New insight brought by density functional theory on the chemical state of alaninol on Cu(100): Energetics and interpretation of x-ray photoelectron spectroscopy data

摘要

In recent years, an increasing interest has been focused on the adsorption of molecules on surfaces due to the importance of technologies based on the interaction of organic systems with metals and oxides for biosensors, catalysis, and molecularly imprinted polymer technology. A particularly attractive area is the study of chiral surfaces, as these can act as heterogeneous catalysts and sensors in the stereochemical industrial processes. This work reports on an ab initio simulation of chemisorption of the D-alaninol on Cu (100). This system has been investigated systematically by using the Vienna ab initio simulation Package (VASP) which performs density functional theory (DFT) calculations in periodic boundary conditions. Molecular dynamics at 300 K is performed to explore all the possible geometries, finally, optimized at 0 K to obtain the adsorption modes. C 1s, O 1s, and N 1s, core level shift (CLS) calculations of those adsorption modes have been evaluated and compared with x-ray photoelectron spectroscopy experimental data. Energetic and CLS indicate that both chemical functions, the NH2 and the dehydrogenated hydroxyl, are involved in the bonding to the surface at low coverage. Atomic hydrogen coadsorbs in a fourfold hollow site. An atomistic thermodynamics approach suggests that at room temperature under UHV conditions, coadsorbed hydrogen has recombined as H-2 and desorbed from the surface.