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Upper Jurassic marine deposits are either rarely preserved due to erosion or buried under younger sediments in the Bohemian Massif. However, fossil assemblages from a few successions exposed in northern Bohemia and Saxony and preserved in museum collections document the regional composition of macro-invertebrate assemblages and thus provide unique insights into broad-scale distribution and migration pathways of ammonites during the Late Jurassic. In this paper, we focus on the systematic revision of ammonites from the Upper Oxfordian and Lower Kimmeridgian deposits of northern Bohemia and Saxony. The ammonites belong to two families (Aulacostephanidae and Cardioceratidae) of high paleobiogeographic and stratigraphic significance. Six genera belong to the family Aulacostephanidae (Prorasenia, Rasenia, Eurasenia, Rasenioides, Aulacostephanus, Aulacostephanoides) and one genus belongs to the family Cardioceratidae (Amoeboceras). They show that the Upper Jurassic deposits of the northern Bohemian Massif belong to the Upper Oxfordian and Lower Kimmeridgian and paleobiogeographically correspond to the German-Polish ammonite branch with the geographical extent from the Polish Jura Chain to the Swabian and Franconian Alb. Therefore, the occurrences of ammonites described here imply that migration pathway connecting the Polish Jura Chain with habitats in southern Germany was located during the Late Oxfordian and Early Kimmeridgian in the Bohemian Massif.

Mixed-metal oxides play a very important role in many areas of chemistry, physics, materials science, and geochemistry. Recently, there has been a strong interest in understanding phenomena associated with the deposition of oxide nanoparticles on the surface of a second (host) oxide. Here, scanning tunneling microscopy, photoemission, and density-functional calculations are used to study the behavior of ceria nanoparticles deposited on a Ti[O.sub.2](110) surface. The titania substrate imposes nontypical coordination modes on the ceria nanoparticles. In the Ce[O.sub.x]/Ti[O.sub.2](110) systems, the Ce cations adopt an structural geometry and an oxidation state (+3) that are quite different from those seen in bulk ceria or for ceria nanoparticles deposited on metal substrates. The increase in the stability of the [Ce.sup.3+] oxidation state leads to an enhancement in the chemical and catalytic activity of the ceria nanoparticles. The codeposition of ceria and gold nanoparticles on a Ti[O.sub.2](110) substrate generates catalysts with an extremely high activity for the production of hydrogen through the water-gas shift reaction ([H.sub.2]O + CO [right arrow] [H.sub.2] + C[O.sub.2]) or for the oxidation of carbon monoxide (2CO + [O.sub.2] [right arrow] 2C[O.sub.2]). The enhanced stability of the [Ce.sup.3+] state is an example of structural promotion in catalysis described here on the atomic level. The exploration of mixed-metal oxides at the nanometer level may open avenues for optimizing catalysts through stabilization of unconventional surface structures with special chemical activity. heterogeneous catalysis | imaging | structural properties | surface reactivity

The formation of MoO3 and its spontaneous spread over an Au (111) surface is studied by X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). O2 and NO2 oxidations of Mo clusters deposited on Au (111) via Mo(CO)6 CVD are compared. The results indicate that the Mo clusters on Au are probably encapsulated by gold.

The growth of a submonolayer of metallic Mo on Au (11) by using scanning tunnel microscopy (STM) is studied. The results show the oxidation of Mo islands leading to their spreading proving that Mo clusters are either three-dimensional above or embedded in the surface of the gold substrate.

A systematic study of the interaction of sulfur with Au(III) and polycrystalline gold is carried out using synchrotron-based spectroscopy, thermal desorption mass spectroscopy (TDS), and first-principles DF calculations. The adsorption of S on fcc hollow sites of the gold substrate is energetically more favorable than adsorption on bridge or a-top sites, in the case of small sulfur coverages, whereas, the photoemission and DF results show a complex behavior for the sulphur/Au(111) interface as a function of coverage and temperature.

Research has been conducted on the interactions of gold with titania. The synchrotron-based high-resolution photoemission and density functional slab calculations used in examining these interactions and the chemistry of SO (sub)2 on Au/TiO (sub)2 (110) surfaces are discussed.

Research into the interaction of NO2 with a TiO2(110) single crystal and powders of titania is presented. It was found that the main product of the adsorption of NO2 on TiO2(110) is surface nitrate with a small quantity of chemisorbed NO2.

A study was conducted to analyze the trimerization of acetylene to benzene on a Cu(100) surface. The study was carried out in a stainless steel chamber supporting four-grid LEED apparatus, a quadrupole mass spectrometer and an Auger spectrometer. Results indicated that the mass 26 signal imitated the trimerization rate at high coverages. Findings also showed that increases in the reaction yield correlated with increases in the initial acetylene coverage.

The surface chemistry of SO2 on polycrystalline Sn, Pt(111) and a (square root of 3 x square root of 3)R30deg-Sn/Pt(111) surface alloy was studied through synchrotron-based high-resolution photoemission and ab initio self-consistent field computations. The Sn/Pt system shows how a redistribution of electrons that happens in bimetallic bonding can be helpful in the design of catalysts that have an unusually low reactivity toward SO2 and for controlling sulfur poisoning.

Synchrotron-based high-resolution photoemission was used to analyze adsorption and dissociation of H2S and S2 on a series of oxide and metal/oxide surfaces. H2S and S2 generally interact with the metal centers of oxides. At 300 K, H2S undergoes total decomposition. The rate of decomposition on Al2O3 is much lower than those observed on Cr3O4, Cr2O3, ZnO and Cu2O. For these systems, the smaller the band gap in the oxide, the bigger its reactivity toward S-containing molecules. The use of ab initio self-consistent-field calculations and a model that unifies perturbation theory with Huckel and tight-binding approach are discussed.

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Examines the interaction of sulfur with Pt(111) and Sn/Pt(111) surface alloy. Variation of the nature of bonding of sulfur; Decrease on the density of Pt due to sulfur; Reduction of the reactivity of Pt toward sulfur; Impact of electronic effects associated with bimetallic bonding on sulfur poisoning.

A combination of scanning tunneling microscopy and density-functional approaches is employed to explain the properties of the various gold, copper and platinum nanoparticles dispersed on the Ce[O.sub.x]/Ti[O.sub.2](110) surfaces. The various properties of the mixed-metal oxide observed at the nanometer level are also discussed.

CO adsorption on the Au(111) surface is increased by controlling the length of steps and the weakly adsorbed CO has induced irreversible morphological changes of the surface even at temperature below 180 K and very low CO pressures. The studies have pointed toward the dynamic response of surfaces to even weakly adsorbing reactants during catalytic reactions.

A scanning tunneling microscopy (STM) study of the growth of Ru particles on a highly oriented pyrolytic graphite surface by chemical vapor deposition through a Ru3(CO)12 precursor, is presented. The possibility to form high density of atomic N on the surface may be the reason for the high activity of Ru/C catalysts in the ammonia synthesis.