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Journal of Applied Physics : Reflection chromaticity of multilayer...

By: E. M. Nascimento, I. N. de Oliveira, and M. L. Lyra

Description: We investigate the chromaticity of the light reflected by multilayered structures containing cholesteric liquid crystals (ChLCs). We considered a single-pitched ChLC multilayered system with quasiperiodic Fibonaccian phase defects as well as an alternate sequence of single-pitched ChLC and isotropic dielectric layers. Using the Berreman 4×4 matrix formalism, we numerically obtain the reflection spectrum and the chromaticity diagram of these structures. The a...

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Journal of Applied Physics : Charge dynamics in ionic polymer meta...

By: Maurizio Porfiri

Description: In this paper, we study the charge dynamics in ionic polymer metal composites (IPMCs) in response to a voltage difference applied across their electrodes. We use the Poisson–Nernst–Planck equations to model the time evolution of the electric potential and the concentration of mobile counterions. We present an analytical solution of the nonlinear initial-boundary value problem by using matched asymptotic expansions. We determine the charge and electric potent...

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Applied Physics Letters : Ferromagnetic structurally disordered Zn...

By: K. Potzger, Shengqiang Zhou, Qingyu Xu, A. Shalimov, R. Groetzschel et al

Description: We present superparamagnetic clusters of structurally highly disordered Co–Zn–O created by high fluence Co ion implantation into ZnO (0001) single crystals at low temperatures. This secondary phase cannot be detected by common x-ray diffraction but is observed by high-resolution transmission electron microscopy. In contrast to many other secondary phases in a ZnO matrix, it induces low-field anomalous Hall effect and is thus a candidate for magnetoelectronics applications.

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The Journal of Chemical Physics : Intermolecular vibrations of dif...

By: J. Ceponkus, P. Uvdal, and B. Nelander

Description: Far infrared spectra of seven different isotopologs of the water dimer have been measured in neon matrices at 2.8 K. The experiments are interpreted with the aid of density functional theory calculations, in particular the calculated harmonic isotopic shifts were utilized. All six intermolecular vibrational modes of the water dimer and the fully deuterated water dimer are assigned based the isotopic shifts induced. 31 of a total of 42 intermolecular fundamen...

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Journal of Applied Physics : Simultaneous real-time x-ray diffract...

By: D. Smeets, J. Demeulemeester, D. Deduytsche, C. Detavernier, C. M. Comrie et al

Description: When the Kissinger method is used to investigate thin film growth kinetics, activation energies obtained are often significantly higher than those of Arrhenius plots based on isothermal studies. The reason for the higher activation energies is related to the sensitivity of the Kissinger analysis to nucleation effects. In fact, this often undesirable effect opens the possibility of studying nucleation barriers in a semiquantitative way. Furthermore, we show t...

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Journal of Applied Physics : Magnetoelectric properties of core-sh...

By: Rashed A. Islam, Vishwas Bedekar, Narayan Poudyal, J. Ping Liu, and Shashank Priya

Description: In this study, we report results on magnetoelectric (ME) core-shell Pb(Zr,Ti)O3 (PZT)-NiFe2O4 (NF) particulate nanocomposites. NF particles forming the shell had size in range of 20–30 nm. The grain size of sintered nanocomposites was found to be in the range of 500–800 nm. The sintered nanocomposite exhibited piezoelectric coefficient (d33) of 60 pC/N, dielectric constant of 865, and ME coefficient of 195 mV/cm Oe. High ME coefficient was observed for wide ...

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Chaos : Stability and multiple bifurcations of a damped harmonic o...

By: Yongli Song, Tonghua Zhang, and Moses O. Tadé

Description: We investigate the dynamics of a damped harmonic oscillator with delayed feedback near zero eigenvalue singularity. We perform a linearized stability analysis and multiple bifurcations of the zero solution of the system near zero eigenvalue singularity. Taking the time delay as the bifurcation parameter, the presence of steady-state bifurcation, Bogdanov–Takens bifurcation, triple zero, and Hopf-zero singularities is demonstrated. In the case when the system...

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Journal of Applied Physics : Comparison of sensitivities of carbon...

By: Masuhiro Abe, Katsuyuki Murata, Tatsuaki Ataka, and Kazuhiko Matsumoto

Description: The sensitivities of biosensors using top-gate-type carbon nanotube field-effect transistors (CNT-FETs) with and without a top metal gate were compared. The CNT-FET biosensor without the top metal gate (sensor I) showed about three times higher transconductance than the one with the top metal gate (sensor II) when they were modulated by a reference gate electrode placed in a solution. Further, the sensitivity of sensor I was three times higher than sensor II...

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Biblioteca Hispanica : Course Methodical Popular Notions of Natura...

By: Jose Maria Paniagua
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Review of Scientific Instruments : Velocity map imaging in time of...

By: M. Brouard, E. K. Campbell, A. J. Johnsen, C. Vallance, W. H. Yuen et al

Description: A new variation on time of flight mass spectrometry is presented, which uses a fast framing charge coupled device camera to velocity map image multiple product masses in a single acquisition. The technique is demonstrated on two photofragmentation processes, those of CS2 and CH3S2CH3 (dimethyldisulfide) at a photolysis wavelength of 193 nm. In both cases, several mass fragments are imaged simultaneously, and speed distributions and anisotropy parameters are ...

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Review of Scientific Instruments : Measurement of shock wave unste...

By: D. Estruch, N. J. Lawson, D. G. MacManus, K. P. Garry, and J. L. Stollery

Description: A new method to measure shock wave unsteadiness is presented. Time-resolved visualizations of the flow field under investigation are obtained using a high-speed schlieren optical system and the motion of the shock wave is determined by means of digital image processing. Information on the shock’s unsteadiness is subsequently derived with Fourier analysis. A sample study on shock unsteadiness in a shock-wave/turbulent boundary-layer interaction with separatio...

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Review of Scientific Instruments : High-resolution Rydberg tagging...

By: Brant Jones, Jingang Zhou, Lei Yang, and C. Y. Ng

Description: By coupling a comprehensive tunable vacuum ultraviolet (VUV) laser system to a velocity-mapped ion imaging apparatus, we show that high-resolution high-n Rydberg tagging time-of-flight (TOF) measurements of nascent atomic photofragments formed by laser photodissociation can be made using single-photon VUV laser photoexcitation. To illustrate this single-photon Rydberg tagging TOF method, we present here the results of the VUV laser high-n Rydberg tagging TOF...

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Journal of Applied Physics : Modification of emission of CdTe nano...

By: Sergei G. Romanov, Maria Bardosova, Ian M. Povey, C. M. Sotomayor Torres, Martyn E. Pemble et al

Description: A light source on the surface of a slab of 2+1-dimensional photonic crystal has been prepared by the Langmuir–Blodgett deposition of a colloidal crystal on top of a thin film containing CdTe nanocrystals. The directional enhancement of the light emission intensity in the spectral range of the photonic bandgap has been revealed through the comparative examination of the angle-resolved transmission, diffraction, and photoluminescence spectra of the prepared st...

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Biblioteca Hispanica : Memory Read at the University of Madrid for...

By: Manuel López González

Description: Leveling

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Journal of Mathematical Physics : Classical limit for semirelativi...

By: Gonca L. Aki, Peter A. Markowich, and Christof Sparber

Description: We consider the three-dimensional semirelativistic Hartree model for fast quantum mechanical particles moving in a self-consistent field. Under appropriate assumptions on the initial density matrix as a (fully) mixed quantum state we prove by using Wigner transformation techniques that its classical limit yields the well known relativistic Vlasov–Poisson system. The result holds for the case of attractive and repulsive mean-field interactions, with an additi...

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Physics of Plasmas : Physics of collisionless phase mixing

By: D. Tsiklauri and T. Haruki

Description: Previous studies of phase mixing of ion cyclotron (IC), Alfvénic, waves in the collisionless regime have established the generation of parallel electric field and hence acceleration of electrons in the regions of transverse density inhomogeneity. However, outstanding issues were left open. Here we use the 2.5 D, relativistic, fully electromagnetic particle-in-cell code and an analytic magnetohydrodynamic (MHD) formulation, to establish the following points: ...

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Physics of Plasmas : Acoustic solitary waves in dusty and/or multi...

By: Frank Verheest, Manfred A. Hellberg, and Ioannis Kourakis

Description: Large nonlinear acoustic waves are discussed in a four-component plasma, made up of two superhot isothermal species, and two species with lower thermal velocities, being, respectively, adiabatic and cold. First a model is considered in which the isothermal species are electrons and ions, while the cooler species are positive and/or negative dust. Using a Sagdeev pseudopotential formalism, large dust-acoustic structures have been studied in a systematic way, ...

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Journal of Applied Physics : Characterization of a controlled plas...

By: A. Flacco, A. Guemnie-Tafo, R. Nuter, M. Veltcheva, D. Batani et al

Description: We present experimental and numerical results on the formation of a controlled plasma density gradient in front of a solid target irradiated with a subpicosecond, moderate intensity laser pulse. Interferometry with femtosecond probe is used to map the temporal evolution of the spatial density distribution of the generated plasma. Experimental results are found to be in good agreement with 1D1/2 hydrodynamic simulations. Moreover, these numerical simulations ...

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Journal of Applied Physics : Cathode effects in cylindrical Hall t...

By: E. M. Granstedt, Y. Raitses, and N. J. Fisch

Description: Stable operation of a cylindrical Hall thruster has been achieved using a hot wire cathode, which functions as a controllable electron emission source. It is shown that as the electron emission from the cathode increases with wire heating, the discharge current increases, the plasma plume angle reduces, and the ion energy distribution function shifts toward higher energies. The observed effect of cathode electron emission on thruster parameters extends and c...

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Journal of Applied Physics : Raman spectra analysis for Ca(B1/3'B2...

By: M. S. Fu, X. Q. Liu, and X. M. Chen

Description: Ca[(Mg1/3Ta2/3)1−xTix]O3 (hereafter denoted as CMTT) and (Ca1−0.39xNd0.26x) [(Mg1/3Nb2/3)1−xTix]O3 (hereafter denoted as CNMNT) complex perovskite ceramics were studied by Raman spectroscopy combined with Rietveld analysis. The crystal structures changed from monoclinic structure with P21/c space group to orthorhombic structure with Pbnm space group for both systems. The main structure of the two systems was orthorhombic and the characteristic modes for the ...

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