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21.
John?Mann Dezheng?Sun Quan?Ma Jen-Ru?Chen Edwin?Preciado Taisuke?Ohta Bogdan?Diaconescu Koichi?Yamaguchi Tai?Tran Michelle?Wurch KatieMarie?Magnone Tony F.?Heinz Gary L.?Kellogg Roland?Kawakami Ludwig?BartelsEmail author 《The European Physical Journal B - Condensed Matter and Complex Systems》2013,86(5):226
Areas of single-layer MoS2 film can be prepared in a tube furnace without the need for temperature control. The films were characterized by means of Raman spectroscopy, photoluminescence, low-energy electron diffraction and microscopy, and X-ray photoelectron spectroscopy and mapping. Transport measurements show n-doped material with a mobility of 0.26 cm2 V-1 s-1. 相似文献
22.
We study optical analogues of higher-order Dirac solitons (HODSs) in binary waveguide arrays. Like higher-order solitons obtained from the well-known nonlinear Schrödinger equation governing the pulse propagation in an optical fiber, these HODSs have amplitude profiles which are numerically shown to be periodic over large propagation distances. At the same time, HODSs possess some unique features. Firstly, the period of a HODS depends on its order parameter. Secondly, the discrete nature in binary waveguide arrays imposes the upper limit on the order parameter of HODSs. Thirdly, the order parameter of HODSs can vary continuously in a certain range. 相似文献
23.
T. A. Nguyen H. T. Dung 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(1):173-177
Using the Born expansion of the Green tensor, we consider the
spontaneous decay rate of an excited atom placed in the vicinity of
a rectangular plate. We discuss the limitations of the commonly used
simplifying assumption that the plate extends to infinity in the lateral
directions and examine the effects of the atomic dipole moment
orientation, atomic position, and plate boundary and thickness on the atomic
decay rate. In particular, it is shown that
due to the plate finite size, the spontaneous decay may be inhibited
even when the atom is situated very close to the surface, and that
in the boundary region, the
spontaneous decay rate can be strongly modified. 相似文献
24.
Cunefare KA Biesel VB Tran J Rye R Graf A Holdhusen M Albanese AM 《The Journal of the Acoustical Society of America》2003,113(2):881-892
Qualification of anechoic chambers is intended to demonstrate that the chamber supports the intended free-field environment within some permissible tolerance bounds. Key qualification issues include the method used to obtain traverse data, the analysis method for the data, and the use of pure tone or broadband noise as the chamber excitation signal. This paper evaluates the relative merits of continuous versus discrete traverses, of fixed versus optimal reference analysis of the traverse data, and of the use of pure tone versus broadband signals. The current practice of using widely space discrete sampling along a traverse is shown to inadequately sample the complexity of the sound field extant with pure tone traverses, but is suitable for broadband traverses. Continuous traverses, with spatial resolution on the order of 15% of the wavelength at the frequency of interest, are shown to be necessary to fully resolve the spatial complexity of pure tone qualifications. The use of an optimal reference method for computing the deviations from inverse square law is shown to significantly improve the apparent performance of the chamber for pure tone qualifications. Finally, the use of broadband noise as the test signal, as compared to pure tone traverses over the same span, is demonstrated to be a marginal indicator of chamber performance. 相似文献
25.
The van der Waals potential of two atoms in the presence of an arbitrary arrangement of dispersing and absorbing magnetoelectric
bodies is studied. Starting from a polarizable atom placed within a given geometry, its interaction with a second polarizable/magnetizable
atom is deduced from its Casimir-Polder interaction with a weakly polarizable/magnetizable test body. The general expressions
for the van der Waals potential obtained thusly are illustrated by considering first the case of two atoms in free space,
with special emphasis on the interaction between (i) two polarizable atoms and (ii) a polarizable and a magnetizable atom.
Furthermore, the influence of magnetoelectric bodies on the van der Waals interaction is studied in detail for the example
of two atoms placed near a perfectly reflecting plate or a magnetoelectric half space, respectively.
The text was submitted by the authors in English. 相似文献
26.
Optical spectra of highly excited quantum wires at low temperatures have been studied within the dynamical screening approximation. We found a strong Fermi-edge singularity (FES) in the photoluminescence spectra. The spectral shape and FES intensity strongly depend on temperature in agreement with recent experimental results. 相似文献
27.
Dung T. Tran Ian P. Jones Jon A. Preece Roy L. Johnston Coenraad R. van den Brom 《Journal of nanoparticle research》2011,13(9):4229-4237
Dodecanethiol-capped Cu–Au nanoparticles, synthesized via a successive two-phase (water/toluene) and galvanic-exchange procedure,
were characterized using transmission electron microscopy (TEM). The size range of the particles is around 1–7 nm. Electron-induced
morphological evolution was observed under high resolution (HR) TEM. Cuboctahedral morphology was found to be thermodynamically
stable. Electron-induced aggregation of two particles was also observed. Chemical ordering of cuboctahedral particles was
studied by atomic-resolution high angle annular dark field (HAADF) imaging in scanning TEM (STEM) mode and energy dispersive
X-ray (EDX) element mapping using a silicon drift detector (SDD). The particles were found to be Cu–Au mixed, and to be stable
in air. Surface plasmon resonance (SPR), which is dependent on local structure and morphology, was investigated by electron
energy loss spectroscopy (EELS). 相似文献
28.
Jan?HladkyView authors OrcID profile Asaf?NachmiasEmail author Tuan?Tran 《Journal of statistical physics》2018,173(3-4):502-545
Let G be a connected graph in which almost all vertices have linear degrees and let \(\mathcal {T}\) be a uniform spanning tree of G. For any fixed rooted tree F of height r we compute the asymptotic density of vertices v for which the r-ball around v in \(\mathcal {T}\) is isomorphic to F. We deduce from this that if \(\{G_n\}\) is a sequence of such graphs converging to a graphon W, then the uniform spanning tree of \(G_n\) locally converges to a multi-type branching process defined in terms of W. As an application, we prove that in a graph with linear minimum degree, with high probability, the density of leaves in a uniform spanning tree is at least \(e^{-1}-\mathsf {o}(1)\), the density of vertices of degree 2 is at most \(e^{-1}+\mathsf {o}(1)\) and the density of vertices of degree \(k\geqslant 3\) is at most \({(k-2)^{k-2} \over (k-1)! e^{k-2}} + \mathsf {o}(1)\). These bounds are sharp. 相似文献
29.
Intramolecular electron spin exchange as a function of temperature and solvent viscosity and polarity has been studied by
X-band electron paramagnetic resonance (EPR) spectroscopy in two rigid nitroxide biradicals existing in one spatial conformation
only. Temperature variations of the isotropic hyperfine splitting constanta and exchange integral value |J/a| were measured from EPR spectra and subsequently analyzed. The interaction of polar solvent molecules with >N-O fragments
of nitroxide groups led to a slight decrease of the |J/a| value with the increase of temperatureT. In contrast, the interaction of polar solvent molecules with functional groups inside the bridge resulted in a noticeable
increase of |J/a| vs.T. In the last case, a coverse relationship between the values of |J/a| and the hyperfine splitting constanta has been observed for solvents with different polarity. 相似文献
30.
Ngo Ngoc Ha Nguyen Truong Giang Tran Ngoc Khiem Nguyen Duc Dung Tom Gregorkiewicz 《固体物理学:研究快报》2016,10(11):824-827
Photogenerated carriers in Si–Ge alloy nanocrystals (NCs) prepared by co‐sputtering method were investigated by mean of transient induced absorption. The carrier relaxation features multiple components, with three decay life times of τ ≈ 600 fs, 12 ps, and 15 ns, established for Si0.2Ge0.8 alloy NCs of a mean crystal size of 9 nm and standard deviation of 3 nm. Deep carrier traps, identified at the boundary between the NCs and the SiO2 host with the ionization energy of about 1 eV, are characterized by a long‐range Coulombic potential. These are responsible for rapid depletion of free carrier population within a few picoseconds after the excitation, which explains the low emissivity of the investigated materials, and also sheds light on the generally low luminescence of Si/Ge and Ge NCs. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献