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Scientific contributions and therein geochemical datasets applied to mantle xenoliths collected from the Jwaneng Diamond Mine in Botswana are very rare, because of the problematic accessibility of the mine and additionally the strong alteration of the xenoliths nodules itself. In this study we present a unique and detailed petrographical, petrological and mineralogical dataset applied to these very extraordinary eclogite nodules from the Jwaneng Diamond Mine. Our results show, for the first time strong evidence for mantle metasomatism in the studied area and additionally we calculated the duration of the mantle metasomatic event, which last ∼100 Ma, based on Mg diffusion profiles in garnet. Furthermore, the outcome of our survey show, that the investigated eclogite nodules, has been affected by a mixture of Group I and Group II kimberlites. The formation of Group I kimberlite was caused by the depleted mantle and the development of the later Group II kimberlite by the enriched mantle. The source of the enriched mantle was probably from a megalith, a remnant of a former oceanic crust related to the eastward subduction from the Scotia arc during Jurassic eras. Emplacement of the later mica rich Group II kimberlite leads finally to the explosive eruption kinetics of the kimberlite and consequently to the supersonic uplift of the diamond bearing host rocks. At this point, our results indicates, that supersonic uplift from the Earth´s mantle to the Earth´s surface of the diamondiferous host rocks took place with an velocity of up to ∼1200 km/h (333 m/s) after mantle metasomatism took place. This outcome is based on OH diffusion profiles around totally embedded cracks in garnet. We corroborate this high estimate through velocities expected from viscous laminar flow driven by the pressure gradient. We also evaluate the velocity given by the conversion of gravitational potential energy into kinetic energy, which gives an upper kinetic limit and implies high velocities through the drag coefficients needed to support the dense diamond bearing rock fragment in the melt. This robust evidence for near-accoustic wave speed velocity challenges our understanding of the basic mechanisms that can generate deep and fast cracks within the Earth. The inferred speed of extraction shows that extreme mechanisms must be at work, which potentially starts as a melt filled propagating elastic crack at depth and during ascent accelerates through bubble feedback into its final explosive state.

Being a material of choice for lightweight armor applications, boron carbide has been intensively studied. Its behavior under pressure was investigated using both theoretical and experimental methods, such as powder X-ray diffraction and vibrational spectroscopy. As there is a discrepancy in experimental observations, in the presented work we studied vibrational properties of commercially available, “nearly stoichiometric” B4C using IR and Raman spectroscopy up to 73 GPa. No phase transitions were found in the entire pressure range. Our results are at odds with the recent report of a phase transition in B4.3C at about 40 GPa.

In the present study single crystals of rhombohedral alpha-B were investigated under pressure to 60 GPa by means of single-crystal X-ray diffraction. The bulk modulus of alpha-B was found to be K=224(7) GPa (K'=3.0(3)). Measurements of interatomic distances as a function of pressure revealed that the intericosahedral two-center two-electron (2c-2e) bonds are almost as stiff as some of intraicosahedral ones. The three-center two-electron (3c-2e) intericosahedral bonds show much higher compliance compared to other bonds in alpha-B. The vibrational properties of alpha-B under pressure were investigated by Raman spectroscopy at pressures up to 160 GPa and IR spectroscopy at pressures up to 53 GPa.

Celitement is a new type of cement that is based on hydraulic calcium-hydrosilicate (hCHS) that possesses a potential for minimizing the ratio C/S from above 3 in OPC down to 1, which significantly reduces the amount of CO$_2$ released during processing. The reaction kinetics of hCHS differs from that of classical clinker phases due to the presence of highly reactive silicate species, which involve silanol groups instead of pure calcium silicates and aluminates and aluminoferrites. In contrast to Portland cement, no calcium hydroxide is formed during hydration, which otherwise regulates the Ca concentration. Without the buffering role of Ca(OH)$_2$ the concentration of the dissolved species c(Ca$^{2+}$) and c(SiO$_4^{4-}$) and the corresponding pH must be controlled to ensure a reproducible reaction. Pure hCHS reacts isochemically with water, resulting in a C-S-H phase with the same chemical composition as a single hydration product, with a homogeneous distribution of the main elements Ca and Si throughout the sample. Here we study via nanoindentation the mechanical properties of two different types of hardened pastes made out of Celitement (C/S=1.28), with varying amounts of hCHS and variable water to cement ratio. We couple nanoindentation grids with Raman mappings to link the nanoscale mechanical properties to individual microstructural components, yielding in-depth insight into the mechanics of the mineralogical phases constituting the hardened cement paste. We show that we can identify in hardened Celitement paste both fresh C-S-H with varying density, and C-S-H from the raw material using their specific Raman spectra, while simultaneously measuring their mechanical properties. Albeit not suitable for phase identification, EDX measurements provide valuable information about the distribution of alkalis, thus further helping to understand the reaction pattern of hCHS., Comment: 32 pages, 8 figures

Raman and IR spectroscopy studies on propane were performed at pressures of up to 40 GPa at ambient temperatures using the diamond anvil cell technique. Propane undergoes three phase transitions at 6.4(5), 14.5(5), and 26.5(5) GPa in Raman spectroscopy and at 7.0(5), 14.0(5), and 27.0(5) GPa in IR spectroscopy. The phase transitions were identified using the Raman and IR splitting modes and the appearance or disappearance of peaks, which clearly corresponded to the changes in the frequencies of the modes as the pressure changed. Our results demonstrate the complex high-pressure behavior of solid propane.

The discovery of Hadean to Paleoarchean zircons in a metaconglomerate from Jack Hills, Western Australia, has catalyzed intensive study of these zircons and their mineral inclusions, as they represent unique geochemical archives that can be used to unravel the geological evolution of early Earth. Here, we report the occurrence and physical properties of previously undetected CO2 inclusions that were identified in 3.36–3.47 Ga and 3.80–4.13 Ga zircon grains by confocal micro-Raman spectroscopy. Minimum P–T conditions of zircon formation were determined from the highest density of the inclusions, determined from the density-dependence of the Fermi diad splitting in the Raman spectrum and Ti-in-zircon thermometry. For both age periods, the CO2 densities and Ti-in-zircon temperatures correspond to high-grade metamorphic conditions (≥5 to ≥7 kbar/~670 to 770 °C) that are typical of mid-crustal regional metamorphism throughout Earth’s history. In addition, fully enclosed, highly disordered graphitic carbon inclusions were identified in two zircon grains from the older population that also contained CO2 inclusions. Transmission electron microscopy on one of these inclusions revealed that carbon forms a thin amorphous film on the inclusion wall, whereas the rest of the volume was probably occupied by CO2 prior to analysis. This indicates a close relationship between CO2 and the reduced carbon inclusions and, in particular that the carbon precipitated from a CO2-rich fluid, which is inconsistent with the recently proposed biogenic origin of carbon inclusions found in Hadean zircons from Jack Hills.

Simulations with the software Synchrotron Radiation Workshop (SRW) for the ANKA infrared (IR) beamlines IR1 and IR2 have shown, that the far-IR and terahertz (THz) edge radiation can interact with the vacuum chamber walls very close to the electron beam. Unfortunately SRW cannot compute wavefronts at large angles of observation and at a close vicinity to the source. As we need to take into account these perturbations for the further propagation of the radiation through the entire beamline optics to the experimental station, we have started to develop our own code. This code can generate the electric and magnetic field vectors by solving Maxwell equations without approximations and without restrictions to the angles of observation or distance to the source. In particular the latter requires that also the magnetic field vectors have to be calculated, to obtain the corresponding photon intensity distribution for situations where the electron beam intersects the observation plane. Moreover it revealed that it is essential to correct for the Coulomb field prior to calculating the photon intensity in cases where the electron beam intersects the observation plane. Therefore our code is not limited to synchrotrons but can also be used for the development of new kinds of IR/THz radiation facilities.

A single crystal of α-Ca2[HSiO4](OH) (α-C2SH) was repeatedly imaged at room temperature with synchrotron mid-infrared microscopy after heating to 310°C, 340°C, 370°C, and 400°C respectively. The mechanisms of the observed phase transformations are discussed on the basis of a modular concept of the crystal structures. All images show domains of dellaite, Ca6[Si2O7][SiO4](OH)2, which are predominantly formed in the core of the crystal. In the crystal rim area α-C2SH persists in higher abundance. The mechanism of the phase transformation of α-C2SH into dellaite includes the following: (1) Partial formation of killalaite (Ca3[HSi2O7](OH)) as nuclei according to the isochemical reaction 2Ca2[HSiO4](OH) → Ca3[HSi2O7](OH) + Ca(OH)2 probably induced by anisotropic thermal expansion, local chemical fluctuations, structural (proton) disorder, and different bond strengths of the OH groups in the α-C2SH structure. (2) Further dehydration of killalaite and α-C2SH domains results in the formation of dellaite according to Ca3[HSi2O7](OH) + Ca(OH)2 + Ca2[HSiO4](OH) – 2H2O → Ca6[Si2O7][SiO4](OH)2. The results suggest that the polymerization of two isolated [HSiO4] tetrahedra takes place without dehydration according to reaction (1) rather than through condensation with simultaneous H2O release: 2[HSiO4] → [Si2O7] + H2O. We suggest that reaction (1) cannot be completed at ambient pressure. Thus in the regions close to the rim of the crystals we expect the formation of x-C2S, which starts along the crystal edges according to Ca2[HSiO4](OH) → Ca2SiO4 + H2O. Based on a modular concept, a structural relationship between α-C2SH, killalaite, dellaite, and x-C2S has been established. Similarities and differences in the thermal behavior of α-C2SH and afwillite have been highlighted.

We provide new petrological evidence for the strong influence of water on the formation of the oceanic lithospheric mantle, the subcontinental mantle above, and the continental lithosphere. Our analysis throws new light on the hypothesis that new continental lithosphere was formed by the passage of silicate-rich aqueous fluid through the sub-continental mantle. In order to investigate this hypothesis, we analyzed a representative collection of lherzolite and harzburgite xenoliths from the sample volcano known as “The Thumb”, located in the center of the Colorado Plateau, western United States. The studied sample collection exhibits multi-stage water enrichment processes along point, line and planar defect structures in nominally anhydrous minerals and the subsequent formation of the serpentine polymorph antigorite along grain boundaries and in totally embedded annealed cracks. Planar defect structures act like monomineralic and interphase grain boundaries in the oceanic lithosphere and the subcontinental mantle beneath the North American plate, which was hydrated by the ancient oceanic Farallon plate during the Cenozoic and Mesozoic eras. We used microspectroscopical, petrological, and seismological techniques to confirm multi-stage hydration from a depth of ∼150 km to just below the Moho depth. High-resolution mapping of the water distribution over homogeneous areas and fully embedded point, line and planar defects in olivine crystals of lherzolitic and harzburgitic origin by synchrotron infrared microspectroscopy enabled us to resolve local wet spots and thus reconstruct the hydration process occurring at a depth of ∼150 km (T ≈ 1225 °C). These lherzolites originated from the middle part of the Farallon mantle slab; they were released during the break up of the Farallon mantle slab, caused by the instability of the dipping slab. The background hydration levels in homogeneous olivines reached ∼138 ppm wt H2O, and the water concentration at the planar defects could reach up to ∼1000 ppm wt H2O. However, the formation of antigorite in grain boundaries was found to be the primary hydration mechanism for harzburgitic samples originating from the subcontinental mantle (for hydration, T ≈ 600 °C). Additionally, the formation of antigorite in lherzolites could be found in annealed cracks. From these observations, we conclude that hydration induces multi-stage water enrichment of the mantle wedge by a process that is dominated by the growth and movement of ubiquitous cracks, which acts as planar defects. Cracks in the mantle seem to be the an important feature in both the water cycle of the subduction zone and the formation of the continental lithosphere.

The pozzolanic reaction of a natural zeolite-rich tuff and portlandite was investigated by means of IR spectroscopy. The zeolite tuff consisted mainly of Ca-rich clinoptilolite. A detailed analysis of the changes in the bonding environment during reaction presented by the IR spectra showed that the vibrations assigned to the reactant phases were progressively consumed and implied that Si-rich environments were preferentially depleted. The contemporaneous appearance and rise of vibration bands characteristic for calcium-silicate-hydrates and calcium-aluminate-hydrates demonstrated the formation of reaction products. Changes in bonding environment were spatially visualized by means of synchrotron-IR microspectroscopy. Promising results showed the distribution of reactants and reaction products and allowed to analyze spatial trends in IR-vibration frequencies. A shift in calcium-silicate-hydrate mean peak position from 972 to 968 cm −1 indicated a decrease in silicate chain length with increasing distance from the clinoptilolite-matrix interface.

Polarized synchrotron-based attenuated total-reflection infrared (ATR–IR) spectra of crystals of natural zircon of various origins and degree of disorder are reported. We demonstrate the potential of ATR–IR microspectroscopy for non-destructive structural analysis of zircon microcrystals. Disorder-related IR absorption at wavenumbers lower than the bands arising from the fundamental A 2u [ν 3 (SiO 4 )] and E u [ν 3 (SiO 4 )] zircon modes was observed, which reveals the existence of spatial regions with abundant SiO 4 tetrahedra with longer bonds. A pronounced peak near 990 cm −1 is indicative of an abundance of polymerized SiO 4 tetrahedra. Weak signals in the range 1050–1250 cm −1 show connectivity defects (broken Si–O–Zr bridges) and the existence of shorter Si–O bonds.

The Earth is a wet planet, where water is recycled from the mantle to the surface and back again. The mantle is generally too hot for the stability of hydrous minerals and too cold to store water within significant melt sheets. Therefore, the current paradigm in geosciences is that water resides and moves only through point defects in nominally anhydrous minerals such as olivine, pyroxene and garnet. In the current paper we present the first high-resolution synchrotron images of higher dimensional defect structures within olivine (Mg, Fe)2SiO4 revealing a strong variation of water content. Within single grains water is principally located in “wet spots” around two-dimensional defects such as grain boundaries and cracks. These wet spots are micrometer size clouds of water, which is located within point defects in the olivine crystal structure, around two-D defects with less than nanometre size width. The water is not found in the two-D defects themselves. The results of our study provide new evidence for water-rich microareas developed around monomineralic and interphase mineral boundaries in the lithospheric mantle, here interpreted to preserve images of fracture prior to xenolith eruption. Furthermore our results indicate changes in the chemical composition of the distribution in incompatible elements in minerals, especially towards grain boundaries, which are caused by a fast fluid transfer in the lithospheric crust causing the so-called “cryptic metasomatism”. Our results prompt for a fundamental reassessment of the dynamics of water transfer within the lithospheric mantle above subduction zones. Storage and transfer of water along grain boundaries within nominally anhydrous minerals provides an intermediate reservoir for the dynamic planetary water cycle.

ANKA is a relatively new synchrotron radiation facility at the Forschungszentrum Karlsruhe, a large government research center in the southwest of Germany. The acronym stands for Angstrom Source Karlsruhe. The electron storage ring is 110.4 m in circumference and stores a 2.5 GeV electron beam at a typical current of 200 mA. The facility has been open for users since March 2003.

Terapascal static pressure generation is enabled in laboratory due to implementation of nanocrystralline diamond microballs., Studies of materials’ properties at high and ultrahigh pressures lead to discoveries of unique physical and chemical phenomena and a deeper understanding of matter. In high-pressure research, an achievable static pressure limit is imposed by the strength of available strong materials and design of high-pressure devices. Using a high-pressure and high-temperature technique, we synthesized optically transparent microballs of bulk nanocrystalline diamond, which were found to have an exceptional yield strength (~460 GPa at a confining pressure of ~70 GPa) due to the unique microstructure of bulk nanocrystalline diamond. We used the nanodiamond balls in a double-stage diamond anvil cell high-pressure device that allowed us to generate static pressures beyond 1 TPa, as demonstrated by synchrotron x-ray diffraction. Outstanding mechanical properties (strain-dependent elasticity, very high hardness, and unprecedented yield strength) make the nanodiamond balls a unique device for ultrahigh static pressure generation. Structurally isotropic, homogeneous, and made of a low-Z material, they are promising in the field of x-ray optical applications.

Thermal treatment transforms α-Ca 2 [SiO 3 (OH)](OH) (α-C 2 SH) into hydraulic Ca 2 SiO 4 polymorphs, which is a process of considerable interest to the cement chemistry community. The thermal behavior of differently synthesized samples of α-C 2 SH in air at ambient pressure has been investigated in detail by high-temperature powder X-ray diffraction (XRD), synchrotron-based infrared (IR) microspectroscopy of single crystals, trimethylsilylation method (TMSM), and thermal analysis. Powder XRD data on α-C 2 SH samples heated to different temperatures between 300° and 500°C suggest coexistance of α-C 2 SH and dellaite, Ca 6 [Si 2 O 7 ][SiO 4 ](OH) 2 . IR absorption bands typical for the initial α-C 2 SH phase diminish over the course of thermal treatment, accompanied by the appearance of bands characteristic for dellaite. The partial polymerization of the isolated SiO 3 (OH) tetrahedra present in α-C 2 SH to [Si 2 O 7 ] dimers, as expected for dellaite, was proven by the presence of an IR band at 1050 cm -1 and by TMSM. For the first time, dellaite, along with x-Ca 2 SiO 4 , was observed as an intermediate product of the dehydration of α-C 2 SH. Until now, dellaite was believed to be only a high-pressure phase. Dellaite coexists with x-Ca 2 SiΟ 4 up to 560°-620°C and decomposes to x-Ca 2 SiΟ 4 at higher temperatures. Upon further heating, the latter phase transforms into α'L-Ca 2 SiO 4 , and finally gives β-Ca 2 SiΟ 4 after cooling to room temperature. The thermal decomposition of α-C 2 SH is a much more complicated process than reported previously. Different factors, such as the source of Ca and the presence of NaOH during synthesis, seem to control the mechanism of its dehydration. The presence of dellaite is shown to lower the temperature of formation of β-Ca 2 SiO 4 .

The effects of carbonation of mechanochemically prepared C-S-H samples under ambient conditions for upto 6 months have been investigated by Raman spectroscopy and X-ray diffraction. The type and extent of carbonation are strongly dependent on the initial CaO/SiO2 (C/S) ratio of the samples. Amorphous calcium carbonate hydrate is formed within minutes upon exposure to air. It crystallizes, over time, to give primarily vaterite at C/S >= 0.67 and aragonite at C/S

The gradient of structural alteration and molecular exchange across CO2 laser-irradiated areas in dental enamel was analyzed by Raman and attenuated total reflectance infrared microspectroscopy. The type and the degree of structural changes in morphologically distinguishable zones within the laser spot vary depending on the laser-irradiation parameters—power (1 and 3 W), treatment time (5 and 10 s), and operational mode (super pulse and continuous wave). Using higher power, irrespective of the operation mode, the enamel tissue ablates and a crater is formed. The prevalent phase at the bottom of the crater is dehydrated O-bearing apatite, that is, the fundamental framework topology is preserved. Additional nonapatite calcium phosphate phases are located mainly at the slope of the laser crater. No structural transformation of mineral component was detected aside the crater rim, only a CO3–CO2 exchange, which decays with the radial distance. A lower-power laser irradiation slightly roughens the enamel surface and the structural modification of enamel apatite is considerably weaker for continuous wave than for super pulse mode. Prolonged low-power laser treatment results in recrystallization, and thus structural recovering of apatite might be of clinical relevance for enamel surface treatments. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006

A multidisciplinary approach has been applied to the preparation of antibacterial Ag zeolite/silicone elastomer composites aimed at products that satisfy a range of requirements, namely good mechanical properties after zeolite incorporation and strongly antibacterial. Zeolite X was synthesised and used as antibacterial agent after ion-exchange with silver. The high level of silver (14 wt%) within the zeolite enabled the preparation of antibacterial composites containing a relatively low level of zeolite (2 wt%). The composites showed strong efficacy against Escherichia coli and Staphylococcus epidermidis. Organic functionalization of the zeolite with organo-silanes prior blending with the matrix usefully improved composite mechanical properties and reduced color development in Ag zeolite containing silicone elastomers. Organo-silane modification did not substantially affect the antibacterial performance of the materials; the number of viable cells of both Gram-positive and Gram-negative bacteria was reduced to beyond detection limits within 24 hours of incubation. Efficacy of the Ag zeolite containing composites against the yeast Candida albicans was found to be substantially less than observed with the two bacteria. This study demonstrates that evaluation of polymer composites needs to be performed via a multidisciplinary approach in order to avoid compromising a particular aspect of the materials' design, characteristics or performance, including the use of reliable testing methods to determine the latter.

An infrared microscope equipped with a 64 × 64 pixel focal plane array detector was tested at the infrared beamline of the ANKA synchrotron facility. In contrast to expectations, it was found that the synchrotron beam could illuminate a usefully large area of the array detector while still delivering many times the intensity of illumination with a standard thermal source. The detector delivered excellent signal/noise ratio with a spatial resolution that would be perfectly adequate for many experiments. We conclude that synchrotron infrared microscopy beamlines should be equipped with focal plane array detectors in order to maintain their advantage with respect to similarly equipped benchtop instrumentation.

In this study the intercalation behavior of di- and trivalent cations like Cu(II), Mg(II), Zn(II), and Al(III) into the interlayers of muscovite was investigated by X-ray diffraction and far-infrared spectroscopy. The X-ray diffractometry shows that the original material is a muscovite 2 M1. During the metal cation treatment, new peaks occur at about 1.1 and 2.2 nm, while the original peaks strongly decrease. This gives evidence for the formation of a strongly modified mica structure. The occurrence of bands at low wavenumbers (93 cm−1 and 104 cm−1) in the far-infrared spectra show that the untreated material was partly dehydroxylated. The strong decrease of the band at 93 cm−1 and the occurrence of a band at 110 cm−1 during the intercalation are strong hints about the rehydroxylation of the mineral. The strong increase of the band intensity at 88 cm−1 and the occurrence of a band at 119 cm−1 in the treated muscovites prove the formation of a new, strongly modified mica phase that has both the new cations and the potassium incorporated into the interlayer space.

The region of the electromagnetic spectrum between 0.3 and 20 THz is a “frontier region” of spectroscopy in physics, chemistry, biology, material sciences, and medicine [1]. Radiation in the THz range allows the investigation and excitation of phenomena with time constants of about 1 ps. Examples on this time scale are atomic electron orbits in highly excited Rydberg states, rotations of small molecules and modes of collective oscillations of proteins and polar liquids like water. Resonances of electrons in semiconductor nanostructures and band gaps of superconductors can equally be studied with THz radiation. The THz region lies above the frequencies of traditional electronics but below the range of optical and infrared generators. Until now, possibilities to generate sufficiently intense and brilliant radiation at the wavelengths in question were scarce and the region was therefore named the “THz gap” (Figure 1). In accelerators such highly intense coherent THz radiation can be generated under special c...

The development of the morphology of the rhombohedral {012} faces of jarosite [(K,H3O)Fe3(SO4)2(OH)6] has been observed in situ at the molecular scale in aqueous dissolution experiments using atomic force microscopy (AFM). Synthetically grown rhombohedral surfaces show growth spirals with monolayer steps about 0.5 nm high, corresponding to the d values of the (012) plane. Monolayer-deep etch pits formed on surface terraces during dissolution. The formation and expansion of these etch pits seem to contribute more to the overall dissolution than the retreat of steps that bound terraces. This observation indicates that the dissolution mechanism of jarosite is controlled by surface structure and differs from the step retreat typical for most minerals for which dissolution mechanisms at a molecular level have been investigated. In aqueous solution at pH 5.5, formation of thin, soft overlayers on the jarosite is observed. By adding Na2-EDTA, these overlayers are removed and dissolution takes place mainly by the formation and growth of etch pits. To investigate the influence of H3O+ substitution on the dissolution kinetics, K-dominant jarosite was compared with hydronium jarosite [(H3O)Fe3(SO4)2(OH)6]. Dissolution rates calculated in situ by measuring the vertical position of the surface vs. time on hydronium- and K-dominant jarosite {012} faces in deionized water are 4.41±0.7×10−7 and 1.45±0.98×10−7 mol m−2 s−1, respectively, confirming that H3O+ content on the A site in the structure accelerates jarosite dissolution.

ANKA is a new synchrotron light source atthe Karlsruhe Research Center in southwestGermany. The acronym stands for Angstrom Source Karlsruhe.The ANKA-IR beamline provides a highbrilliance infrared beam through the near,mid and far-infrared range. Thefar-infrared range is of particularinterest, since at frequencies lower thanaround 200 cm-1 (6 THz) synchrotronlight begins to outperform conventionalthermal sources in terms of total intensityas well as brilliance. The extraction ofthe entire flux is a challenge in the THzrange, since the natural verticaldivergence of synchrotron radiationincreases with wavelength and the openingangle for collection is limited by designconstraints. At ANKA-IR, this problem issolved by the collection of radiationemitted from a bending magnet edge source,which has a much smaller verticaldivergence than conventional synchrotronradiation emitted from the constantmagnetic field region within the dipolemagnet. Edge radiation at ANKA permits theextraction of the entire infrared flux downto around 100 cm-1 (3 THz) while withconventional synchrotron radiation thiswould only be the case for frequencies downto 2500 cm-1. ANKA-IR provides usableintensity down to 4 cm-1 (120 GHz).

The growth of K-jarosite was evaluated using scanning electron microscopy (SEM), atomic force microscopy (AFM), and molecular simulations. SEM micrographs show crystals with almost quadratic and, to a minor extent, triangular faces. These were identified to be {0 1 2} and (0 0 1) faces, respectively, using an X-ray single-crystal diffractometer. These results are in agreement with molecular simulations that show that the dipole-free {0 1 2} face is the most stable surface, followed by the (0 0 1) surface, that can lower its dipole moment perpendicular to the surface during relaxation. On the {0 1 2} face, the most stable step directions were identified. From these, an idealized equilibrium growth island can be constructed when the corner energies are minimized by the successive removal of corner ions until a stoichiometric growth island is obtained. Such an equilibrium growth island is the basis for developing a spiral growth model that explains the mechanism of spiral formation as observed using AFM. Furthermore, reactive sites that are potential candidates for the incorporation of foreign ions can be located.

A high-repetition-rate pump–probe experiment is presented, based on the asynchronous sampling approach. The low-α mode at the synchrotron ANKA can be used for a time resolution down to the picosecond limit for the time-domain sampling of the coherent THz emission as well as for hard X-ray pump–probe experiments, which probe structural dynamics in the condensed phase. It is shown that a synchronization of better than 1 ps is achieved, and examples of phonon dynamics of semiconductors are presented.

A synchrotron radiation source emits coherent infrared (IR) radiation when the electron bunch length is comparable to the wavelength of the emitted radiation (see for example [1, 2]). To generate coherent radiation in the far IR (THz) region, a ’low alpha mode’ has been devised at the ANKA storage ring operating at 1.3 GeV. The corresponding lattice has a significantly reduced momentum compaction factor. The spectral dependence of the emitted radiation is recorded at the ANKA-IR beam line, where the synchrotron light is produced in the fringe field of a bending magnet [3]. This edge radiation has the advantage of being more collimated than constant field radiation. This allows the observation of frequencies down to 1 cm-1through a modest vertical aperture, which would not be possible with classical constant field emission due to the increasing beam divergence with decreasing frequency. The onset of coherent emission is found at a synchrotron frequency of about 10 kHz. At 5 kHz, an intensity enhancement of up to 5 orders of magnitude, with respect to the incoherent emission, is observed in the spectral range between 1 and 65 cm-1.

Using vibrational imaging techniques including Fourier-transform infrared (FTIR) synchrotron microscopy,Raman microscopy, and scattering scanning near-field infrared microcscopy (s-SNIM), we mapped a sample of phosphor and copper ions implanted in a high-purity silicon wafer. While Raman microscopy monitors the structural disorder within the implantation fields, the aforementionedinfrared techniques provide a detailed picture of the distribution of the free carriers. On a large scale (tens of micrometers), we visualized the channeling effects of phosphordopants in silicon using FTIRmicroscopy. In comparison, using s-SNIM we were able to image, on a nanometer scale, local variations of the dielectric properties of the silicon substrate due to the activation of copperdopants.

Nano-crystalline calcium silicate hydrates (C-S-H gels) are formed upon hydration of Ca3SiO5 and β-Ca2SiO4, and are therefore the primary hydration products of Portland cements. Raman and IR spectra of a series of mechanochemically prepared C-S-H samples of type C-S-H(1) with Ca/Si ratios ranging from 0.4 to 1.5 reveal changes in structure dependent upon Ca/Si ratio. Finite silicate chains (Q) dominate the structures of the samples at Ca/Si ratios 0.4-1.0, the spectra showing characteristic symmetrical stretching bands between 1010 and 1020cm (R) and asymmetrical stretching around 965cm (IR), with Q units present at Ca/Si 1.00, dimers (Q) are the main building unit of the silicate anionic structure (Raman bands at 890cm, IR band at 945cm). In these samples portlandite is also observed. The similarity of the silicate contribution to the spectra (R and IR) of the samples with Ca/Si = 1.33 and 1.50, and their differing portlandite contents, suggests a similar limit of incorporation of Ca into the C-S-H(I) structure in both phases, which lies under Ca/Si=1.33. In these phases we observe increased ordering of Ca-bonded OH groups. The same trend of increased ordering of the Ca environment is also seen in the development of the intensity and FWHM of the Ca-O band at 332cm (R), 255cm (IR) which is consistent with observations in the Ca2p XPS spectra [2].

The application of lasers in clinical dental practice is becoming increasingly popular, because of the painless, time-saving, and easy-handling treatment of teeth. However, it is still not clear what really happens with the atomic structure of hydroxyapatite under laser irradiation. To study this issue, different spatial areas of laser-treated human enamel and synthetic hydroxyapatite were investigated by Raman and attenuated total reflectance infraredmicro-spectroscopy. The laser-treatment parameters were close to those used in clinical practice. The spectra were collected from spatial areas showing different laser-induced morphological alteration. Inside the laser crater anhydrous calcium phosphate phases are formed, as the degree of structural transformation depends on the applied laser power. In the periphery of the laser spot an exchange of CO3 2to CO2 occurs. When higher laser power is applied, an exchange of molecular groups embedded in hydroxyapatite was detected. In addition, the enhancement of the IR absorption typical for grain-surface OH groups suggests a decrease in the long-range order of apatite crystallites in the periphery of the laser spot. Comparison of spectroscopic data on laserand thermallytreated enamel reveals that inside and in the vicinity of the laser impact region the temperature can reach 1100 K and 700K, respectively. The utilization of super-pulse rather than continuous-wave irradiation mode results in a higher degree of structural alteration and inhomogeneity. m19.p04

Cement is an inorganic hydraulic binder widely used in civil engineering. By the reaction of cement with water calcium-silicate-hydrate (C-S-H) gel is the principal hydration product [1]. For example, buildingmaterials based on Portland cement could contain up to 70 wt% C-S-H gel. Therefore, the structure of the C-S-H gel is responsible for the mechanical properties of the hardened cement paste. The chemical compostion of C-S-H gel varies between the molar CaO/SiO2 (C/S) ratio of 0.5 in older and partly carbonated hardend cement paste and 2.2 in fresh ones. Reaction products (alkali containing C-S-H gels) of the deteriorative alkali-silica-reaction (ASR) show an even lower Ca content. Additionally, these gels have a significant amount of alkalis. Their formation processes and the reaction mechanism of ASR are still unknown and a subject of investigation. To get insights into the structure and formation processes of alkali-C-S-H gels, samples with differerent chemical compositions have been synthesized with the agate-ball milling technique. A part of the gels was converted into their crystalline analogues by hydrothermal treatment. Due to their low crystallinity the gels were investigated with complementary spectroscopic and diffraction methods. Synchrotron based measurements at the diffraction-, XAFSand IR-beamlines at ANKA (Angstromquelle Karlsruhe) were performed. By comparison of the gels and crystalline alkali-C-S-H with XAFS measurements at the Ca absorption edge, it turned out that the Ca environment is stronger affected upon hydrothermal treatment in Ca poor samples than in samples with a higher C/S ratio. Similar results for theK environment were achieved fromXAFS measurements at the K absorption edge. Data from IR spectroscopy show distinct changes in the region of Ca polyhedra vibrations around 240 cm [2]. This result is in good agreement with the XAFS measurements. To point out the role of water in the gels structure the dehydration of C-S-H and alkali-C-S-H was followed in situ with IR-microscopy and the total water loss was analyzed with DTA/TG. The IR data reveal a structural reorganization of the gel. Especially the bands in the Si-O-Si stretching region show distinct changes during the drying process whereas bands attributet to Ca polyhedra vibrations remain largely unchanged.