Soft X-ray Photoelectron Spectroscopy (XPS) and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy have been used to probe the electronic and adsorption properties of two cyclic dipeptides, i.e. cyclo(glycyl-histidyl) and cyclo(phenylalanyl-prolyl), on Au(111) and Cu(110) surfaces. The core level spectra show chemical shifts which indicate weak chemisorption on Au(111), and stronge...

The chemisorption of pyrimidine and s-triazine, two aromatic molecules with N atoms in the aromatic ring, is studied by first principles calculations to examine not only the chemisorption energy, but also the reaction barriers and the cooperative effects. Among the reaction paths at low coverage, the formation of a cross-bridge structure with two N-Si dative bonds is almost barrierless and shou...

Using first-principles calculations, we investigate the chemisorption of H, N, and P atoms on a graphene substrate with or without Stone–Thrower–Wales (STW) defects. Energetically, all three atoms are preferred to adsorb onto the defect sites by an energy difference of 0.683–2.143 eV. In both the intrinsic and defected graphene, H atom adsorbs on top of a C atom, while N and P atoms adsorb at t...

The adsorption of common gas molecules (N2, CO, CO2, H2O, NH3, NO, NO2, and O2) on germanene is studied with density functional theory. The results show that N2, CO, CO2, and H2O are physisorbed on germanene via van der Waals interactions, while NH3, NO, NO2, and O2 are chemisorbed on germanene via strong covalent (Ge-N or Ge-O) bonds. The chemisorption of gas molecules on germanene opens a ban...

The gas-surface reaction dynamics of NO impinging on an iron(II) phthalocyanine (FePc) monolayer were investigated using King and Wells sticking measurements. The initial sticking probability was measured as a function of both incident molecular beam energy (0.09-0.4 eV) and surface temperature (100-300 K). NO adsorption onto FePc saturates at 3% of a monolayer for all incident beam energies an...

The role of FTIR speetroscopy in catalytic studies is briefly discussed and some typical examples are shown. IR spectra of weakly bound hydrogen on PtjSi02 reveal surface heterogeneity; The hydrogen concentration on the surface is described by a Temkin isotherm. Adsorption of unsaturated C6 ring compounds on hydrogen poor PtjSi02 is essentially a self'-hydrogenation process resulting in the for...

The characterization and applications of topological insulators depend critically on their protected surface states, which, however, can be obscured by the presence of trivial dangling bond states. Our first-principle calculations show that this is the case for the pristine (111) surface of SnTe. Yet, the predicted surface states unfold when the dangling bond states are passivated in proper che...

A structural model for intermediate sized silicon clusters is proposed that is able to generate unique structures without any dangling bonds. This structural model consists of bulk-like core of five atoms surrounded by fullerene-like surface. Reconstruction of the ideal fullerene geometry results in the formation of crown atoms surrounded by π-bonded dimer pairs. This model yields unique struct...

The accuracy and efficiency of ab initio density functional theory calculations depend critically on the choice of pseudopotential. In this study, the merits of using large-core pseudopotentials for the dissociative chemisorption of oxygen on rhodium are discussed. The results show that these efficient pseudopotentials yield adsorption energies and bond distances of the oxygen atom to rhodium t...

Dissociative chemisorption is the initial and often rate-limiting step in many heterogeneous processes. As a result, an in-depth understanding of the reaction dynamics of such processes is of great importance for the establishment of a predictive model of heterogeneous catalysis. Overwhelming experimental evidence has suggested that these processes have a non-statistical nature and excitations ...