When plasmas encounter surfaces, energetic ion bombardment can drive chemical reactions different from those occurring in thermal processes. We have discovered that tri-atomic molecules may dissociate in totally unpredictable ways, for example, water can be split directly into molecular hydrogen andatomic oxygen in single-collision events. More surprisingly, carbon dioxide—an exceptionally stable triatomic molecule—can be decomposed directly to molecular oxygen and carbon. Such momentumdriven reactivity may be important in astrophysical environments and could offer new ways to rid Earth’s atmosphere off of CO2 or produce breathable oxygen on Mars. The talk will introduce the relevance of such reactions and focus on providing experimental evidence and a theoretical framework of the violent intra-molecular changes, which facilitate the transformation or the linear CO2 molecule to a conformation that spontaneously dissociates into molecular oxygen. The dissociation behaviour will be contrasted with another unexpected reaction of CO2 (and H2O) on oxidized surfaces, namely the abstraction of atomic oxygen, which also produces O2 dynamically in comets. Such reactions may be taken advantage of in specially designed plasma reactors.
Konstantinos P. Giapis is a Professor of Chemical Engineering at the California Institute of Technology. He holds a Ph.D. degree in Chemical Engineering from the University of Minnesota. He was postdoctoral member of technical staff at Bell Laboratories, Murray Hill (NJ) before joining the California Institute of Technology in 1992. His current research interests include plasma chemistry, gas-surface dynamics, and fundamental aspects of nanoscience. The Rosetta mission has inspired him to move part of his research to Astrophysics, where he explores abiotic reaction pathways to produce small organic molecules relevant to the origin of life. He has received an NSF Career Award and a Dreyfus Teacher-Scholar Award.