Paper SS-ThM11
Enantioselective Decomposition of L and D Tartaric Acid on Copper Surface Structure Spread Single Crystals

Thursday, October 31, 2013, 11:20 am, Room 202 A

The role of atomic surface structure in catalytic reactions requires a fundamental understanding to develop new catalysts. Surface Structure Spread Single Crystals (S⁴Cs) expose a continuous distribution of crystal planes across their surfaces. Each point on the S⁴Cs has a different local crystallographic orientation that can be determined from the shape of the S⁴Cs and the orientation of its bulk crystal lattice vectors. The majority of crystal planes on these S⁴Cs contains terraces, monatomic steps, and kinks and can be described as chiral with an R or an S orientation. When coupled with spatially resolved surface analysis techniques, S⁴Cs can be used to study the effects of surface chiralty on surface chemistry across a broad, continuous distribution of crystal planes. In this work, the enantioselectivity of the explosive decomposition of L and D tartaric acid was studied using Cu(100)±10°, Cu(110)±10°, and Cu(111)±10° S⁴Cs. We used Isothermal Temperature Programmed Desorption (TPD) in which each sample was held at a temperature >20 K below the temperature of peak decomposition observed in a standard (TPD) experiment until the decomposition reaction occurred. Spatially resolved X-ray Photoelectron Spectroscopy (XPS) was performed to determine which crystal planes on each S⁴C had undergone explosive decomposition after quenching the temperature of each sample at the decomposition peak during an isothermal TPD. It was found that D-tartaric acid decomposes before L-tartaric acid on R oriented surfaces and L-tartaric acid decomposes before D-tartaric acid on S oriented surfaces on all three Cu S⁴Cs.