In the last 30 days

• Open/close Modelling optical spin pumping of a single Mn atom in a CdTe quantum dot

  C L Cao et al  2010 J. Phys.: Conf. Ser. 210 012046 Tag this article

  Article References Full text PDF (607 KB)

  We present a model for the incoherent spin dynamics of a Mn atom inside a CdTe quantum dot resonantly pumped by a laser light. The relevant quantum states of the system, 2 S + 1 = 6 spin states in the optical ground state and the 24 = (2 S + 1) * (2 S _e + 1) * (2 S _h + 1) are obtained from a effective spin Hamiltonian which describes the basic features of photoluminescence. The model includes the dominant Ising exchange interactions between the spins of the hole, the Mn and the electron but neglects coherent spin-flip terms. The Mn spin dynamics is described with a master equation for the populations of the 30 levels for which dissipative spin-flip processes are permitted. The optical spin pumping observed experimentally is explained if the Mn spin relaxation time in with ( T _{1 X}) exciton is much shorter than ( T _{1 G}), the Mn spin relaxation time without exciton.

• Open/close Experimentally observed effects of yaw misalignment on the inflow in the rotor plane

  W Haans et al  2007 J. Phys.: Conf. Ser. 75 012012 Tag this article

  Article References Full text PDF (858 KB)

  Near-wake measurements, focussed on yawed flow conditions, are conducted on a wind turbine rotor model in an open jet wind tunnel. Tip vortex center locations and phase-locked average flow velocity distributions are recorded. Experimental conditions at the blade are not measured and hence are estimated from a measurement analysis tool, named inverse vortex wake model. The unknown bound circulation is derived by the vortex wake type method without the need for an airfoil model. The analysis of the effects yawed operating conditions have on the blade flow conditions concentrates on the individual contributions of tip, root, trailed and shed vortices to the inflow in the rotor plane.

• Open/close X-ray Tomographic Microscopy at TOMCAT

  F Marone et al  2009 J. Phys.: Conf. Ser. 186 012042 Tag this article

  Article References Full text PDF (861 KB)

  Synchrotron-based X-ray Tomographic Microscopy is a powerful technique for fast non-destructive, high resolution quantitative volumetric investigations on diverse samples. At the TOMCAT (TOmographic Microscopy and Coherent rAdiology experimenTs) beamline at the Swiss Light Source, synchrotron light is delivered by a 2.9 T superbend. The main optical component, a Double Crystal Multilayer Monochromator, covers an energy range between 8 and 45 keV. The standard TOMCAT detector offers field of views ranging from 0.75×0.75 mm ² up to 12.1×12.1 mm ² with a pixel size of 0.37 μm and 5.92 μm, respectively. In addition to routine measurements, which exploit the absorption contrast, the high coherence of the source also enables phase contrast tomography, implemented with two complementary techniques (Modified Transport of Intensity approach and Grating Interferometry). Typical acquisition times for a tomogram are in the order of few minutes, ensuring high throughput and allowing for semi-dynamical investigations. Raw data are automatically post-processed online and full reconstructed volumes are available shortly after a scan with minimal user intervention.

• Open/close The vibrational excitation of hot molecules by low energy electron impact

  H Kato et al  2010 J. Phys.: Conf. Ser. 204 012002 Tag this article

  Article References Full text PDF (560 KB)

  We report vibrational excitation functions and angular distributions for electron scattering from the ground vibrational quantum (000), the bending vibrational quantum (010) and the unresolved first bending overtone (020) and symmetric stretch (100) modes of the ground-electronic state in hot (750 K) carbon dioxide (CO ₂) molecules. The excitation function measurements were carried out at incident electron energies in the range of 1–9 eV, and at the electron scattering angles of 30°, 60°, 90° and 120°.

• Open/close On the spectroscopy of quantum dots in microcavities

  F P Laussy and E del Valle  2010 J. Phys.: Conf. Ser. 210 012018 Tag this article

  Article References Full text PDF (2.28 MB)

  At the occasion of the OECS conference in Madrid, we give a succinct account of some recent predictions in the spectroscopy of a quantum dot in a microcavity that remain to be observed experimentally, sometimes within the reach of the current state of the art.

• Open/close Polymer chemistry and hydrogel systems

  E H Schacht  2004 J. Phys.: Conf. Ser. 3 22 Tag this article

  Article References Full text PDF (188 KB)

  Hydrogels are an interesting class of materials that can be prepared by a variety of methods. The properties of these materials depend on their building blocks and the preparation procedures and can be largely varied.

  Among the various classes of hydrogels, are the gels based of physically structuring biopolymers, like gelatine. By chemically modifying these biopolymers, hydrogels with a dual crosslinkage (physical and chemical) can be prepared.

  Hydrogels serve a broad range of applications, including biomaterials, matrices for drug delivery and scaffolds for tissue engineering.

• Open/close Surface photovoltage and photoluminescence spectroscopy of self-assembled InAs/InP quantum wires

  V Donchev et al  2010 J. Phys.: Conf. Ser. 210 012041 Tag this article

  Article References Full text PDF (412 KB)

  The optical properties of InAs/InP multi-layer quantum wire (QWR) structures of various spacer thicknesses have been investigated by means of room temperature surface photovoltage and photoluminescence spectroscopy. Combined with empirical tight binding calculations, the spectra have revealed transitions assigned to QWR families with heights equal to integer number of 5, 6 and 7 monolayers. From the comparison of the experimental and theoretical results the atomic concentration of phosphorus in the wires has been estimated.

• Open/close Effective field theory with differential operator technique for dynamic phase transition in ferromagnetic Ising model

  Takehiro Kinoshita et al  2009 J. Phys.: Conf. Ser. 150 042091 Tag this article

  Article References Full text PDF (400 KB)

  The non-equilibrium phase transition in a ferromagnetic Ising model is investigated by use of a new type of effective field theory (EFT) which correctly accounts for all the single-site kinematic relations by differential operator technique. In the presence of a time dependent oscillating external field, with decrease of the temperature the system undergoes a dynamic phase transition, which is characterized by the period averaged magnetization Q, from a dynamically disordered state Q = 0 to the dynamically ordered state Q ≠ 0. The results of the dynamic phase transition point T _c determined from the behavior of the dynamic magnetization and the Liapunov exponent provided by EFT are improved than that of the standard mean field theory (MFT), especially for the one dimensional lattice where the standard MFT gives incorrect result of T _c = 0 even in the case of zero external field.

• Open/close Giant magnetoresistance effect detection of magnetization reversal in single crystalline nanowires

  H Yamamoto et al  2010 J. Phys.: Conf. Ser. 200 042028 Tag this article

  Article References Full text PDF (411 KB)

  The controllable and rapid magnetization reversal in nano-scale wires is fundamental to the operation of new magnetic logic and data storage devices. A lot of previous investigations for the single domain wall (DW) dynamics in nano-scale wires have been performed by soft ferromagnetic material such as polycrystalline permalloy with negligible magnetic crystalline anisotropy. In fact, it is vital to understand the DW dynamics within the crystalline anisotropy for not only the fundamental magnetism but also potential applications. The aim of this study is to present the experimental result of magnetization reversal in epitaxial single crystalline nanowires by using giant magnetoresistance effect. The DW at the edge of the wire, and the switching field strongly depends on the crystalline anisotropy.

• Open/close Binding energy of exciton in a nanowire superlattice in magnetic and electric fields

  J E Galván-Moya et al  2010 J. Phys.: Conf. Ser. 210 012039 Tag this article

  Article References Full text PDF (410 KB)

  We study the binding energy of excitons in a cylindrical GaAs/Ga _1−xAl _xAs nanowire superlattice, embedded in Ga _1−yAl _yAs matrix, in the presence of magnetic and electric fields applied parallel to the growth direction. We express the exciton trial function as a product of one-particle wave functions of the electron and the hole with variationally determined envelope function, which describes the exciton intrinsic properties and depends only on the electron-hole separation. By using a functional derivative technique, we derive a differential equation for this envelope function, which we solve numerically. By varying the wire radius, interwell barrier width and well sizes we obtain binding energies ranging in character from one for strongly coupled superlattice to that for a system of stack of isolated disks. The behaviour of the binding energies and the charge distributions as functions of the interwell coupling, well sizes, and the external fields is consistently described with our simple formalism.