phase-sensitive VSFG probe can then be used to follow the ensuing structural, orientational, and dynamical changes to the reagent as well as to the hydrogen bonding network of water at the interface. Understanding changes to the water structure and dynamics at the interface is paramount to understanding the reaction acceleration.
