交流电激发下的聚合物PPV单层薄膜发光器件的电致发光

交流电激发下的聚合物ＰＰＶ单层薄膜发光器件的电致发光＊张凤玲ａ，ｂ）杨志敏ａ）徐征ａ）黄宗浩ｃ）徐长远ａ）王永生ａ）徐叙王容ａ，ｂ）ａ）（北方交通大学光电子技术研究所，北京１０００４４）ｂ）（天津理工学院材料物理研究所，天津３００１９１）ｃ）（东北师...     

中专物理教学中的数学应用

物理学是研究物体运动及其规律的科学,许多物理学上的难题借助于数学推论得到了解决,对此,我谈谈自己在中专物理教学中的体会．１　极值问题常用求极值的数学方法：（１）重要不等式求极值：例如：ａ＋ｂ≥２ａｂ　（或　ａ２＋ｂ２≥２ａｂ）ａ＞０　ｂ＞０若ａ＋ｂ为一常量,则当且仅当ａ＝ｂ时,ａ＋ｂ有极大值．若ａ·ｂ为一常量,则当且仅当ａ＝ｂ时,ａ＋ｂ有极小值．（２）函数求极值：利用正、余弦函数、二次函数及某些特殊函数求极值．下面举例说明数学原理在求物理量极值中的应用．例１,点光源Ｓ到屏Ｍ的距离为Ｌ．焦距为ｆ的…     

掺杂Cu^2的ZnS纳米超微粒的荧光衰减

掺杂Ｃｕ２＋的ＺｎＳ纳米超微粒的荧光衰减＊李丹刘俊业孟继武窦凯ａ）许武ａ）孙聆东ｂ）李振鹏ｂ）（中国科学院长春物理研究所，长春１３００２１）ａ）（中国科学院激发态物理开放研究实验室，长春１３００２１）ｂ）（北京大学稀土材料化学及应用国家重点实验室，北...     

取向Kerr效应对液晶光控取向质量的影响

取向Ｋｅｒｒ效应对液晶光控取向质量的影响＊王淑梅ａ）梁兆颜闫石谢景力ｂ）田颜清ｂ）黄锡民ａ）（中国科学院激发态物理开放研究实验室，长春１３００２１）（中国科学院长春物理研究所，长春１３００２１）ｂ）（吉林大学化学系，长春１３００２３）关键词取向Ｋｅｒ...     

背景辐射与光子平衡态

背景辐射与光子平衡态张邦固（科学出版社北京１００７１７）ＢａｃｋｇｒｏｕｎｄＲａｄｉａｔｉｏｎａｎｄＰｈｏｔｏｎＥｑｕｉｌｉｂｒｉｕｍＳｔａｔｅＺｈａｎｇＢａｎｇｇｕ（ＳｃｉｅｎｃｅＰｒｅｓ,Ｂｅｉｊｉｎｇ１００７１７）ＡｂｓｔｒａｃｔＴｈｅＢａｃ...     

酶表面上的分形反应

本文报道了酶反应中的分形几何效应，用模拟方法研究了催化中的表面标度关系，假设“聚集态酶”有ＤＬＡ形态。每个酶分子作为逾集团中的一个分形体，则酶表面的活性点几率分布的ＤＡＳ（ａ，Ｍ）∝ｅｘｐ（－Ａ／ｌｎＭ）（ａ－ａ０（Ｍ），分雏为Ｄｘ＝Ｉｎ（ｂ－θ）（ｂ－θ＋１）／２＋２θ）／Ｉｎｂ。这里Ｍ是定域质量，ａ０（Ｍ）＝ＢＩｎＭ，Ａ，Ｂ是常数，ｂ是回转半径，θ是酶集团表面“空位”数，模拟知“中毒”时间Ｔｐ     

YBa2Cu3O7—δ掺Co样品的中子衍射研究

对磁性金属钴掺杂的ＹＢａ２（Ｃｕ１－ｙＣｏｙ）３Ｏ７－δ超导体进行了中子衍射研究。研究表明：钴原子择优占据Ｃｕ（１）晶位；随着钴一的增加，单胞中平均氧含量增加；晶胞的晶格常数α增大，ｂ减小，至ｙ＝０．０３８时，ａ＝ｂ，而ｃ是先增大再减小。     

聚糖联乙炔类脂轭合物与大肠杆菌的识别作用研究

聚糖联乙炔类脂轭合物与大肠杆菌的识别作用研究＊范翊ａ）李亚军ａ）ＷａｎｇＧＰｂ）张立功ａ）蒋大鹏ａ）于雅琴ｃ）黎明兰ｃ）ａ）（中国科学院长春物理研究所，长春１３００２１）ｂ）（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒｙ，ＷａｙｎｅＳｔａｔｅＵｎｉｖｅ...     

求解H=αa~+a+βb~+b+γ(a~+b~++ab)的波函数的简单方法

本文用能生成玻戈留玻夫变换的幺正变换的坐标表象简捷地给出哈密顿量Ｈ＝αａ~＋ａ＋βｂ~＋ｂ＋γ（ａ~＋ｂ~＋＋ａｂ）的波函数．     

玻戈留波夫变换在量子力学中关于求能量本征值的应用

如所周知，玻戈留波夫（Н．Н．Богпю　бов）变换已成功地用于超流、超导、声子－光子、声子－自旋波等一系列耦合问题［１］．解耦合的本质就是使体系的哈密顿量Ｈ对角化，以期得到能量的准确解．在量子力学中，我们经常遇到这一类问题．本文利用玻戈留波夫变换，给出非对角项为（ａ＋ｂ＋ａｂ）和（ａ＋ｂ＋ ｂ＋ａ）的哈密顿量的对角化方法，以期给正在学习量子力学的读者提供一种解决此类问题的方法．     

Resonant Brillouin scattering via free and bound excitons in CdSe

We report resonant Brillouin scattering results in CdSe. Enhancements in Brillouin scattering have been observed at both the I₂ bound exciton and the free exciton. As a result of the spatial dispersion of the exciton-polariton, the Brillouin frequencies vary with the polariton energy. From this variation of the Brillouin frequencies, we deduced the following parameters in CdSe: transverse exciton frequency =14713 cm^?1, splitting between longitudinal and transverse exciton frequencies = 4cm^?1 and exciton effective mass (perpendicular to the c-axis) =0.40 times free electron mass. The Brillouin linewidths were found to vary with polariton energies in qualitative agreement with the theory of Brenig, Zeyher and Birman.     

Coupled longitudinal and transverse stimulated Brillouin scattering in single-mode optical fibers

Due to their finite numerical aperture, both longitudinal and transverse stimulated Brillouin scattering can occur in single-mode fibers. We discuss the role of the fiber structure and propose a coherent model accounting for both effects. We show experimentally and numerically that, in some cases, the perturbative cladding Brillouin scattering (CBS) can severely affect the dynamics of SBS Brillouin fiber lasers. New dynamical regimes of long-fiber Brillouin ring lasers are presented, including stable trains of modulated pulses. Received 17 September 2001 / Received in final form 5 March 2002 Published online 28 June 2002     

Multicomponent Rayleigh scattering from guanidine hydrochloride solutions

We present results of Brillouin light scattering studies of lysozyme and guanidine hydrochloride solutions in the temperature range 290–350 K. The Brillouin spectra of 6 M guanidine hydrochloride have been found to contain an additional component in Rayleigh scattering that manifests itself as a broad quasi‐elastic scattering line centered at the unshifted frequency and described by a Lorentz function (i.e. a Debye relaxor with relaxation time τ₁ ~ 25 ps at room temperature). The temperature dependence of τ₁ is described by the Arrhenius law with activation energy E_a = 0.11 ± 0.01 eV and prefactor τ₀= 0.33 ± 0.03 ps. The Brillouin spectra of lysozyme denatured by 6 M guanidine hydrochloride exhibit a more complicated structure of the additional contribution into Rayleigh scattering, which is fitted best of all by a sum of two Lorentzians centered at the unshifted frequency (with relaxation times τ₁ ~ 19 ps and τ₂ ~ 180 ps at 339 K). Possible origins of the quasi‐elastic scattering are discussed. Copyright © 2012 John Wiley & Sons, Ltd.     

Guided acoustic wave Brillouin scattering in photonic crystal fibers

We experimentally investigate guided acoustic wave Brillouin scattering in several photonic crystal fibers by use of the so-called fiber loop mirror technique and show a completely different dynamics with respect to standard all-silica fibers. In addition to the suppression of most acoustic phonons, we show that forward Brillouin scattering in photonic crystal fibers is substantially enhanced only for the fundamental acoustic phonon because of efficient transverse acousto-optic field overlap. The results of our numerical simulations reveal that this high-frequency phonon is indeed trapped within the fiber core by the air-hole microstructure, in good agreement with experimental measurements.     

Stimulated Brillouin scattering in magnetized diffusive semiconductor plasmas

Using the hydrodynamical model and following the coupled mode approach, detailed analytical investigation of stimulated Brillouin scattering is performed in an electrostrictive semiconductor. The total induced current density including diffusion current density and the effective Brillouin susceptibility are obtained under off-resonant laser irradiation. The analysis deals with the qualitative behaviour of the Brillouin gain and transmitted intensity with respect to excess doping concentration and magnetic field. Efforts are directed towards optimizing the doping level and magnetic field to achieve maximum Brillouin gain at pump intensities far below the optical damage threshold level. It is found that by immersing a moderately doped semiconductor in a sufficiently strong magnetic field in transverse direction, one can achieve resonant enhancement of Brillouin gain provided the generated acoustic mode lies in the dispersionless regime.     

Stimulated Brillouin scattering of elliptical laser beam in collisionless plasma

This paper presents an investigation of self-focusing of elliptical laser beam in collisionless plasma and its effect on stimulated Brillouin scattering. The pump beam interacts with a pre-excited ion-acoustic wave leading to Brillouin back-scattered process. The transverse intensity gradient of a pump beam generates a ponderomotive force, which modifies the background plasma density profile in a direction transverse to pump beam axis. This modification in density effects the incident laser beam, ion-acoustic wave and back-scattered beam. Non-linear differential equations for the beam width parameters of pump laser beam, ion-acoustic wave and back-scattered beam are set up and solved numerically. It is observed from the analysis that the focusing of waves enhances the SBS back-reflectivity.     

The hyper-Raman spectrum of CsI

The hyper-Raman spectrum of CsI has been measured by the single channel method. Two lines corresponding to the transverse and longitudinal optic phonons at the centre of the Brillouin zone could be clearly observed. Nonlinear processes competing with hyper-Raman scattering are discussed.     

Longitudinal and transverse acoustic modes in α-AgI

Brillouin scattering experiments have been performed in the GHz frequency range in α-Agl to demonstrate the existence of both longitudinal and transverse acoustic phonons. From the measured frequency shifts the longitudinal velocity, the shear velocity and the elastic constants have been calculated.     

Soliton compression in Brillouin fiber lasers

Pulse propagation in optical fibers may electrostrictively excite acoustic waves as a result of cladding Brillouin scattering, transversally propagating with respect to the fiber axis in the fiber's cladding, and mechanical coating. We show, for the first time to our knowledge, experimentally and theoretically that these transverse resonances within finite frequency ranges may cooperatively couple with the acoustic longitudinal modes of a fiber resonator, giving rise to stable trains of either spread or compressed three-wave Brillouin solitons and propose a first stability map for the rich four-wave dissipative dynamics.     

Selective generation of longitudinal microsonic waves in n-GaAs

Longitudinal acoustic waves have been amplified from the thermal background in {111} oriented n-type GaAs and have been studied by observing Brillouin scattering. The generating technique uses a tuned voltage-square-wave, which eliminates the amplification of off-axis transverse modes.