The quantum spectra analysis of the circular billiards in wells

We use a recently defined quantum spectral function and apply the method of closed-orbit theory to the 2D circular billiard system. The quantum spectra contain rich information of all classical orbits connecting two arbitrary points in the well. We study the correspondence between quantum spectra and classical orbits in the circular, 1/2 circular and 1/4 circular wells using the analytic and numerical methods. We find that the peak positions in the Fourier- transformed quantum spectra match accurately with the lengths of the classical orbits. These examples show evidently that semi-classlcal method provides a bridge between quantum and classical mechanics.

Statistical Behaviors of Quantum Spectra in Superheavy Nuclei

From the point of view of the interplay between order and chaos, the most regular single-particle motion of neutrons has been found in the superheavy system with Z ＝ 120 and N ＝ 184 based on the Skyrme-Hartree-Fock model and in the system with Z ＝ 120 and N ＝ 172 based on the relativistic mean-field model. It has been shown that the statistical analysis of spectra can give valuable information about the stability of suprheavy systems. In addition it may yield deep insight into the single-particle motion in the mean field formed by the superheavy system.

Polar Mixing Optical Phonon Spectra in Wurtzite GaN Cylindrical Quantum Dots: Quantum Size and Dielectric Effects

混合 quasi-zero-dimensional (QoD ) 的声子模式的 interface-optical-propagating (IO-PR ) wurtzite 圆柱的量点(QD ) 结构被雇用宏观的绝缘的连续统模特儿导出并且学习。混合模式的 IO-PR 的分析声子状态被给。有混合声子模式的 IO-PR 的二种类型，这被发现，即混合在 QoD wurtzite QD 存在的模式的 -IO/z-PR 混合模式和 z-IO/-PR。并且各， IO-PR 混合模式也有对称并且 antisymmetrical 表格。经由领域量子化的一个标准过程， Fr ? 电子的 hlich Hamiltonians --(IO-PR ) 混合声子相互作用被获得。wurtzite 上的数字计算轧了圆柱的 QD 被执行。结果表明光线方向的尺寸和轴方向的尺寸以及绝缘的矩阵在混合声子模式的 IO-PR 的散频率上有大影响。这些声子模式的散曲线的限制特征深入地被讨论。减少的声子模式“ wurtzite 量的行为限制了系统在结构显然被观察了。而且，在 wurtzite Q2D QW 和 Q1D QWR 系统在 wurtzite QoD QD 混合声子模式到 IO 模式和 PR 模式的 IO-PR 的堕落行为物理和数学的观点从两个深深地被分析。

Evaluation of polarization field in InGaN/GaN multiple quantum well structures by using electroluminescence spectra shift

In order to investigate the inherent polarization intensity in InGaN/GaN multiple quantum well(MQW) structures,the electroluminescence(EL) spectra of three samples with different GaN barrier thicknesses of 21.3 nm, 11.4 nm, and 6.5 nm are experimentally studied. All of the EL spectra present a similar blue-shift under the low-level current injection,and then turns to a red-shift tendency when the current increases to a specific value, which is defined as the turning point.The value of this turning point differs from one another for the three InGaN/GaN MQW samples. Sample A, which has the GaN barrier thickness of 21.3 nm, shows the highest current injection level at the turning point as well as the largest value of blue-shift. It indicates that sample A has the maximum intensity of the polarization field. The red-shift of the EL spectra results from the vertical electron leakage in InGaN/GaN MQWs and the corresponding self-heating effect under the high-level current injection. As a result, it is an effective approach to evaluate the polarization field in the InGaN/GaN MQW structures by using the injection current level at the turning point and the blue-shift of the EL spectra profiles.

Evaluation of electron-electron interactions in coupled quantum dots by using far-infrared spectra

We have studied the far-infrared spectra of two-electron vertically coupled quantum dots in an axial magnetic field by exact diagonalization. The calculated results show an obvious difference in role between the interactions for spin S = 1 and for spin S = O. The results support the possibility to evaluate the interactions by far-infrared spectroscopy in vertically coupled quantum dots.

QUANTUM CHEMICAL CALCULATIONS ON THE ELECTRONIC STRUCTURE AND SPECTRA OF[Mo_3O_4-nSn]^(4+)(n=O-4)CLUSTER CATIONS

The electronic structure and spectra of [Mo3O4-nSn]^(4+)(n=0-4) cations were calculated by means of INDO/CI quantum chemistry method to account for the experimental data of their spectra in water solutions.

The Hydrogen Atom Fractal Spectra, the Missing Dark Energy of the Cosmos and Their Hardy Quantum Entanglement

In this letter, I outline the intimate connection between the fractal spectra of the exact solution of the hydrogen atom and the issue of the missing dark energy of the cosmos. A proposal for a dark energy reactor harnessing the dark energy of the Schrodinger wave via a quantum wave nondemolition measurement is also presented.

A Uqp (ul, 1) model for vibrational molecular spectra

A Uqp （ul,1） model is presented for describing vibrational spectra of diatomic molecules. The model is tested on the vibrational spectra in the X1∑8+ state of H2 obtainel thrugh the Rydberg-Klein-Ress （RKR） method.

Stable Temperature Characteristics of InAs/GaAs Quantum Dots at Long Wavelength Emission

The time-resolved photoluminescence and steady photoluminescence (TRPL and PL) spectra on self-assembled InAs/GaAs quantum dots (QDs) are investigated. By depositing GaAs/InAs short period superlattices (SLs), 1.48μm emission is obtained at room temperature. Temperature dependent PL measurements show that the PL intensity of the emission is very steady. It decays only to half as the temperature increases from 15K to room temperature, while at the same time, the intensity of the other emission decreases by a factor of 5 orders of magnitude. These two emissions are attributed to large-size QDs and short period superlattices (SLs), respectively. Large-size QDs are easier to capture and confine carriers, which benefits the lifetime of PL, and therefore makes the emission intensity insensitive to the temperature.

Optical Characteristics of InAs Quantum Dots on GaAs Matrix by Using Various InGaAs Structures

The effcts of various InGaAs layers on the structural and optical properties of InAs self-assembled quantum dots（ QDs ） grown by molecular-beam epitaxy （MBE） were investigated. The emission wavelength of 1317 nm was obtained by embedding InAs QDs in InGaAs / GaAs quantum well. The temperature-dependent and time-resolved photoluminescence （ TDPL and TRPL ） were used to study the dynomic characteristics of carriers. InGaAs cap layer may improve the quality of quantum dots for the strain relaxation around QDs, which results in a stronger PL inteasity and an increase of PL peak lifetime up to 170 K. We found that InGaAs buffer layer may reduce the PL peak lifetime of InAs QDs, which is due to the buffer layer accelerating the carrier migration. The results also show that InGaAs cap layer can increase the temperature point when the thermal reemission and nonradiative recombination contribute significantly to the carrier dynamics.

Synthesis, Crystal Structure,Characterization and Quantum Chemical Studies on 1N-Acetyl-3-(2,4-dichloro-5-fluoro- phenyl)-5-(p-methyl-phenyl)-2-pyrazoline

1N-Acetyl-3-（2,4-dichloro-5-fluoro-phenyl）-5-（p-methyl-phenyl）-2-pyrazoline has been synthesized and characterized by elemental analysis, IR, UV-Vis and X-ray single-crystal diffraction. Ab intio calculations have been carded out for the compound by using both B3LYP and HF methods at the 6-31G^＊ basis set. The calculated results show that the predicted geometry can well reproduce the structural parameters. The electronic absorption spectra calculated by B3LYP/6-31G^＊ method are approximate to the experiments and the Natural Bond Orbital （NBO） analyses suggest that the above electronic transitions are mainly assigned to n→π^＊ and π→π^＊ transitions. CIS-HF/6-31G^＊ method is not suitable to predict the electronic spectra for the title compound. The calculation of the second order optical nonlinearity was carded out, giving the value of molecular hyperpolarizability equal to 2.194^＋ 10^-30 esu. On the basis of vibrational analyses, the thermodynamic properties of the compound at different temperature have been calculated, revealing the correlation between C p, m^0, S m^0, H m^0 and temperature.

Proper In deposition amount for on-demand epitaxy of InAs/GaAs single quantum dots

The test-QD in-situ annealing method could surmount the critical nucleation condition of InAs/GaAs single quantum dots（SQDs） to raise the growth repeatability.Here,through many growth tests on rotating substrates,we develop a proper In deposition amount（θ） for SQD growth,according to the measured critical θ for test QD nucleation（θ;）.The proper ratio θ/θ;,with a large tolerance of the variation of the real substrate temperature(T;),is 0.964-0.971 at the edge and> 0.989 but < 0.996 in the center of a 1/4-piece semi-insulating wafer,and around 0.9709 but < 0.9714 in the center of a 1/4-piece N;wafer as shown in the evolution of QD size and density as θ/θ;varies.Bright SQDs with spectral lines at 905 nm-935 nm nucleate at the edge and correlate with individual 7 nm-8 nm-height QDs in atomic force microscopy,among dense 1 nm-5 nm-height small QDs with a strong spectral profile around 860 nm-880 nm.The higher T;in the center forms diluter,taller and uniform QDs,and very dilute SQDs for a proper θ/θ;:only one 7-nm-height SQD in25 μm;.On a 2-inch（1 inch = 2.54 cm） semi-insulating wafer,by using θ/θ;= 0.961,SQDs nucleate in a circle in 22%of the whole area.More SQDs will form in the broad high-T;region in the center by using a proper θ/θ;.

Crystal and Molecular Structure, and Spectral Characteristics of Sodium 3,5-Bis(Hydroxyimino)-1-Methyl-2,4,6-Trioxocyclohexanide

Sodium 3,5-bis(hydroxyimino)-1-methyl-2,4,6-trioxocyclohexanide C7H5N2NaO5 (I) has been isolated as the only product of the reaction of nitrosation of methylphloroglucinol. The structure of the titled compound has been determined from single crystal X-ray diffraction data. The hydrated C7H5N2NaO52.5H2O crystallizes in the monoclinic space group C2/c, with a(?) 16.408(3);b(?) 12.446(3);c(?) 13.716(3);(o) 126.34(3). The planar organic anion exists in a triketo-dihydroxyimino form with the C–O and C–N distances from 1.220(2) to 1.271(2)?? and from 1.292(2) to 1.293?? respectively. In the IR spectrum of I, the sharp absorption band occurred at 1681 cm-1 due to C=O stretching indicating the strong H-interactions. The correlations of theoretical (DFT-B3LYP/aug-cc-pVDZ) and experimental UV-vis absorption spectra in neutral and alkaline ethanolic solutions showed the existence of hydroxyimino-nitroso tautomerism while ionization of I.

4.3 THz quantum-well photodetectors with high detection sensitivity

We demonstrate a high performance GaAs/AlGaAs-based quantum-well photodetector （QWP） device with a peak response frequency of 4.3 THz. The negative differential resistance （NDR） phenomenon is found in the dark currentvoltage （I-V） curve in the current sweeping measurement mode, from which the breakdown voltage is determined. The photocurrent spectra and blackbody current responsivities at different voltages are measured. Based on the experimental data, the peak responsivity of 0.3 A/W （at 0.15 V, 8 K） is derived, and the detection sensitivity is higher than 10u Jones, which is in the similar level as that of the commercialized liquid-helium-cooled silicon bolometers. We attribute the high detection performance of the device to the small ohmic contact resistance of -2Ω and the big breakdown bias.

Blue-Red Tuning Emission of ZnO: Europium Quantum Dots with Different Excitation Wavelengths

Optoelectronic applications require the development of new fluorescent and efficient luminescent materials, free of toxicity, low in cost, and easy to produce. In this way the synthesis of zinc-oxide (ZnO) quantum dots (QDs) has recently received special attention due to their good optical, electrical and chemical properties with low production costs and blue light emission. In this work ZnO QDs were successfully doped with europium in order to obtain a tunable emission luminescence from blue emission of ZnO to red emission of europium as a function of wavelength excitation. Results show an efficient blue to red tuning when the excitation wavelength was changed from 317 nm to 395 nm, respectively. This opens the possibility of having new optical devices to produce different color emission using the same material.

多变量Si杂质诱导InGaAs/AlGaAs量子阱混杂研究

腔面光学灾变损伤是导致高功率量子阱半导体激光器阈值输出功率受限制的关键因素。通过量子阱混杂技术调整半导体激光器腔面局部区域处有源区材料的带隙宽度,形成对输出光透明的非吸收窗口,可提高激光器输出功率。本文基于InGaAs/AlGaAs高功率量子阱半导体激光器初级外延片,以外延Si单晶层作为扩散源,结合快速热退火方法开展了杂质诱导量子阱混杂研究。探索了介质层生长温度、介质层厚度、热处理温度、热处理时间等条件对混杂效果的影响。结果表明,50 nm的650℃低温外延Si介质层并结合875℃/90 s快速热退火处理可在保证光致发光谱的同时获得约57 nm的波长蓝移量。能谱测试发现,Si杂质扩散到初级外延片上的波导层是导致量子阱混杂效果显著的关键。

MgO-TiO_(2)二元系熔体结构的原位超高温拉曼光谱研究

利用激光加热超高温气动悬浮熔体和皮秒拉曼光谱测试技术耦合,有效抑制超高温黑体辐射对拉曼光谱的影响,获得了高信噪比的二元镁钛酸盐系列熔体拉曼光谱。定量分析了熔体中团簇结构的分布及其随组分浓度的变化规律。定量分析表明:MgO-TiO_(2)二元系熔体中存在H_(0)、Q_(0)、Q_(1)、Q_(2)和Q_(3)微结构单元,且随TiO_(2)浓度的增加,熔体中四配位TiO_(4)四面体逐渐向六配位TiO_(6)八面体转变。

激光烧蚀制备石墨烯量子点的多发光带的荧光光谱研究

石墨烯量子点作为二维范德瓦尔斯晶体量子点的典型代表,具有一系列的优异性质和光明的应用前景[1]。特别是石墨烯量子点优异的发光特性,使其在细胞成像、荧光传感等领域表现出巨大的应用潜力[2-3]。然而,对石墨烯量子点发光机制的研究尚不清晰,这大大限制了石墨烯量子点发光的应用。其中一个重要原因在于,发光机制的实验和理论研究需要纯净的石墨烯量子点样品,以突显石墨烯量子点本身的发光。但常用的化学制备方式,由于需要浓酸、强碱、强氧化剂、高温或高压等条件,使得制备的石墨烯量子点常含有杂质。而杂质的存在会使发光机制研究中涉及到的因素变得复杂,部分杂质会使量子点发光减弱甚至淬灭。虽然传统的制备石墨烯量子点的方式都适合其相应的应用目标,但作为研究石墨烯量子点发光机制的目标还远远不够,因此就需要寻找制备高纯度的量子点的方法,特别是物理制备方法,以避免化学反应,并研究石墨烯量子点的荧光光谱。

三种2-苯乙烯基苯并噻唑类化合物荧光性能的量子化学研究

采用量子化学半经验方法RHF/AM1对 3种有较高杀霉活性的 2 苯乙烯基苯并噻唑类化合物的电致发光性质进行了理论研究 ,对探索新型有机发光材料以及设计具有特定光电转换功能材料的分子提供了一种新的研究方法。对各化合物进行的构型优化表明 ,分子具有一定的平面结构 ,且具有较大的离域π键。对优化后的构型进行振动分析 ,其最小振动频率分别为 1 3 5 0 ,9 66,7 5 3cm-1,均未出现虚频率。 4种化合物的HOMO和LUMO之间的能量差ΔE分别为 7 83 8,7 70 6,7 2 88eV ,ΔE较小 ,离域电子容易激发。在此基础上用RHF/CIS方法分别计算了它们的荧光光谱 ,选用 1 1 5 3个组态进行计算 ,所得结果与实验值基本符合。

三种氨基酸荧光光谱的量子化学研究

氨基酸荧光光谱的量子化学计算为氨基酸荧光分析方法的设计与选择提供了一定的理论依据。本文采用量子化学半经验方法AM1对三种氨基酸的荧光光谱进行了理论研究。对三种化合物的结构进行优化后 ,从其结构参数可知分子具有刚性平面结构 ,具有大的离域π键。并对优化后的构型作振动分析 ,均未出现虚频率 ,证明该结构是稳定构型。在此基础上 ,采用单激发态组态相互作用 (CIS)方法计算其荧光激发波长及强度 ,并给出了三种化合物荧光光谱的波长与CIS组态数之间的关系。所得计算结果与实验值基本吻合。