No abstract

Hard X-ray lens-less microscopy raises hopes for a non-invasive quantitative imaging, capable of achieving the extreme resolving power demands of nanoscience. However, a limit imposed by the partial coherence of third generation synchrotron sources restricts the sample size to the micrometer range. Recently, X-ray ptychography has been demonstrated as a solution for arbitrarily extending the fi eld of view without degrading the resolution. Here we show that ptychography, applied in the Bragg geometry, opens new perspectives for crystalline imaging. The spatial dependence of the three-dimensional Bragg peak intensity is mapped and the entire data subsequently inverted with a Bragg-adapted phase retrieval ptychographical algorithm. We report on the image obtained from an extended crystalline sample, nanostructured from a silicon-on-insulator substrate. The possibility to retrieve, without transverse size restriction, the highly resolved three-dimensional density and displacement fi eld will allow for the unprecedented investigation of a wide variety of crystalline materials, ranging from life science to microelectronics.

The effect of hydrogen implantation in silicon single crystals is studied using high-resolution x-ray scattering. Large strains normal to the sample surface are evidenced after implantation. A simple and direct procedure to extract the strain profile from the scattering data is described. A comparison between different crystallographic orientation of the implanted silicon surface is then presented, namely, for ⟨100⟩, ⟨110⟩, and ⟨111⟩ orientations, showing a dependence that can be related to bond orientation. Effect of annealing on the stressed structure is finally described.

EXAFS spectroscopy, analysed in the frame of the multiple scattering theory, has been able to determine the local structure of [Cu(CO)2]+ complexes hosted inside ZSM-5 channels upon contacting the activated zeolite with CO from the gas phase at room temperature. We found that the number of coordinated CO molecules (1.8 +/- 0.3) is in good agreement with the [Cu(CO)2]+ stoichiometry suggested by IR. The Cu-C distance obtained for the [Cu(CO)2]+ complex is 1.88 +/- 0.02 A, with a C-O distance (1.12 +/- 0.03 A). This work complements a previous one [C. Lamberti, G. Turnes Palomino, S. Bordiga, G. Berlier, F. D'Acapito and A. Zecchina, Angew. Chem. Int. Ed., 2000, 39, 2138], performed at liquid nitrogen temperature, where the structure of [Cu(CO)3]+ complexes was identified by combined EXAFS/XANES/IR spectroscopies. An increase of the Cu-C distance of 0.05 A by moving from [Cu(CO)2]+ to [Cu(CO)3]+ complexes has been observed, which is the local rearrangement needed to accommodate a third CO ligand in the first coordination shell of copper. EXAFS determined that the Cu-C-O bond angle is linear within the error bars (170 +/- 10 degrees), while IR and XANES indicate that intrazeolitic [Cu(CO)2]+ complexes have C2v symmetry. The experimentally obtained moieties are in good agreement with the values obtained with advanced quantum mechanical methods.

Almost all of the world production of vinyl chloride today is based on cracking of 1,2-dichloroethane. For many decades, this compound has been produced by catalytic oxychlorination of ethylene with hydrochloric acid and oxygen [Eq. (1)]. The reaction is performed at 490 ± 530 K and 5 ± 6 atm (1 atm % 1.01 Â 10 5 Pa) using both air and oxygen in fluid-or fixed-bed reactors. [1] C 2 H 4 2 HCl 1 ³2O 2 3 C 2 H 4 Cl 2 H 2 O(1) 24 h, then cooled to 0 8C, and quenched with aqueous hydrochloric acid (3 m, 5 mL). The resulting mixture was warmed to 23 8C and stirred for 30 min, at which point aqueous sodium hydroxide (3 m, 10 mL) was added. The mixture was stirred at 23 8C for 30 min and extracted with diethyl ether (3 Â 20 mL). The combined organic layers were dried over anhydrous sodium sulfate, filtered, and concentrated in vacuo. Column chromatography on silica gel eluting with 30 % diethyl ether in pentane afforded (R)-2-ethyl-2-methyl-2,3-dihydrocinnamyl alcohol 5 a (239 mg, 1.34 mmol, 96 %) as a colorless oil. 1 H NMR (CDCl 3 ): d 7.19 ± 7.31 (m, 5 H), 3.33 (s, 2 H), 2.61 (AB, 2 H, J 24.6 Hz), 1.58 (bs, 1 H), 1.27 ± 1.40 (m, 2 H), 0.93 (t, 3 H, J 7.5 Hz), 0.82 ppm (s, 3 H); 13 C NMR (CDCl 3 ): d 139.0, 130.8, 128.1, 126.2, 68.4, 42.8, 39.1, 29.1, 21.0, 8.3 ppm. High-resolution FAB-MS: m/z (MH): 179.14359 (C 12 H 19 O requires 179.14359).[a] 25 D À 5.9 (c 14.2, CH 2 Cl 2 ). The product was determined to have 94 % ee by HPLC (Chiralcel OD column, eluting with 1 % 2-propanol in hexanes at 0.7 mL min À1 ; R t 20.5 min (major enantiomer), 22.8 min (minor enantiomer)).[21] Greater than two equivalents of electrophile must be added, as the Sand C-alkylations occur at similar rates.[22] The reasons for this dichotomous behavior are unclear. We have been unable to detect significant E/Z isomerization under the reaction conditions. Other effects such as aggregation state and/or different reactive conformations of the E and Z enolates cannot be ruled out.[23] Alkylation of amide enolates with unactivated electrophiles often requires the addition of HMPA or LiCl for useful reaction rates to be observed. For examples see ref.[19] and a

Wafer bonding can be viewed as an example of rough surface adhesion. Although silicon surfaces are among the flattest surfaces available, we will show that formalisms developed to describe rough surface adhesion [1] can be rescaled to nanometer range and applied to silicon wafer bonding, with results that fit well with experimental observations.The models are based on the compression of roughness asperities that balances attractive forces (Fig.1). Different type of models can be considered for the type contact of the asperities (Hertz, JKR, DMT [2]) and for the type of compression (elastic or plastic).The models allow first a prediction of the equilibrium distance between the bonded wafers. This was tested against X-ray reflection experiments, that provide directly this information through the fringe spacing of interface reflectivity (Fig.2).They also predict the real contact area between the wafers. Although this data is more difficult to measure in experiments directly, it is related to the closure of the interface, also measured in X-ray reflection experiments.The real contact area is then correlated to the mean adhesion energy between the wafers. Hence, the results on the interface closure can be matched to the bonding energy values (Fig.3), obtained using other standard techniques such as blade insertion [3] or bonding velocity measurements [4].This allows to build-up a master curve which can be used to measure adhesion energy. References[1] J.A. Greenwood, J.B.P. Williamson, Proc. Roy. Soc. A295, 300 (1966).[2] C. . Fig.1: balance between Van der Waal attraction (solid line) and asperity compression repulsion (dashed line) as calculated using Gaussian roughness models. The equilibrium distance and bond strength can be predicted.Fig.2 X-ray reflection on a bonding interface. The Fringe spacing gives the gap width while the contrast (intensity) gives the closure of the interface 2.5 2.0 1.5 1.0 0.5 0.0 Adhesion energy (J/m 2 ) 1.0 0.8 0.6 0.4 0.2 0.0

The development of microcracks in hydrogen-implanted silicon has been studied up to the final split using optical microscopy and mass spectroscopy. It is shown that the amount of gas released when splitting the material is proportional to the surface area of microcracks. This observation is interpreted as a signature of a vertical collection of the available gas. The development of microcracks is modeled taking into account both diffusion and mechanical crack propagation. The model reproduces many experimental observations such as the dependence of split time upon temperature and implanted dose.

Hydrogen implanted silicon has been studied using high resolution X-ray scattering. Strain induced by implantation has been measured as a function of implantation dose. The dependence of strain with implanted dose shows different regimes starting from linear to quadratic and saturation. The observed strain is consistent with ab-initio and elasticity calculations. Strain rate changes can be associated to the predominant location of hydrogen in bond center location.