A Step toward the Wet Surface Chemistry of Glycine and Alanine on Cu{110}: Destabilization and Decomposition in the Presence of Near-Ambient Water Vapor

Abstract

The coadsorption 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 ultrahigh-vacuum surface-science experiments. The surface chemistry of glycine and alanine at the water-exposed Cu{110} interface was studied in situ using ambient-pressure photoemission and X-ray absorption spectroscopy techniques. At water pressures above 10(-5) Torr a significant pressure-dependent decrease in the temperature for dissociative desorption was observed for both amino acids, accompanied by the appearance of a new CN intermediate, which is not observed for lower pressures. The most likely reaction mechanisms involve dehydrogenation induced by O and/or OH surface species resulting from the dissociative adsorption of water. The linear relationship between the inverse decomposition temperature 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 toward the equilibrium vapor pressure. Such experiments near the equilibrium vapor pressure provide important information about elementary surface processes at the solid-liquid interface, which can be retrieved neither under ultrahigh vacuum conditions nor from interfaces immersed in a solution.

UHV and Ambient Pressure XPS: Potentials for Mg, MgO, and Mg(OH)2 Surface Analysis

“…For example, the interaction of mineral surfaces, 44 semiconductors, 45 ice, 46 aerosol particles, 47 and amino acids 48 with water has been studied as well as the chemical speciation at the liquid/vapor interface in deliquesced salts 49 and liquid jets. 50 Standing wave spectroscopy has been used to obtain sub-nanometer resolution at the liquid/solid interface in Ni corrosion 51 and ion speciation at the hematite/water interface.…”

Ambient‐Pressure X‐Ray Photoelectron Spectroscopy

“…APXPS has shown its ability to track changes in the chemical state of simple chiral organic compounds, such as amino acids, adsorbed on metals in the presence of water vapor [40,41]. Figure 14.10 shows N 1s temperature-programmed (TP) XPS spectra of glycine on Pt(1 1 1) (a) and Cu(1 1 0) (b) taken in vacuum.…”

Energy landscapes and dynamics of glycine on Cu(110)

“…6,7 Adsorption of amino acids on copper surfaces has been intensively studied over the last two decades, both experimentally and theoretically. Copper surfaces are often chosen as substrate because amino acids are stable onto copper up to about 500 K, 8 while transition metal substrates such as nickel are known to catalyse dissociation even at moderate temperature. 9 Glycine adsorbed on Cu(110) is one of the amino acid/ metal systems that has been more thoroughly investigated by diffraction techniques (LEED 10,11 , PhD 12 ), microscopy (STM 11,13 ), IR and X-ray spectroscopy (RAIRS 11,14 , NEXAFS 10 , XPS 8,10 ) as well as density functional theory (DFT).…”

“…Copper surfaces are often chosen as substrate because amino acids are stable onto copper up to about 500 K, 8 while transition metal substrates such as nickel are known to catalyse dissociation even at moderate temperature. 9 Glycine adsorbed on Cu(110) is one of the amino acid/ metal systems that has been more thoroughly investigated by diffraction techniques (LEED 10,11 , PhD 12 ), microscopy (STM 11,13 ), IR and X-ray spectroscopy (RAIRS 11,14 , NEXAFS 10 , XPS 8,10 ) as well as density functional theory (DFT). [15][16][17] More recently, other low-index copper surfaces such as Cu(311) have been considered for studying glycine selfassembly without footprint chirality.…”

“…Although glycine is not intrinsically chiral, when adsorbed on the Cu(110) surface it produces the same chiral footprint typical of alanine 11,20,21 and proline 2, 22-24 on this surface, so glycine can be used as a model to understand the assembly of more complex amino acids on Cu(110). 2,8,25 Even though the bonding, structure and long range arrangement of glycine on Cu(110) have been investigated by several groups using a wide range of experimental 8,13,14,26 and computational tools 15,17,27,28 , the energy barriers between adsorbed conformers and the dynamics of glycine surface diffusion are still largely unresolved. In this work we have investigated, using DFT calculations, the energy landscapes of glycine conformers with identical footprint chirality and possible reaction pathways that convert the footprint chirality.…”