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101.
L. Windholz 《Applied physics. B, Lasers and optics》1995,60(6):573-582
High-resolution laser-atomic-beam spectroscopy allowed us to investigate the lithiumD lines in magnetic and electric fields and to determine hyperfine constants, isotope shifts, scalar and tensor polarizabilities and the absolute transition frequencies with high accuracy. The methods used are discussed and the results are summarized. 相似文献
102.
Microscopy studies on pronton exchange membrane fuel cell electrodes with different ionomer contents
Shuang Ma Claus-Henning Solterbeck Madeleine Odgaard Eivind Skou 《Applied Physics A: Materials Science & Processing》2009,96(3):581-589
Proton Exchange Membrane (PEM) fuel cell electrodes with different ionomer contents were studied with various microscopic
techniques. The morphology and surface potential were examined by Atomic Force Microscopy (AFM) and Kelvin Probe Microscopy
(KPM), respectively. The particulate nature of the electrode was well displayed in the topography and phase images. The particle
and pore size (Z) distributions showed the most frequent values at 30–40 nm and 20–30 nm, respectively. The particle size
corresponds to the size of the carbon support for the platinum catalyst. Catalyst agglomeration was observed in high ionomer
content electrodes. The surface potential images showed distinct difference to the topography images. The overall grain size
was seen to increase, the pore volume to decrease, the surface roughness to decrease, and the surface potential variation
to increase with the increase of ionomer content in the catalyst layer. Transmission electron microscopy (TEM) was carried
out on selective electrodes to provide additional information and confirmed with the AFM results. Cyclic voltammetry (CV)
showed that the electrode containing 30 wt.% ionomer has maximum catalyst utilization. 相似文献
103.
Fano versus Kondo Resonances in a Closed Aharonov-Bohm Interferometer Coupled to Ferromagnetic Electrodes 下载免费PDF全文
Using the Keldysh nonequilibrium Green function and equation-of-motion technique, we investigate Fano versus Kondo resonances in a closed Aharonov-Bohm interferometer coupled to ferromagnetic leads and study their effects on the conductance of this system. The conductance with both parallel and antiparallel lead-polarization alignments is analysed for various values of the magnetic flux. Our results show that this system can provide an excellent spin filtering property, and a large tunnelling magnetoresistance can arise by adjusting the system parameters, which indicates that this system is a possible candidate for spin valve transistors and has important applications in spintronics. 相似文献
104.
A surface acoustic wave can interact with dislocations that are close to the surface. We characterize this interaction and its manifestations as scattered surface acoustic waves for different orientations with respect to the surface of an edge dislocation. For dislocations that are parallel or perpendicular to the free surface, we present an analytical result for short dislocations with respect to the wave-length that reproduce qualitatively the main features observed for dislocations of various sizes. 相似文献
105.
In this contribution, the blending of nano-titanium dioxide (TiO2) and polylactide (PLA) nanofibers has been adopted as a new nanomaterial to facilitate the biorecognition of an anticancer drug daunorubicin. Our observations demonstrate that upon application of the nano-TiO2-PLA polymer nanocomposites, the drug molecules could be readily self-assembled on the surface of the new nanocomposites so that considerably enhanced detection sensitivity for the DNA binding behavior could be observed for the relative biorecognition. These results may also imply some potential valuable application of the blending of nano-TiO2 and PLA nanofibers as a kind of drug carriers in view of the respective good biocompatibility and large surface area of the new nanocomposites. 相似文献
106.
In this paper, the determination of the defects induced by 20 MeV Au irradiations in hexagonal silicon carbide single crystals is discussed. The evolution of the irradiation-induced defects as a function of the ion fluence has been studied as a function of depth below the surface using 0.5-25 keV positron beam based Doppler annihilation-ray broadening spectrometry. Results show the detection of two different kinds of defects, depending on the ion fluence. 相似文献
107.
The concept of Fock space representation is developed to deal with stochastic spin lattices written in terms of fermion operators. A density operator is introduced in order to follow in parallel the developments of the case of bosons in the literature. Some general conceptual quantities for spin lattices are then derived, including the notion of generating function and path integral via Grassmann variables. The formalism is used to derive the Liouvillian of the d-dimensional Linear Glauber dynamics in the Fock-space representation. Then the time evolution equations for the magnetization and the two-point correlation function are derived in terms of the number operator. 相似文献
108.
The Co-doped ZnO powders were synthesized by sol-gel method, and treated at different temperatures (673-873 K) in the presence or absence of NH3 atmosphere for 0.5 and 2 h, respectively. X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) show that better crystal structure can cause larger ferromagnetism and the second phase (Co3O4) is the reason for saturation magnetization decrease of the sample sintered at higher temperature in air. XPS and nuclear magnetic resonance (NMR) prove the existence of Co2+ ions in the Zn0.9Co0.1O and the absence of Co clusters, indicating intrinsic ferromagnetism of the samples treated in air. However, strong ferromagnetism of the samples annealed in NH3 is ascribed to cobalt nitride formed during annealing. 相似文献
109.
110.
Using a 100 MeV Au beam, the surface roughening kinetics of relaxed Si1−xGex alloy films for x=0.5 and 0.7 are studied by means of ex-situ atomic force microscopy (AFM). Swift heavy ion (SHI) irradiation induced surface roughening behavior is demonstrated using the trend in variation of β as a function of fluence when the data are analyzed in terms of the Edwards-Wilkinson (EW) model. By employing the EW model, the observed surface roughening is explained on the basis of the competition between SHI induced sputtering and smoothening through redeposition of the sputtered atoms. The composition dependent variation of surface morphology with increasing fluence is discussed in the light of the strain distribution along the sample surface. 相似文献