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81.
Dynamics of the Dirac fermions, in particular the transmission coefficient and the resonant tunneling lifetime are studied across a bilayer graphene electrostatic double barrier structure modulated by an in plane homogeneous electric field. Asymmetric Fano type resonances are noted for the first time in the transmission spectrum of the bilayer graphene nanostructures and are found to be highly sensitive to the direction of incidence of the charge carriers and the applied homogeneous electric field. The effect of the external field on the extended and the evanescent modes is also analysed. Resonant tunneling lifetime is found to be highly anisotropic in nature. The chiral carriers are either accelerated or decelerated by the electric field depending on the energy of the quasi-bound states, the angle of incidence and the magnitude of the applied field. Effects of the external field on the localization of the chiral carriers are also discussed. 相似文献
82.
M. Daum P. FierlingerB. Franke P. GeltenbortL. Goeltl E. GutsmiedlJ. Karch G. KesslerK. Kirch H.-C. KochA. Kraft T. LauerB. Lauss E. PierreG. Pignol D. ReggianiP. Schmidt-Wellenburg Yu. SobolevT. Zechlau G. Zsigmond 《Physics letters. [Part B]》2011,704(5):456-460
Ultracold neutrons were stored in a volume, using a magnetic dipole field shutter. Radial confinement was provided by material walls. Low-field seeking neutrons were axially confined above the magnetic field. High-field seeking neutrons are trapped inside the magnetic field. They can systematically shift the measured neutron lifetime to lower values in experiments with magnetic confinement. 相似文献
83.
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85.
In 2014, Wang et al. (2014) extended the model of Lou and Wang (2012) to incorporate the credit period dependent demand and default risk for deteriorating items with maximum lifetime. However, the rates of demand, default risk and deterioration in the model of Wang et al. (2014) are assumed to be specific functions of credit period which limits the contributions. In this note, we first generalize the theoretical results of Wang et al. (2014) under some certain conditions. Furthermore, we also present some structural results instead of a numerical analysis on variation of optimal replenishment and trade credit strategies with respect to key parameters. 相似文献
86.
《Analytical letters》2012,45(11):1225-1243
Abstract The use of fluorescence difference decay curves was explored as a way to isolate the decays of components in a complex system. Time-correlated single photon methodology allows one to subtract a “reference” curve from a “sample” curve from a “sample” curve to yield a difference decay curve. To test the feasibility of this method, a model 3-component system (6-carboxyfluorescein, pyranine, and 1-dimethyl-aminoaphtalene-5-sulfonate) was examined. From its complex fluorescence decay curve, the individual decays were obtained by subtracting the appropriate binary solution decay curves. These difference curves coincided with those of the single component systems. Stringent requirements included: use of the same instrumental settings for all solutions, low counting efficiency, avoidance of inner filter effects, absence of energy transfer, and lack of chemical interaction between components. The difference decay method was applied to: 1. Sequential dansylation of serum albumin. Lifetimes of the first two dyes bound are longer than those of the third. 2. Dynamic quenching of quinine fluorescence by chloride ion. When the reference differs from the sample only by having a shorter lifetime, the difference decay curve has a characteristic shape. 3. Quenching of intrinsic protein fluorescence by acrylamide. Bovine serum albumin and liver alchol dehydrogenase were examined. Of the two tryptophans in each protein, one was preferentially quenched and its decay curve was obtained by difference. 相似文献
87.
YANG Peizhi DENG Peizhen HUANG Guosong ZHAO Zhiwei CHEN Wei XU Jun 《Chinese Journal of Lasers》2000,9(1):91-96
1 Introduction Recently,withthedevelopmentofhighperformanceInGaAsdiodelasersinthewavelengthrangebetween0.9and1.1μm[1],greatatte... 相似文献
88.
利用束流能量为116MeV的59Co(35Cl,2p2n)90Mo反应布居90Mo的高自旋态.用10台反康普顿HPGe探测器组成的探测阵列进行γγ符合测量.通过多普勒展宽峰的形状分析测定90Mo高自旋态的寿命.在正宇称衰变系观察到增强的M1跃迁,推断I=13以上是扁椭形变.负宇称高自旋态具有大的B(E2)值,并随自旋增大而起伏变化.正、负宇称态之间的跃迁显示增大的E1跃迁,似有八极关联的可能.但是,90Mo并不处在理论预言的存在八极形变的核区内. 相似文献
89.
GaN激子跃迁的时间分辨光谱学研究 总被引:1,自引:1,他引:0
用时间分辨光谱学方法研究低压有机金属化学汽相沉积生长的GaN中自由,束缚激子(BX)的跃迁,讨论了这些跃迁的光致发光谱,复合寿命及其与温度的关系,给出了中性施主束缚激子和自由激子(FX)的辐射复合寿命分别为0.12ns和0.4ns。 相似文献
90.
One of the key differences of a semiconductor optical amplifier (SOA) with internal lasing oscillation (ILO) from a SOA with external light injection (ELI) lies in a carrier-sharing mechanism. Since the internal lasing mode shares the same pool of carriers with the signals, the carriers (or photons) withdrawn from the circulating laser mode speed up the gain recovery. On the other hand, the external light injected into the SOA shortens the carrier recovery time through optical pumping without any carrier sharing involved. To find out a better scheme, we have made a comparative investigation on the effects of the ILO and ELI on the SOA performance. It turns out by way of simulation that the ELI scheme provides faster gain recovery, shorter carrier lifetime, and higher saturation power when the external injection power is higher than the internal lasing power. The performance enhancement is not so pronounced with the carrier-sharing mechanism, as the internal lasing mode itself gives rise to severe longitudinal spatial hole burning (LSHB). Nevertheless, the ILO scheme is preferable for linear-amplification applications. We also examine the use of the ELI for low-crosstalk optical amplifiers. It is found that the ELI scheme does not bring in a very strong resonance peak in the crosstalk, which appears in a SOA with ILO due to relaxation oscillations of the lasing mode. In comparison to the ILO in SOAs, the ELI into SOAs is likely to leave more optical gain for multi-channel amplification without any sacrifice on the crosstalk. 相似文献