基于薄膜电极溶胶修饰的染料敏化太阳电池光电特性研究

染料敏化太阳电池(DSC)中的纳米薄膜电极 是决定太阳电池光电转换性能的重要组成部分. 为改善薄膜电极特性, 采用了不同浓度的TiO₂溶胶对DSC光阳极导电玻 璃和纳米TiO₂多孔薄膜进行不同方式的界面处理. 利用X射线衍射方法对制备得到的多孔薄膜以及溶胶经高温处理 后致密层中纳米TiO₂颗粒的尺寸及晶型进行了测试. 采用高分辨透射电子显微镜和场发射扫描电子 显微镜观察了纳米颗粒及薄膜微结构形貌. 采用强度调制光电流谱/光电压谱分析了TiO₂溶 胶的不同处理方式对电子传输和复合的影响. 在100 mW· cm^-2光强以及暗环境下分别测试了DSC的伏安输出性能以及暗电流. 结果表明, 不同浓度和处理方式均能较好地抑制暗电流. 溶胶处理后光生电子寿命τ_n延长, 电子传输平均时间τ_d相应缩短. 采用浓度为0.10 mol·L^-1的 溶胶对导电玻璃和多孔膜同时处理, DSC的宏观输出特性最佳, 短路电流密度J_sc提高了10.9%, 光电转换效率η提高了11.9%.     

基于超导量子比特的电磁感应透明研究进展

超导量子计算是目前被认为最有希望实现量子计算机的方案之一. 超导量子比特是超导量子计算的核心部件. 如何尽可能的增加超导量子比特的退相干时间, 大规模的集成超导量子比特已成为超导量子计算研究的主要方向. 超导量子比特作为宏观的人工原子, 有许多量子光学现象都能够在其中观测到. 利用超导量子比特实现电磁感应透明为研究超导量子比特的退相干机理提供了新手段, 为研究非线性光学、光存储、光的超慢速传输等量子光学效应开辟了新思路. 本文介绍了电磁感应透明的理论基础, 总结了目前针对超导量子比特的电磁感应透明研究进展, 对比了一般气体原子与超导量子比特的电磁感应透明区别, 并对超导量子比特实现电磁感应透明的潜在应用进行了总结和展望.     

冲击加载下Zr51Ti5Ni10Cu25Al9金属玻璃的塑性行为

进行了10—27 GPa应力范围内Zr₅₁Ti₅Ni₁₀Cu₂₅Al₉金属玻璃的平面冲击实验以研究其高压-高应变率加载下的塑性行为.由样品自由面粒子速度剖面的分析获得了冲击加载过程的轴向应力,并通过轴向应力与静水压线的比较获得剪应力.实验结果表明,尽管存在明显的松弛效应,但Zr基金属玻璃的Hugoniot弹性极限随着冲击应力的增加而增加.然而,塑性波阵面上的剪应力则显示先硬化而后软化现象,而且软化的幅度随冲击应力的增加而增加.冲击加载下Zr基金属玻璃的上述剪应力变化特征与分子动力学模拟结果比较一致,但与压剪实验结果和一维应力冲击实验结果明显不同.     

Dielectronic recombination and resonant transfer excitation processes for helium-like krypton

The relativistic configuration interaction method is employed to calculate the dielectronic recombination(DR) cross sections of helium-like krypton via the 1s2lnl ’(n = 2,3,...,15) resonances.Then,the resonant transfer excitation(RTE) processes of Kr 34+ colliding with H,He,H 2,and CH x(x = 0-4) targets are investigated under the impulse approximation.The needed Compton profiles of targets are obtained from the Hartree-Fock wave functions.The RTE cross sections are strongly dependent on DR resonant energies and strengths,and the electron momentum distributions of the target.For H 2 and H targets,the ratio of their RTE cross sections changes from 1.85 for the 1s2l2l ’ to 1.88 for other resonances,which demonstrates the weak molecular effects on the Compton profiles of H 2.For CH x(x = 0-4) targets,the main contribution to the RTE cross section comes from the carbon atom since carbon carries 6 electrons;as the number of hydrogen increases in CH x,the RTE cross section almost increases by the same value,displaying the strong separate atom character for the hydrogen.However,further comparison of the individual orbital contributions of C(2p,2s,1s) and CH 4(1t 2,2a 1,1a 1) to the RTE cross sections shows that the molecular effects induce differences of about 25.1%,19.9%,and 0.2% between 2p-1t 2,2s-2a 1,and 1s-1a 1 orbitals,respectively.     

Intersubband transitions in Al0.82In0.18N/GaN single quantum well

The influence of the width of a lattice-matched Al_0.82In_0.18N/GaN single quantum well (SQW) on the absorption coefficients and wavelength of the intersubband transition (ISBT) has been investigated by solving the Schrödinger and Poisson equations self-consistently. The wavelength of 1—2 ISBT increases with L, the thickness of the single quantum well, ranging from 2.88 μm to 3.59 μm. The absorption coefficients of 1—2 ISBT increase with L at first and then decrease with L, with a maximum when L is equal to 2.6 nm. The wavelength of 1—3 ISBT decreases with L at first and then increases with L, with a minimum when L is equal to 4 nm, ranging from approximately 2.03 μm to near 2.11 μm. The absorption coefficients of 1—3 ISBT decrease with L. The results indicate that mid-infrared can be realized by the Al_0.82In_0.18N/GaN SQW. In addition, the wavelength and absorption coefficients of ISBT can be adjusted by changing the width of the SQW.     

Development of a 64 channel ultrasonic high frequency linear array imaging system

In order to improve the lateral resolution and extend the field of view of a previously reported 48 element 30 MHz ultrasound linear array and 16-channel digital imaging system, the development of a 256 element 30 MHz linear array and an ultrasound imaging system with increased channel count has been undertaken. This paper reports the design and testing of a 64 channel digital imaging system which consists of an analog front-end pulser/receiver, 64 channels of Time-Gain Compensation (TGC), 64 channels of high-speed digitizer as well as a beamformer. A Personal Computer (PC) is used as the user interface to display real-time images. This system is designed as a platform for the purpose of testing the performance of high frequency linear arrays that have been developed in house. Therefore conventional approaches were taken it its implementation. Flexibility and ease of use are of primary concern whereas consideration of cost-effectiveness and novelty in design are only secondary. Even so, there are many issues at higher frequencies but do not exist at lower frequencies need to be solved. The system provides 64 channels of excitation pulsers while receiving simultaneously at a 20–120 MHz sampling rate to 12-bits. The digitized data from all channels are first fed through Field Programmable Gate Arrays (FPGAs), and then stored in memories. These raw data are accessed by the beamforming processor to re-build the image or to be downloaded to the PC for further processing. The beamformer that applies delays to the echoes of each channel is implemented with the strategy that combines coarse (8.3 ns) and fine delays (2 ns). The coarse delays are integer multiples of the sampling clock rate and are achieved by controlling the write enable pin of the First-In-First-Out (FIFO) memory to obtain valid beamforming data. The fine delays are accomplished with interpolation filters. This system is capable of achieving a maximum frame rate of 50 frames per second. Wire phantom images acquired with this system show a spatial resolution of 146 μm (lateral) and 54 μm (axial). Images with excised rabbit and pig eyeball as well as mouse embryo were also acquired to demonstrate its imaging capability.     

Design and fabrication of Gires�CTournois interferometers for?Yb-doped photonic crystal fiber laser system

A Gires?CTournois interferometer (GTI) with large dispersion compensation was designed and fabricated according to the requirement of the Yb-doped photonic crystal fiber laser system. The designed GTI can provide an average group delay dispersion (GDD) of ?1500 fs² and a high reflectance (>99.7%) from 1030 to 1050 nm. The Ion-assisted Deposition (IAD) technique was utilized to manufacture the mirror. Good agreement between the measured and designed results both for reflectance and GDD was achieved. The reflectance during 1030?C1050 nm was above 99.5% and the GDD ripple was less than ±300 fs². The GTI was used both in the intracavity dispersion compensation and extracavity pulse compression for the Yb-doped photonic crystal fiber laser system. A mode-locked soliton pulse with a 506-fs duration was recorded. An extracavity pulse compression test showed that the GTI had identical pulse compression capability as the conventional grating pairs while the energy loss was obviously reduced. Our results demonstrated that the HDM, which was able to provide quite a large amount of negative dispersion (???8×10⁴ fs²), could be an ideal alternative to replace the dispersive compensating grating pairs for the dispersion compensation of the Yb-doped photonic crystal fiber laser system.     

Level structures in the 114 In nucleus

High-spin states in ¹¹⁴In were populated using the reaction ¹¹⁰Pd(⁷Li, 3n)¹¹⁴In at a beam energy of 26MeV. The level scheme of ¹¹⁴In consisting of six bands is established up to excitation energy ～ 5MeV and spin ～ 17 ? with the addition of 58 new transitions and their configurations are discussed. The intense positive-parity dipole cascade may be interpreted as shears band based on $ \pi$ [(g _9/2)^-1] ? $ \nu$ [(g _7/2/d _5/2)(h _11/2)²] configuration. The $ \Delta$ I = 2 bands based on proton excitation have been observed in ¹¹⁴In for the first time.     

Observation of ZnO nanoparticles outside pores of nano Zn4O(C8H4O4)3 metal-organic framework

It was recognized that ZnO can be formed during synthesizing nano Zn₄O(C₈H₄O₄)₃ metal-organic framework (nano MOF-5). Furthermore, it is generally accepted that the ZnO is dispersed inside the pores of MOF-5. However, herein, the measurements of X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) showed that the crystal particle sizes of ZnO in MOF-5 are in the range of 5-18 nm, which are larger than the pore size of MOF-5 (1.3 nm). This clearly demonstrates that those ZnO nanoparticles are located outside the pores of MOF-5.     

Ballistic phonon transport through a Fibonacci array of acoustic nanocavities in a narrow constriction

We investigate the ballistic phonon transport through a Fibonacci array of acoustic nanocavities in a narrow constriction of a semiconductor nanowire at low temperatures. It is found that the transmission spectrum of such a system consists of quasiband gaps and narrow resonances caused by the coupling of phonon waves. Both phonon transmission and thermal conductance exhibit the similarity due to the Fibonacci sequence structure. The similarity is sensitive to the number n and parameters of nanocavities. The results are compared with those in a periodic acoustic nanocavities.