Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

The surface science of titanium dioxide

In 1978 it was discovered, largely through the work of Fleischmann, Van Duyne, Creighton, and their coworkers that molecules adsorbed on specially prepared silver surfaces produce a Raman spectrum that is at times a millionfold more intense than expected. This effect was dubbed surface-enhanced Raman scattering (SERS). Since then the effect has been demonstrated with many molecules and with a number of metals, including Cu, Ag, Au, Li, Na, K, In, Pt, and Rh. In addition, related phenomena such as surface-enhanced second-harmonic generation, four-wave mixing, absorption, and fluorescence have been observed. Although not all fine points of the enhancement mechanism have been clarified, the majority view is that the largest contributor to the intensity amplification results from the electric field enhancement that occurs in the vicinity of small, interacting metal particles that are illuminated with light resonant or near resonant with the localized surface-plasmon frequency of the metal structure. Small in this context is gauged in relation to the wavelength of light. The special preparations required to produce the effect, which include among other techniques electrochemical oxidation-reduction cycling, deposition of metal on very cold substrates, and the generation of metal-island films and colloids, is now understood to be necessary as a means of producing surfaces with appropriate electromagnetic resonances that may couple to electromagnetic fields either by generating rough films (as in the case of the former two examples) or by placing small metal particles in close proximity to one another (as in the case of the latter two). For molecules chemisorbed on SERS-active surface there exists a "chemical enhancement" in addition to the electromagnetic effect. Although difficult to measure accurately, the magnitude of this effect rarely exceeds a factor of 10 and is best thought to arise from the modification of the Raman polarizability tensor of the adsorbate resulting from the formation of a complex between the adsorbate and the metal. Rather than an enhancement mechanism, the chemical effect is more logically to be regarded as a change in the nature and identity of the adsorbate.

Surface-enhanced spectroscopy

Analysis of XPS spectra of Fe2+ and Fe3+ ions in oxide materials

Molecular self-assembly is the spontaneous association of molecules under equilibrium conditions into stable, structurally well-defined aggregates joined by noncovalent bonds. Molecular self-assembly is ubiquitous in biological systems and underlies the formation of a wide variety of complex biological structures. Understanding self-assembly and the associated noncovalent interactions that connect complementary interacting molecular surfaces in biological aggregates is a central concern in structural biochemistry. Self-assembly is also emerging as a new strategy in chemical synthesis, with the potential of generating nonbiological structures with dimensions of 1 to 10(2) nanometers (with molecular weights of 10(4) to 10(10) daltons). Structures in the upper part of this range of sizes are presently inaccessible through chemical synthesis, and the ability to prepare them would open a route to structures comparable in size (and perhaps complementary in function) to those that can be prepared by microlithography and other techniques of microfabrication.

Molecular self-assembly and nanochemistry: A chemical strategy for the synthesis of nanostructures

The electronic spectra of CO chemisorbed on transition metals and copper as obtained with photoelectron spectroscopies, surface Penning spectroscopy, inverse photoemission spectroscopy, and x-ray absorption spectroscopy are discussed in regard to inherent features pointing to the existence of a CO 2${\ensuremath{\pi}}^{\mathrm{*}}$--derived resonance in these adsorption systems. Since the various spectroscopies probe the CO-metal systems predominantly in the excited final state, the spectra of one and the same line, however, are also affected by differences in the dynamic relaxation processes and nonequilibrium final-state charge configurations which are specific to each particular experimental method. In order to arrive at a unified interpretation of some seemingly controversial features in the electronic spectra of chemisorbed CO, we have invoked the notion of the CO 2${\ensuremath{\pi}}^{\mathrm{*}}$--derived resonance. Our model includes both initial-state chemical (i.e., backdonation-induced bonding) effects and final-state dynamical screening (relaxation) effects. Assuming a very small fractional occupation of the CO 2${\ensuremath{\pi}}^{\mathrm{*}}$ resonance in the case of weak chemisorption systems (e.g., CO/Cu), and notably larger occupation in the case of strong chemisorption (e.g., CO/Ni), it is possible to give a unified interpretation of the experimental features such as the threshold energies, level shifts, line shapes, etc., observed with CO adsorbed on transition metals and copper. The great success of the concept of a resonance in interpreting these experimental spectral features as obtained with the various spectro- scopies, provides, in turn, strong support for the actual existence of a CO 2${\ensuremath{\pi}}^{\mathrm{*}}$-- derived resonance in these adsorption systems.

2 pi resonance features in the electronic spectra of chemisorbed CO.

An X-ray photoelectron spectroscopy study of the chemical changes in oxide and hydroxide surfaces induced by Ar+ ion bombardment

This Letter analyzes peaks in ultraviolet photoemission spectra due to the $5{p}_{\frac{3}{2}}$ and $5{p}_{\frac{1}{2}}$ levels of Xe atoms adsorbed on various surfaces. The binding-energy shifts are used to distinguish between (a) Pd- and Pt-like adsorption sites on Pd-Pt surfaces, (b) the 5\ifmmode\times\else\texttimes\fi{}1 and 1\ifmmode\times\else\texttimes\fi{}1 modification of an Ir(100) surface, and (c) step sites and terrace sites on a stepped Ru(0001) surface. The findings are ascribed to local work-function effects and to initial- and final-state orbital energy effects. Xe atoms are thus a very sensitive, local, surface probe.

Influence of the Local Surface Structure on the 5 p Photoemission of Adsorbed Xenon

Surface and electrochemical characterization of electrodeposited PtRu alloys

The growth of vapor deposited palladium on a well-ordered thin alumina film grown on a Ni3Al(111) surface was studied as a function of the sample temperature during deposition and the palladium flux. The superstructure of the oxide film turns out to be an excellent template for the growth of nanostructured palladium cluster arrays. By taking advantage of the growth steering properties of the alumina film we were able to prepare nearly perfectly ordered hexagonal arrays of palladium clusters with a uniform distance of 4.5 nm between the particles. Furthermore the dependence of the cluster height and diameter on the sample voltage as measured by STM has been investigated. In the range between 0.7 V and 2.0 V the measured cluster heights are nearly independent of the sample voltage whereas at voltages higher than 2 V they are continuously decreasing.

Klaus Wandelt

Papers

2 pi resonance features in the electronic spectra of chemisorbed CO.

An X-ray photoelectron spectroscopy study of the chemical changes in oxide and hydroxide surfaces induced by Ar+ ion bombardment

Influence of the Local Surface Structure on the 5 p Photoemission of Adsorbed Xenon

Surface and electrochemical characterization of electrodeposited PtRu alloys

Thin alumina films on Ni3Al(111): A template for nanostructured Pd cluster growth