Dielectric Property Measurement of Gold Nanoparticle Dispersions in the Millimeter Wave Range

A quasi-optical transmission-meter is employed to measure the performance of gold nanoparticle dispersions at the W-band (75-110 GHz). A specifically designed liquid sample holder was integrated into the transmission-meter to secure reliable measurement repeatability and an iterative method was utilized to retrieve the dielectric properties from the measured transmission coefficients. Different to some previous results in MHz and GHz range, it was found that the dielectric properties of purified gold nanoparticle (GNP) dispersions did not exhibit marked difference to that of DI-water, which suggests a weak interaction of GNP with EM radiation in the W-band, consistent to the predictions from the effective medium theory and microscopic views. Further work is proposed to explore the dielectric properties of GNP dispersions in the shorter wavelength, such as sub-terahertz, terahertz and infrared range.     

The Impedance of a Wire Grid Parallel to a Dielectric Interface

Analysis is given for the problem of reflection of a plane wave at oblique incidence on a wire grid which is parallel to a plane interface between two homogeneous dielectrics. It is assumed that the wire grid is a periodic structure and consists of thin cylindrical wires of homogeneous material. The equivalent circuit is derived where it is shown that the space on either side of the interface can by a transmission line, and the grid itself is represented by a pure shunt element across one of the lines.     

Polarizability,Susceptibility, and Dielectric Constant of Nanometer‐Scale Molecular Films: A Microscopic View

The size‐dependence of the polarizability, susceptibility, and dielectric constant of nanometer‐scale molecular layers is explored theoretically. First‐principles calculations based on density functional theory are compared to phenomenological modeling based on polarizable dipolar arrays for a model system of organized monolayers composed of oligophenyl chains. Size trends for all three quantities are primarily governed by a competition between out‐of‐plane polarization enhancement and in‐plane polarization suppression. Molecular packing density is the single most important factor controlling this competition and it strongly affects the bulk limit of the dielectric constant as well as the rate at which it is approached. Finally, the polarization does not reach its “bulk” limit, as determined from the Clausius–Mossotti model, but the susceptibility and dielectric constant do converge to the correct bulk limit. However, whereas the Clausius–Mossotti model describes the dielectric constant well at low lateral densities, finite size effects of the monomer units cause it to be increasingly inaccurate at high lateral densities.     

Polarizability of a Thin Cylindrical Resistive Dipole in a Quasistatic Field

Journal of Communications Technology and Electronics - The problem of polarizability of a cylindrical resistive dipole in a quasistatic field is solved taking into account the skin effect. For the...     

ZST微波陶瓷在介质振荡器上的应用研究

用传统固相法制备ZST(氧化锆-氧化锡-氧化钛)系微波陶瓷,研究了ZST系微波陶瓷的组成对介电性能的影响。通过X-射线衍射(XRD)和HP8714ET网络分析仪对其晶体结构和微波介电性能进行研究,实验结果表明:少量掺Bi2O3的ZST系陶瓷材料可把烧结温度降低至1 260℃,微波介电性能较好;掺入量大于2%(质量分数)时,ZST系微波陶瓷在晶界偏析形成了Bi2Ti2O7新相,微波性能下降。用微波介电性能较好的ZST系陶瓷制成的介质振荡器进行测试,其电性能满足设计要求。     

PC型HgCdTe中记忆效应的激子解释

本文对低温下激光与ＰＣ型ＨｇＣｄＴｅ在激光照射后将产生的记忆效应进行了研究。根据本文提出的激光诱导激子的物理模型，得到了ＰＣ型ＨｇＣｄＴｅ在激光作用时电导率下降是激子对载流子散射的结论。理论计算结果与实验结果基本一致。     

From Atoms to Lives: The Evolution of Nanoparticle Assemblies

Nanoparticle (NP) assemblies have been studied over the past several decades, and the field is advancing more quickly and reaching into more diverse fields. Reports issued from academic and industrial laboratories have driven these advances. Countless breakthroughs have been reported in widely different fields, including thermoelectronics, photoelectronics, catalysts, energy sources, and medical carriers. A “family tree” is clearly needed to accurately trace the developments in the study of NP assemblies. This review uses the unconventional approach of comparing the atomic and NP worlds to describe the development of NP research during the past several decades. The corresponding classifications, such as atoms and NPs, molecules and molecular‐type NP assemblies, crystals and crystalline‐type NP assemblies, biological organisms and analogous artificial assemblies, and biologically functional NP complex assemblies, are discussed in detail. It concludes with remarks concerning the trend from nonliving to living applications of NP assemblies.     

Resonant Frequency Stability of the Dielectric Resonator on a Dielectric Substrate

A simple approximate method for predicting the resonant frequencies of TE modes of dielectric resonators is developed. By using this method, an analytical expression is derived for the resonant frequency stability of the dielectric resonator on a dielectric substrate, and the effect of the substrate on the stability is studied. The result is useful when the high-frequency stability is required.     

On the Suppression of Electron-Hole Exchange Interaction in a Reservoir of Nonradiative Excitons

Semiconductors - Mechanisms of the suppression of the electron-hole exchange interaction in nonradiative excitons with a large in-plane wave vector in high-quality heterostructures with quantum...     

缀饰激子在半导体微腔中的辐射

本文建立了半导体微腔的缀饰激子模型,在ＶＣＳＥＬ器件量子阱中的激子首先通过内电磁场与腔耦合,形成缀饰态。而后作为多粒子过程,缀饰激子与腔内真空场耦合产生辐射。通过ＱＥＤ方法,我们得到偶极子辐射密度方程和系统能量衰 变方程。从方程解的讨论中,我们得到超辐射和偶极子微腔方向 效应的结果,同时预言民当内场耦合足够强时,缀 激子可以直接辐射到一个很的激光模中。     

准二维强耦合激子能量的温度依赖性

采用线性组合算符法和LLP变分法研究了晶格热振动和极化子效应对量子阱中激子与界面光学(IO)声子强耦合又与体纵光学(LO)声子弱、中耦合体系的基态和激发态的影响,推导出作为量子阱宽和温度函数的激子基态能量的移动和第一内部激发态能量的移动的表达式,以AgCl/AgBr/AgCl量子阱为例进行了数值计算.结果表明,由激子IO声子强耦合所产生的激子基态能量移动和第一内部激发态能量移动随温度的升高而增大,而由激子-LO声子弱、中耦合所产生的激子基态能量移动和第一内部激发态能量移动随温度的升高而减小.     

Contribution of a single face to the wedge diffracted field

In certain wedge diffraction problems, it is advantageous to know the part of the diffracted field created by the currents induced on a single face of the wedge. The rigorous solution to the corresponding canonical problem is derived. This solution indicates which part of the uniform theory of diffraction (UTD) solution for the wedge-diffracted field should be taken to describe its single-face component.     

The Excitation of a Dielectric Rod by a Cylindrical Waveguide

This paper is a theoretical analysis of the excitation of the lowest circular symmetric TM surface wave along an infinite circular dielectric rod by a metallic cylindrical waveguide coaxial with the rod. The asymptotic expressions for all the fields are obtained by means of the Wiener-Hopf method. The expressions for the total average power transmitted to the surface wave, the total average power reflected, and the total power radiated, per unit incident power, are derived and computed for epsilon=2.49 for various radii of the dielectric rod.     

准二维强耦合激子能量的温度依赖性

采用线性组合算符法和LLP变分法研究了晶格热振动和极化子效应对量子阱中激子与界面光学(IO)声子强耦合又与体纵光学(LO)声子弱、中耦合体系的基态和激发态的影响,推导出作为量子阱宽和温度函数的激子基态能量的移动和第一内部激发态能量的移动的表达式,以AgCl/AgBr/AgCl量子阱为例进行了数值计算.结果表明,由激子IO声子强耦合所产生的激子基态能量移动和第一内部激发态能量移动随温度的升高而增大,而由激子-LO声子弱、中耦合所产生的激子基态能量移动和第一内部激发态能量移动随温度的升高而减小.     

间接跃迁本征半导体的非线性极化率(英文)

<正>This Paper studies the optieal nonlinear problems of the semieondue-tors beeause of indireet transition。     

The Application of the Discrete Mode Matching Method to Noncircular Dielectric Waveguides

This letter presents an extension of the discrete mode matching method to the analysis of dielectric waveguides with noncircular cross sections. The problem is analyzed in cylindrical coordinates expanding the fields in terms of Bessel functions. Matching of the fields tangential to the interfaces between different dielectric layers is ensured by applying the proper boundary conditions. The mathematical formulation is given in this letter, followed by its application to compute the propagation constants in elliptical dielectric waveguides.     

Tuning the Polarizability in Donor Polymers with a Thiophenesaccharin Unit for Organic Photovoltaic Applications

This paper describes the synthesis of low bandgap copolymers incorporating an artificial sweetener derivative, N‐alkyl, 3‐oxothieno[3,4‐d]isothiazole 1,1‐dioxide (TID). This new TID unit is identical to the well‐known thieno[3,4‐c]pyrrole‐4,6‐dione (TPD) unit except that one carbonyl has been replaced by a sulfonyl group. Semi‐empirical calculations on the local dipole moment change between ground and excited states (Δμ_ge) in the repeating units of the new polymer indicate that the replacement of the carbonyl by a sulfonyl group leads to larger Δμ_ge values. The resulting polymers exhibit a diminished power‐conversion efficiency (PCE) compared to a bulk heterojunction (BHJ) solar cells with PC₇₁BM as an acceptor, which extends the correlation between PCE and Δμ_ge of single repeating units in p‐type polymers to a new regime. Detailed studies show that the strongly electron‐withdrawing sulfonyl group is detrimental to charge separation in alternating copolymers containing a TID unit.