First principles based theory complemented with electrospray ionization mass spectrometry to address environmental abiotic and biotic reactions

Abstract

We will summarize recent advances in First-principles based methods for predicting interfacial entropy and free energy with applications to reactions at surfaces of water contg. various electrolytes. At Caltech, we have recently adapted an electrospray ionization mass spectrometer to selectively probe physicochem. phenomena on liq. surfaces. Thus, together with theory and expts. we have demonstrated that (1) anions present at air-water interface can electrostatically preorganize surrounding water mols. to facilitate proton transfer events, (2) the neg. charge of the air-water interface is due to the presence of excess OH- at the aerial interface with a point-of-zero-charge at pH ∼ 3, and (3) rate enhancements obsd. in the proton catalyzed reactions at fluctuating aq. interfaces is due to inadequate hydration of hydronium, H_3O+. These findings should further our understanding of atm. chem., colloidal science, 'on-water' and enzymic catalysis and proton transfer reactions along and across membranes, including fuel cells and cellular processes.