In the last 30 days

• Open/close Application of non-thermal plasma on gas cleansing

  M Pacheco et al  2008 Phys. Scr. 2008 014017 Tag this article

  Article References Full text PDF (421 KB)

  Non-thermal plasma technologies are an interesting complement or alternative, for some conventional systems used for gas pollution control (i.e. wet scrubbers and catalytic converters) because they are able to remove simultaneously several gas pollutants, with quite good efficiency at a relatively low-energy consumption. In this work, a dielectric barrier discharge was used to remove nitric oxides (NO _x ) and sulfur dioxide (SO ₂) from a mixture of air and water vapor. A chemical model was developed to obtain a toxic gas removal mechanism and to observe the behavior of the species in the plasma. The influence of water vapor addition on the toxic gases removal efficiency is also investigated. Several experimental parameters such as power, frequency, initial concentration of NO _x and SO ₂ were tested and analyzed. Results of numerical simulation demonstrated good agreement with experimental data of the removal process achieving about 95% of efficiency removal of toxic gases studied.

• Open/close Electromagnetic Wave Propagation in an Inhomogeneous Highly Collisional Plasma

  J X Ma  2005 Phys. Scr. 71 540 Tag this article

  Article References Full text PDF (69 KB)

  It is shown that in a highly collisional plasma, electromagnetic waves can propagate beyond the critical density n _c. When the electromagnetic wave propagates obliquely to the plasma density gradient, there exists a critical angle of incidence, below which there is no reflection. When the incident angle is larger than the critical angle, there are two reflection points. One is at a density lower than 2 n _c, corresponding to the EM wave incident from low to high density regions. The other one is at a density higher than 2 n _c, corresponding to that from high to low density regions.

• Open/close Optically controlled semiconductor spin qubits for quantum information processing

  Y Yamamoto et al  2009 Phys. Scr. 2009 014010 Tag this article

  Article References Full text PDF (3.58 MB)

  Implementations of quantum information processing systems based on optically controlled electron spins in semiconductor quantum dots are particulary appealing due to several features. These features include inherent ultrafast gate operation times, reasonably long decoherence times, small optical control power and a natural ability to link to optical fiber communication networks. We will discuss the current state of the art in the experimental implementations of the main elements of semiconductor spin qubits: qubit initialization, single-qubit gates, two-qubit gates, entanglement distribution, projective measurement, quantum memory and indistinguishable single-photon generation.

• Open/close Connection between Coulomb and harmonic oscillator potentials in relativistic quantum mechanics

  Bo Fu et al  2010 Phys. Scr. 81 035001 Tag this article

  Article References Full text PDF (119 KB)

  The Levi-Civita transformation is applied in the two-dimensional (2D) Dirac and Klein–Gordon (KG) equations with equal external scalar and vector potentials. The Coulomb and harmonic oscillator problems are connected via the Levi-Civita transformation. These connections lead to an approach to solve the Coulomb problems using the results of the harmonic oscillator potential in the relativistic systems mentioned above.

• Open/close A general analytical equation for phase diagrams of an N-layer ferroelectric thin film with two surface layers

  Z X Lu et al  2010 Phys. Scr. 81 035004 Tag this article

  Article References Full text PDF (599 KB)

  Within the framework of effective-field theory with correlations, the phase diagrams of an N-layer ferroelectric thin film with two surface layers are studied by the differential operator technique based on the spin-1/2 transverse Ising model. A general analytical equation for the phase diagram of a ferroelectric thin film with arbitrary layer number as well as exchange interactions and transverse fields is derived, and then the effects of exchange interactions and transverse fields on phase diagrams are discussed for an arbitrary layer number N. Meanwhile, the crossover features, from the ferroelectric-dominant phase diagram (FPD) to the paraelectric-dominant phase diagram (PPD), for various parameters of an N-layer ferroelectric thin film with two surface layers are investigated. As a result, an N-independent common intersection point equation is obtained, and the three-dimensional curved surfaces for the crossover values are constructed. In comparison with the usual mean-field approximation, the differential operator technique with correlations reduces to some extent the ferroelectric features of a ferroelectric thin film.

• Open/close A Simple Derivation of the Surface Contribution to the Reflectivity of a Metal, and its Use in the Van der Waals Interaction

  P Apell  1981 Phys. Scr. 24 795 Tag this article

  Article References Full text PDF (1.40 MB)

  The reflection coefficients for light, polarized parallel and perpendicular to the plane of incidence, incident on a translationally invariant jellium surface are derived. The derivation is based on a form of pillbox integration of the two Maxwell equations which normally give the continuity of the parallel field components. In this manner we derive the corrections to the usual Fresnel result due to a varying electron density profile in the surface region. To illustrate the usefulness of these reflection coefficients explicit examples are given for the Van der Waals interaction between an adatom and a solid. The local field at the adatom, the lifetime of an excited adatom and the general form for the Van der Waals interaction incorporating the effects of non-locality in the solid.

• Open/close Bound state solutions of the Klein–Gordon equation with the generalized Pöschl–Teller potential

  Tao Chen et al  2009 Phys. Scr. 79 065014 Tag this article

  Article References Full text PDF (165 KB)

  By employing an improved new approximation scheme to deal with the centrifugal term, we solve approximately the Klein–Gordon equation with equal scalar and vector generalized Pöschl–Teller potentials for the arbitrary orbital angular momentum number l. The bound state energy equation and the unnormalized radial wave functions have been approximately obtained by using the supersymmetric shape invariance approach and the function analysis method. It is found that the present approximate analytical results are in better agreement with those obtained by using the numerical integration approach for small values of α than the approximate results obtained by using the conventional approximation to the centrifugal term.

• Open/close Ultraviolet Absorption Spectrum of the CaH Molecule. IV. On the C-X System

  Birgitta Kaving and Bosse Lindgren  1981 Phys. Scr. 24 752 Tag this article

  Article References Full text PDF (216 KB)

  An investigation of the (1, 0) sequence of the C ²Σ- X ²Σ system of CaH reveals that higher vibrational levels of the C ²Σ state are unlikely to be responsible for the perturbations in the K ²Σ state as earlier presumed. An identification of the (13, 0) band of the D ²Σ- X ²Σ system at 3482 Å is also reported.

• Open/close Refractive Index Measurement and its Applications

  Shyam Singh  2002 Phys. Scr. 65 167 Tag this article

  Article References Full text PDF (223 KB)

  The refractive index of a material is one of the most important optical parameters. In this review article we have discussed different methods and techniques for the measurement of refractive indices of various materials. We have considered the literature of the past two decades from 1980 to 2001 and have shown how the techniques have been developed and improved for the measurement of refractive indices. Some applications of refractive index have also been discussed.

• Open/close Short Channel Effects in MOS-Transistors

  K Björkqvist and T Arnborg  1981 Phys. Scr. 24 418 Tag this article

  Article References Full text PDF (334 KB)

  Metal gate MOS-transistors with channel lengths down to approximately 0.5 μm and with gate oxide thicknesses of 19 nm and 34 nm have been fabricated and evaluated. For devices shorter than 1 μm we have found significant short channel effects on threshold voltage, transconductance and subthreshold current. The experimental results have been compared with computer model calculations. A good agreement between measured and calculated values was found regarding the geometry dependence.