An x-ray transfocator design for the combined use of 1D and 2D compound refractive lenses is described. The device includes stacks of beryllium parabolic lenses with different radii of curvature and provides microfocused x-ray beams in the 4-20 keV photon energy range. The transfocator has been implemented at the P10 Coherence Beamline of the PETRA III synchrotron at DESY, Hamburg. Results of transfocator performance and applications for coherent x-ray scattering experiments are presented. ©2012 Optical Society of AmericaOCIS codes: (340.7460) X-ray microscopy; (120.3620) Lens system design; (030.6140) Speckle; (100.5070) Phase retrieval; (160.5298) Photonic crystals. References and links1. B. Lengeler, C. Schroer, J. Tümmler, B. Benner, M. Richwin, A. Snigirev, I. Snigireva, and M. Drakopoulos, "Imaging by parabolic refractive lenses in the hard x-ray range," J. Synchrotron Radiat. 6(6), 1153-1167 (1999 Mulders, and M. Sutton, "Small-angle X-ray scattering using coherent undulator radiation at the ESRF," J. Synchrotron Radiat. 5(1), 37-47 (1998)

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The gas-chromatographic method is used to study the interaction of water and methanol molecules with active hydrophilic centres existing at the surface of thermally exfoliated graphite and graphitized thermal carbon black. The concentration of carboxyl and phenol hydroxyl groups at the surface of these sorbents is determined, and heats of adsorption of the studied molecules are shown to beQ a = 40−39 and 28−25 kJ/mol, respectively. It is also shown that adsorption of water at the hydrophilic centres at lowest relative pressure values takes place with formation of clusters consisting of n = 2 water molecules.

A complex theoretical-experimental investigation has been carried out on the interaction of water with hydrophilic centers -phenolic and carboxyl groups -on the surface of graphite and graphitized thermal carbon black in low surface occupation range. It is shown that microclusters, formed by the absorption on such centers, have a cyclic structure of 4-5 molecules similar to those observed in liquid water and on the surface of silver iodide. The formation of such structures is shown to be energetically advantageous. It is shown that the generalized Langmuir equation, derived from molecular-statistical considerations, is considerably better over a wide range of relative pressure for the description of the experimental isotherm for the adsorption of water on graphitized thermal carbon black and allows for a better interpretation of structural and energetic characteristics of adsorbed systems obtained by a complex of methods.Graphite and graphitized thermal carbon black (GTC) are suitable models for the study of the interaction of molecules of water with hydrophilic centers in basically hydrophobic adsorbents. The hydrophilic centers found on the surfaces of these molecules are 3-12 nm [1] apart from one another which is considerably greater than the van der Waals diameter of a water molecule (0.3 nm). This permits the study of the interactions of the water molecules with such hydrophilic centers at low to medium coverage of the surface "in a pure form," without complicated appearance of surface (two-dimensional) association.The study of the adsorption of water on carbon adsorbents is associated with a large number of investigations. A detailed review of this work is given, for example, in [2]. In recent years the study of the interaction of water with the surfaces of carbon surfaces, apart from its theoretical value, has acquired an important practical aspect [3][4][5] in connection with the formation of stable sooty aerosols in the upper levels of the troposphere -products of the incomplete combustion of fuels of internal combustion engines. On interaction with water, sooty aerosols not only form cirrus clouds but also appear as condensation nuclei which affect the formation of cloudiness in the troposphere.Since the surface of soot particles is similar in all properties to GTC, then the study of the interaction of water with graphite and GTC permits, if not regulation, then in ever case to predict the negative effect of the formation of cirrus clouds on the radiation balance of atmosphere and the climate of the planet.In this work we present the results of complex gas chromatographic, molecular-statistical, and quantum-chemical investigations of cluster formation of water molecules on the active centers of graphitized thermal carbon black. 0040-5760/07/4303-0191

Possibilities to use the MAXIPIX 2×2 detector for coherent scattering applications are investigated. This study focuses on X-ray Photon Correlation Spectroscopy experiments. Flatfield measurements show that the MAXIPIX detector pixels respond very inhomogeneously in the X-ray range between 5 and 10 keV most commonly used for coherent scattering experiments. Two colloidal model sample systems are investigated using the MAXIPIX and a direct illumination CCD for comparison. It is demonstrated that the MAXIPIX 2 × 2 detector is applicable for static and dynamic coherent scattering experiments after flatfield correction.

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The adsorption of water and other polar substances on to the surface of graphitized carbon black and macroporous silica modified by polymethylhydride silicone has been studied using gas chromatography. The adsorption heat values of the substances studied were determined and the concentration of surface hydrophilic centres estimated. Conclusions have been drawn concerning the number of water molecules adsorbed on to hydrophilic centres at low surface occupation values. In the case of water adsorption on the graphitized carbon black surface, the chromatographic data for the adsorption heat have been compared with the energy of water molecule interaction with the surface clusters modelling the micropores existing on the basal surface of carbon black particles as calculated using quantum chemical methods.