A systematic theoretical study using the density functional theory is performed to provide molecular-level understanding on the desorption of carbon monoxide from surface oxygen complexes that are formed in the gasification and combustion of coal. Particularly, a CO molecule release from carbonyl oxygen complexes in the presence of different oxygen environments was analyzed. Molecular carbonyl ...

We present Temperature Programmed Desorption (TPD) experiments of CO and N 2 ices in pure, layered and mixed morphologies at various ice " thicknesses " and abundance ratios as well as simultaneously taken Reflection Absorptio and to derive the kinetics for desorption, mixing and segregation. Forn Infrared Spectra (RAIRS) of CO. A kinetic model has been developed to constrain the binding energi...

Column experiments were conducted to investigate U(VI) desorption and sorption kinetics in a sand-textured, U(VI)-contaminated (22.7 micromol kg(-1)) capillary fringe sediment from the U.S. Department of Energy (DOE) Hanford site. Saturated column experiments were performed under mildly alkaline conditions representative of the Hanford site where uranyl-carbonate and calcium-uranyl-carbonate co...

The kinetics of thermal desorption from an excimer-laser-melted surface, on which diffusion into the bulk competes with desorption, is numerically evaluated and compared with a variety of experimental data for the case of Cl on Si: Auger electron spectroscopy, time-of-flight mass spectrometry, secondary-ion-mass spectrometry, and transient reflectivity. The model calculations involve nonequilib...

The desorption of atoms and molecules is one of the most fundamental of all surface processes. A distinction is usually made between ‘‘thermal’’ desorption and desorption induced by energetic sources of excitation, such as incident photons or electrons, that induce electronic transitions. The paper by Trenhaile and co-workers in this issue shows the surprising result that the ‘‘thermal’’ desorp...

Dredged sediment from Milwaukee Harbor showed two primary classes of particles in the <2 mm size range: a lighter-density coal- and wood-derived fraction with 62% of total PAHs and a heavier-density sand, silt, and clay fraction containing the remaining 38% of the PAHs. Room-temperature PAH desorption kinetic studies on separated sediment fractions revealed slow desorption rates for the coal-de...

Intermittent temperature-programmed desorption of ammonia was used to study the strength and population of surface acid sites of tungsten oxide supported on activated carbon pretreated at 350 and 700 degrees C. Catalysts pretreated at 350 degrees C showed two types of surface acid sites and desorption occurred with free readsorption until a temperature of around 300 degrees C was reached. Pretr...

The formal solution to the diffusion equation for transient adsorption in a semiinfinite medium with a strongly concentration dependent diffusivity, originally derived by Fujita ( 3 , has been extended to desorption. Profiles for adsorption and desorption are compared and simplified asymptotic expressions which are useful when the diffusivity ratio is large are derived. The effect of a strongly...

Femtosecond laser excitation and density functional theory reveal site and vibrational state specificity in neutral atomic hydrogen desorption from graphite induced by multiple electronic transitions. Multimodal velocity distributions witness the participation of ortho and para pair states of chemisorbed hydrogen in the desorption process. Very slow velocities of 700 and 400  ms^{-1} for H and ...

We measured polar angle (theta)-resolved time-of-flight spectra of D2 molecules desorbing from the Si(100)-(3x1) dideuteride surface. The desorbing D2 molecules exhibit a considerable translational heating with mean desorption kinetic energies of approximately 0.25 eV, which is mostly independent of the desorption angles for 0 degrees<or=theta<or=30 degrees. The observed desorption dynamics of ...