Paper IS+AS+SS-TuM9
Surface Chemistry of Amino Acids at Near Ambient Pressure of Water Vapor
Tuesday, November 1, 2011, 10:40 am, Room 106
| Session: |
In Situ Studies of Organic and Soft Materials and Liquid-Solid Interfaces |
| Presenter: |
Andrey Shavorskiy, Lawrence Berkeley National Laboratory |
| Authors: |
A. Shavorskiy, Lawrence Berkeley National Laboratory
T. Eralp, The University of Reading, UK
F. Aksoy, Nigde University, Turkey
M.E. Grass, Lawrence Berkeley National Laboratory
Z. Liu, Lawrence Berkeley National Laboratory
H. Bluhm, Lawrence Berkeley National Laboratory
G. Held, The University of Reading, UK
|
| Correspondent: |
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The co-adsorption of water with organic molecules under near-ambient pressure and temperature conditions opens up new reaction pathways on model catalyst surfaces that are not accessible in conventional ultra-high vacuum surface-science experiments. The surface chemistry of glycine and alanine at the water-exposed Cu{110} and Pt{111} interface was studied both in situ and in UHV using ambient-pressure photoemission and X-ray absorption spectroscopy techniques [1,2]. At water pressures above 10-5 Torr a significant pressure-dependent decrease in the temperature for dissociative desorption was observed for both amino acids on Cu{110}[3]. On Pt{111}, on the other hand, desorption temperature does not depend significantly on the presence of water vapor. The most likely reaction mechanism of decomposition involves dehydrogenation induced by O and/or OH surface species resulting from the dissociative adsorption of water on Cu{110}, but not on Pt{111}.
The linear relationship between the inverse decomposition temperature on Cu{110} and the logarithm of water pressure enables determination of the activation energy for the surface reaction, between 213 and 232 kJ/mol, and a prediction of the decomposition temperature at the solid-liquid interface by extrapolating towards the equilibrium vapour pressure. Such experiments near the equilibrium vapour pressure provide important information about elementary surface processes at the solid-liquid interface, which can neither be retrieved under ultra-high vacuum conditions nor from interfaces immersed in a solution.
[1] H. Bluhm, et al. J. El. Spec. Rel. Phenomena 150 (2006) 86.
[2] G. Jones, L. B. Jones, F. Thibault–Starzyk, E.A. Seddon, R. Raval, S. Jenkins, G. Held, Surf. Sci. 600 (2006) 1924.
[3] A. Shavorskiy, F. Aksoy, M.E. Grass, Z. Liu, H. Bluhm, G. Held, J. Am. Chem. Soc, 133 (2011) 17