共振辐射的理论研究——Holstein方程的解

解决介质中共振辐射的关键问题是求解Holstein方程。本文直接利用算符运算将方程积分,给出了激发态粒子集居数的含无限项的级数表达式。基于对这个级数高阶系数的极限行为的研究,成功地克服了无穷项求和的困难,整理出一个在任意给定精度下都只含有限项的解式,由它可以计算出任何时刻的结果。 关键词：     

Low-temperature results of the statistical theory of noninteracting spin waves

Low-temperature predictions of a free-spin-wave theory that includes the correct spin-wave kinematics for theS=1/2, quantum Heisenberg ferromagnet, as described in a previous paper, are obtained for three dimensions using analytic and Monte Carlo techniques. The low-temperature propagator is found to be of boson form, and the low-temperature magnetization goes asT ^3/2, which agrees with the interacting theory at lowest order inT.     

Mesoporous carbon capsules as electrode materials in electrochemical double layer capacitors

The performance of mesoporous carbon capsules as electrode materials in electrochemical double layer capacitors (EDLCs) was evaluated in the presence of a variety of electrolytes, including room temperature ionic liquids (ILs).     

Mechanisms of stacking fault tetrahedra destruction by gliding dislocations in quenched gold

The destruction processes of stacking fault tetrahedra (SFTs) induced by gliding dislocations were examined by transmission electron microscopy (TEM) in situ straining experiments for SFTs with edge lengths ranging from 10 to 50 nm. At least four distinct SFT destruction processes were identified: (1) consistent with a Kimura–Maddin model for both screw and 60° dislocations, (2) stress-induced SFT collapse into a triangular Frank loop, (3) partial annihilation leaving an apex portion and (4) complete annihilation. Process (4) was observed at room temperature only for small SFTs (～10 nm); however, this process was also frequently observed for larger SFTs (～30 nm) at higher temperature (～853 K). When this process was induced, the dislocation always cross-slipped, indicating only screw dislocations can induce this process.     

Some Aspects of Current Interruption Physics in High Voltage Circuit Breakers

Recent results of experimental and theoretical investigations on current interruption processes are presented with a focus on SF₆ high voltage circuit breakers. Various aspects of thermal interruption at the zero crossing of the current are shown, including the scatter and the distribution of arc voltage shortly before CZ and the role of turbulence. The thermal interruption capability of air and CO₂ are compared to that of SF₆. Investigations on the dielectric recovery are shown for SF₆ and CO₂. The breakdown voltage during the dielectric recovery can be described by simple streamer and leader inception models. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Measurement of the complex dielectric constant of a single gold nanoparticle

A differential interference contrast microscopy technique that employs a photonic crystal fiber as a white-light source is used to measure both the real and the imaginary part of the complex dielectric constant of single 10 and 15 nm gold nanoparticles over a wavelength range of 480 to 610 nm. Noticeable deviations from bulk gold measurements are observed at short wavelengths and for individual particles even after taking into account finite-size surface damping effects.     

Impact parameter dependence ofL- andK-shell excitation in I-Ag collisions

The impact parameter dependence of theL- andK-vacancy production of target and projectile was measured in I-Ag collisions at 40 MeV and 63 MeV in a X-ray particle coincidence experiment. A largeL-vacancy production is found for impact parametersb smaller than theL-shell radius with a pronounced increase forb<250fm. TheL-shell excitation is discussed in terms of 4fσ excitation and vacancy transfer in the 3pσ, 3dπ, 3dσ molecular orbitals through 3pπ-3pσ and 3dδ-3dπ-3dσ rotational-couplings. The 2pσ excitation probability is obtained from the summedK-vacancy production probability, and compared with the prediction of 2pσ excitation in a multiple collision process. The latter is determined by folding the measured IL-shell excitation probability with the impact parameter dependence of the 2pπ-2pσ rotational coupling. The discrepancy observed at small impact parameters suggests an enhanced 2pπ and 2pσ excitation at small impact parameters in a one-collision process. TheL- andK-vacancy sharing probabilities are found to be impact parameter independent over a large impact parameter range.     

Detection and spectroscopy of gold nanoparticles using supercontinuum white light confocal microscopy

We combine confocal microscopy using supercontinuum laser illumination and an interferometric detection technique to identify single nanoparticles of diameter below 10 nm. Spectral analysis of the signal allows us to record the plasmon resonance of a single nanoparticle. Our results hold great promise for fundamental studies of the optical properties of single metal clusters and for their use in biophysical applications.     

Demonstration of Three True Random Number Generator Circuits Using Memristor Created Entropy and Commercial Off-the-Shelf Components

In this work, we build and test three memristor-based true random number generator (TRNG) circuits: two previously presented in the literature and one which is our own design. The functionality of each circuit is assessed using the National Institute of Standards and Technology (NIST) Statistical Test Suite (STS). The TRNG circuits were built using commercially available off-the-shelf parts, including the memristor. The results of this work confirm the usefulness of memristors for successful implementation of TRNG circuits, as well as the ease with which a TRNG can be built using simple circuit designs and off-the-shelf breadboard circuit components.