Coverage-dependent sticking probabilities and second-order rate constants for recombinative desorption of hydrogen from Rh( 111 ) have been measured using molecular beam relaxation spectroscopy (MBRS) and time-resolved specular helium scattering. The sticking probability follows second-order Langmuir coverage dependence, with So equal to 0.01 ___ 0.005. Under isothermal and nearly isosteric con...

The water relations play a fundamental role in seed comprehension of biology. In order to describe the process of drying and the effect on water activity, which controls biological change in storage, a sound knowledge of the relationship between equilibrium moisture content (EMC) and water activity/equilibrium relative humidity (ERH) is essential. The relationship between the total moisture con...

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...