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101.
Peter Gaal Daniel Schick Marc Herzog André Bojahr Roman Shayduk Jevgeni Goldshteyn Wolfram Leitenberger Ionela Vrejoiu Dmitry Khakhulin Michael Wulff Matias Bargheer 《Journal of synchrotron radiation》2014,21(2):380-385
A new concept for shortening hard X‐ray pulses emitted from a third‐generation synchrotron source down to few picoseconds is presented. The device, called the PicoSwitch, exploits the dynamics of coherent acoustic phonons in a photo‐excited thin film. A characterization of the structure demonstrates switching times of ≤ 5 ps and a peak reflectivity of ~10?3. The device is tested in a real synchrotron‐based pump–probe experiment and reveals features of coherent phonon propagation in a second thin film sample, thus demonstrating the potential to significantly improve the temporal resolution at existing synchrotron facilities. 相似文献
102.
Mihaela Popovici Johan Swerts Kazuyuki Tomida Dunja Radisic Min‐Soo Kim Ben Kaczer Olivier Richard Hugo Bender Annelies Delabie Alain Moussa Christa Vrancken Karl Opsomer Alexis Franquet Malgorzata A. Pawlak Marc Schaekers Laith Altimime Sven Van Elshocht Jorge A. Kittl 《固体物理学:研究快报》2011,5(1):19-21
Crystalline rutile TiO2 films were grown by atomic layer deposition on oxidized Ru electrodes using a titanium methoxide as the metal precursor and O3 as the oxidant. A protective layer of ~0.3 nm TiO2 grown with H2O as the oxidant was first deposited in order to avoid etching of the Ru bottom electrode by the O3 used for the growth of the TiO2 (bulk) layer. Electrical evaluation of the capacitor stacks with TiO2 as dielectric, RuO2/Ru and Pt as the bottom and top electrodes respectively, resulted in superior characteristics of the rutile phase as compared to the anatase. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
103.
Size-exclusion chromatography (SEC) and size-exclusion electrochromatography (SEEC) are chromatographic techniques used to determine molecular mass (weight) distributions (MWD) of polymers. One important step in the data treatment to derive MWD parameters is the modelling of the calibration curves. The calibration curves applied in SEC and SEEC are generally not linear. In this study the modelling of calibration curves is being examined. Different polynomial models have been evaluated and compared, not only for model fit but also for their predictive properties. It was found that sometimes a straight line and sometimes a third-order polynomial model were best. The best model across the effective range (also called linear range) is not always found to be a straight line. The SEEC curves were found to have considerably higher prediction errors than the SEC ones. Reduction of the number of calibration standards to five or six did not greatly affect the predictive properties of the calibration curves, neither in SEC nor in SEEC. 相似文献
104.
Investigation of the hydration process in 3CaO.Al(2)O(3)-CaSO(4) . 2H(2)O-plasticizer-H(2)O systems by X-ray diffraction 总被引:1,自引:0,他引:1
The development of the hydration process in 3CaO.Al(2)O(3)-CaSO(4) . 2H(2)O-H(2)O system is studied by X-ray diffraction in the presence of varying contents of new plasticizer admixtures belonging to the lignosulphonates class (calcium lignosuphonate-LSC) and condensates melamine formaldehyde sulfonated class-MSF (VIMC-11). The plasticizer admixtures were added in proportion of 0.1-1% solid substance. The influence of the plasticizer admixtures on the hydration process with increasing time is observed and it is shown to depend on the nature and content of the admixtures and the reaction time. The strong adsorption of admixtures on the surfaces on the anhydrous or partially hydrated particles of the system can explain the influence of the admixtures upon the kinetics of the hydration process retardation or acceleration. These plasticizer admixtures influence also the evolution of the hydrated compounds and forming of the hardening structure in the 3CaO.Al(2)O(3)-CaSO(4) . 2H(2)O-H(2)O system; their proportion in the system and the considered length of hardening are correlated. In the 3CaO.Al(2)O(3)-CaSO(4) . 2H(2)O-H(2)O system there are two different influences of the plasticizer admixtures upon the hydration process. One is a delaying action, as a result of plasticizer adsorption on the surface of the anhydrous and hydrated compound particles and another one is the intensifying action due to the stronger dispersion of the particles in aqueous medium. 相似文献
105.
N. Popovici M.L. Paramês R.C. Da Silva O. Monnereau P.M. Sousa A.J. Silvestre O. Conde 《Applied Physics A: Materials Science & Processing》2004,79(4-6):1409-1411
Chromium oxides, CrxOy, are of great interest due to the wide variety of their technological applications. Among them, CrO2 has been extensively investigated in recent years because it is an attractive compound for use in spintronic heterostructures. However, its synthesis at low temperatures has been a difficult task due to the metastable nature of this oxide. This is indeed essential to ensure interface quality and the ability to coat thermal-sensitive materials such as those envisaged in spintronic devices. Pulsed Laser Deposition (PLD) is a technique that has the potential to meet the requirements stated above. In this work, we describe our efforts to grow chromium oxide thin films by PLD from Cr8O21 targets, using a KrF excimer laser. The as-deposited films were investigated by X-ray diffraction and Rutherford backscattering spectrometry. Structural and chemical composition studies showed that the films consist of a mixture of amorphous chromium oxides exhibiting different stoichiometries depending on the processing parameters, where nanocrystals of mainly Cr2O3 are dispersed. The analyses do not exclude the possibility of co-deposition of Cr2O3 and a low fraction of CrO2. PACS 81.15.Fg; 75.50.Dd 相似文献
106.
107.
Narcisa Vrinceanu Diana Tanasa Claudia Mihaela Hristodor Florin Brinza Eveline Popovici Daniel Gherca Aurel Pui Diana Coman Andreea Carsmariu Ionut Bistricianu Gianina Broasca 《Journal of Thermal Analysis and Calorimetry》2013,111(2):1107-1119
The research is aimed at synthesis and characterization of nanoscaled zinc oxide particles and their application on linen fibrous supports, for thermal properties. To impart thermal activity to the fibrous nanocomposites, nanoparticles as well as fibrous nanocomposites were produced in different hydrothermal conditions of temperature (90 °C). To characterize the nanoparticles composition, their shape, size, and crystallinity, investigations technique, such as Fourier transformed infrared spectroscopy, scanning electron microscopy, and X-ray powder diffractometry were used. Differential scanning calorimetry analysis profiles were also revealed. The thermal treatment of linen fabrics with nanosized ZnO does not modify significantly their thermal stability. 相似文献
108.
109.
Zusammenfassung Es wird über die Synthese der bisher unbekannten Trithiopyrophosphonate (C6H5)(RO)P(S)–S–P(S)(RO)(C6H5) aus der entsprechenden thiophosphonigen Säure mit Morpholinosulfenylchlorid berichtet. In Anwesenheit von Triäthylamin bilden sich die bisher nicht beschriebenen S-Morpholino-dithiophosphonate, die dem angenommenen Reaktionsmechanismus nach mit Chlorwasserstoff und thiophosphoniger Säure die Trithiopyrophosphonate liefern. Als Vertreter der Schwefelchloride der Thiophosphonsäuren, die sich bei der Umsetzung von S-Morpholino-dithiophosphonate mit HCl bilden, konnte (C6H5)(C2H5O)P(S)–SCl isoliert werden.
A new synthetic route to trithiophosphonates; Reaction mechanism
The synthesis of the unknown trithiopyrophosphonates, (C6H5)(RO)P(S)–S–P(S)(RO)(C6H5), which are formed by the interaction between the corresponding thiophosphonic acid and morpholinosulfenyl chloride, is reported.In the presence of triethylamine the reaction leads to the S-morpholinodithiophosphonates which, corresponding to the assumed reaction mechanism, gives, with hydrogen chloride and thiophosphonic acid the trithiopyrophosphonates.Among the sulfenylchlorides of the thiophosphonic acids which arise by the interaction of S-morpholinodithiophosphonates with hydrogen chloride, only (C6H5)(C2H5O)P(S)–SCl could be isolated.相似文献
110.
To further investigate the Renner-Teller (RT) effect and spin-orbit mixing in the A(1)A(")<--X(1)A(') system of the simplest singlet carbene, HCF, we report a detailed analysis of the K(a) = 1<--0 subband of 2(0) (4) using polarization quantum beat spectroscopy in combination with fluorescence excitation spectroscopy and lifetime measurements. This subband is perturbed both by RT and spin-orbit interactions, which are clearly differentiated due to the order-of-magnitude difference in matrix elements. We show that RT induced mixing with a high vibrational level of X(1)A(') leads to a splitting of this subband, and while the higher energy member is rotationally unperturbed, every line in the lower energy member is perturbed by spin-orbit mixing with background levels of a(3)A("), as evidenced by large (19)F and (1)H hyperfine constants and Lande g factors. In contrast, the higher energy subband exhibits very small Lande g factors and hyperfine constants, which is explained within a model that incorporates only the A(1)A(")-X(1)A(') interaction. We thus demonstrate that polarization quantum beat spectra provides efficient discrimination between RT and spin-orbit interactions. Analysis of the lower energy subband in concert with ab initio electronic structure calculations has yielded the first information on the (19)F and (1)H hyperfine structure of the a(3)A(") state and the magnitude of the spin-orbit matrix elements. 相似文献