Model molecular adsorption, hydrogen

In this chapter, recent results are discussed In which the adsorption of nitric oxide and its Interaction with co-adsorbed carbon monoxide, hydrogen, and Its own dissociation products on the hexagonally close-packed (001) surface of Ru have been characterized using EELS (13,14, 15). The data are interpreted In terms of a site-dependent model for adsorption of molecular NO at 150 K. Competition between co-adsorbed species can be observed directly, and this supports and clarifies the models of adsorption site geometries proposed for the individual adsorbates. Dissociation of one of the molecular states of NO occurs preferentially at temperatures above 150 K, with a coverage-dependent activation barrier. The data are discussed in terms of their relevance to heterogeneous catalytic reduction of NO, and in terms of their relationship to the metal-nitrosyl chemistry of metallic complexes. 

The basic experimental studies of the interactions between organophosphorus compounds and metal oxide surfaces have been carried out intensively during the last several years. Metal oxides, such as MgO, AI2O3, FeO, CaO, Ti02 a-Fe203, ZnO, and WO3, are currently under consideration as destructive adsorbents for the decontamination of chemical warfare agents [46, 47], For example, several studies have addressed adsorption of dimethyl methylphosphonate (DMMP) (a widely used model compound for the simulation of interactions of phosphate esters with a surface) on the surface of these metal oxides [48-60], In most of these works, the authors have observed that, at first, DMMP is adsorbed molecularly via hydrogen... 

Organic inhibitors in the nickel bath also influence the texture of nickel deposits. The inhibition effects are related to their molecular structure [6.69]. In the presence of brightners with unsaturated ethylenic or acetylenic compounds, the [110] texture is preferentially formed. With aryl-sulfonic compounds used as leveling agents, the [100] or [211] textures are favored. The modification of the crystal growth has been interpreted by an adsorption-hydrogenation-desorption model. The nature and the strength of a bond between a metallic surface and an adsorbed species depend on the... 

So far the 3D flat-surface model has been quite successful in providing qualitative and even some quantitative dynamics information for hydrogen dissociation on metals such as the role of hydrogen vibration and rotation in dissociative adsorption on Cu(lll) (104,114,117-119). However, the inherent limitation of the flat-surface model dictates that it cannot provide information on surface corrugation and its effect on molecular adsorption. One would like to investigate the effect of rotational orientation of diatomic molecules on chemisorption in the presence of surface corrugation. In order to obtain... 

Stimulated by these observations, Odelius et al. [73] performed molecular dynamic (MD) simulations of water adsorption at the surface of muscovite mica. They found that at monolayer coverage, water forms a fully connected two-dimensional hydrogen-bonded network in epitaxy with the mica lattice, which is stable at room temperature. A model of the calculated structure is shown in Figure 26. The icelike monolayer (actually a warped molecular bilayer) corresponds to what we have called phase-I. The model is in line with the observed hexagonal shape of the boundaries between phase-I and phase-II. Another result of the MD simulations is that no free OH bonds stick out of the surface and that on average the dipole moment of the water molecules points downward toward the surface, giving a ferroelectric character to the water bilayer. 

In order to explain the catalytic activity of PANI, we have modeled the electronic structure of doped molecular PANI clusters and its adsorption complexes with oxygen and hydrogen. The geometric and electronic... 

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