Spectroscopy of organics at water-air interfaces relevant to environmental systems

Inspired by atmospheric measurements, which have established that atmospheric chemistry occurs in many phases and at interfaces, my group explored the unique reaction environments presented by planetary atmospheres using surface reflection spectroscopies. In this presentation, IRRAS and UVRES methods are described long with results for chemical and photochemical experiments at the water surface. The special morphological and chemical properties of organic films on aqueous solutions will be discussed with reference to atmospheric aerosols, sea surface microlayers, cloud and fog droplets. The surface of water on aqueous drops and at the sea surface provides a special and unique reaction environment with qualitatively different thermodynamic and kinetic properties from bulk aqueous solutions. Examples will be presented of surface reflection studies to follow chemistry initiated at the water surface leading to increase in the chemical complexity of the system. Solar radiation is the largest source of energy on both the contemporary and early Earth. Multiphase photochemical mechanisms will be discussed by which -keto acids react in aqueous environments to form organic radicals, which then recombine to form larger, more complex lipids. The relevance of this chemistry to reactions in the contemporary atmosphere as well as chemistry that may have occurred prebiotically, in the absence of enzymes on ancient Earth, will be discussed.