Preparation, structures and photoluminescent enhancement effect of PbWO4–TiO2 composite nanofilms

A novel route for preparing PbWO₄–TiO₂ nanofilms on a glass substrate is firstly proposed. The collodion is used as a dispersant and film-forming agent. The nanofilms are characterized through SEM, XRD, TG/DTA, PL and IR, respectively. The results of XRD indicate PbWO₄ particles with tetragonal scheelite structure and TiO₂ particles with Anatase phase, and SEM shows they are well dispersed in the substrate. Compared with nanoparticles, when TiO₂ nanoparticles are added in 5% ratio, the PL intensities at 395 nm of PbWO₄ nanofilms are enhanced obviously. IR spectrum reveals a large absorption band between 750 and 870 cm⁻¹, which is the W–O stretching vibration in WO₄ tetrahedron.     

NOVEL FORMATION AND DECAY MECHANISMS OF NANOSTRUCTURES ON THE SURFACE

For decades the research on thin-film growth has attracted considerable attention as these kinds of materials have the potential for a new generation of device application. It is known that the nuclei at the initial stage of the islands are more stable than others and certain atoms are inert while others are active. In this paper, by using kinetic Monte Carlo simulations, we will show that, when a surfactant layer is used to mediate the growth, a counter-intuitive fractal-to-compact island shape transition can be induced by increasing deposition flux or decreasing growth temperature. Specifically, we introduce a reaction-limited aggregation (RLA) theory, where the physical process controlling the island shape transition is the shielding effect of adatoms stuck to the stable islands on the incoming adatoms. Moreover, the origin of a transition from triangular to hexagonal and then to inverted triangular as well as the decay characteristics of three-dimensional islands on the surface and relations of our unique predictions with recent experiments will be discussed. Furthermore, we will present a novel idea to make use of the condensation energy of adatoms to control the island evolution along a special direction.     

ELDRS and dose-rate dependence of vertical NPN transistor

The enhanced low-dose-rate sensitivity (ELDRS) and dose-rate dependence of vertical NPN transistors are investigated in this article.The results show that the vertical NPN transistors exhibit more degradation at low dose rate,and that this degradation is attributed to the increase on base current.The oxide trapped positive charge near the SiO2-Si interface and interface traps at the interface can contribute to the increase on base current and the two-stage hydrogen mechanism associated with space charge effect can well explain the experimental results.     

CsI:Tl晶体对高能X光照射量的响应关系研究

在X光探伤系统中使用效率较高的CsI：Tl晶体作为X光转换体。CsI：Tl晶体对X光的响应关系是精密图像处理、定量测量所需的一项重要参量。理论上已经推导了CsI：Tl晶体对X光的响应呈现线性关系,并针对性地设计了在^60Co放射源上的定量测量实验,所获数据不仅充分证明了理论推导的正确性,还证明了相应系统的这种线性关系的线性度非常好。     

Improvement of amine-modification with piperazine for the adsorption of CO2

Both selectivity and capacity of CO₂ adsorption were considerably increased when PZ (piperazine) was added in MDEA (methyldiethylamine) that used to modify the surface of silica gels. The adsorbent saturated with CO₂ was regenerated at ambient temperature through nitrogen purge. A set of PSA (pressure swing adsorption) operation with 200 cycles was carried out and applicability of the modified adsorbent was thus illustrated. The CO₂ content in the column-top stream decreased from 13% to below 0.05% at steady state.     

交叉分子束方法研究H+CH4和H+CD4反应:CH3/CD3的振动激发态产物通道

We study the H+CH₄/CD₄→H₂/HD+CH₃/CD₃ reactions using the time sliced velocity map ion imaging technique. Ion images of the CH₃/CD₃ products were measured by the (2+1) resonance enhanced multi-photon ionization (REMPI) detection method. Besides the CH₃/CD₃ products in the ground state, ion images of the vibrationally excited CH₃/CD₃ products were also observed at two collision energies of 0.72 and 1.06 eV. It is shown that the angular distribution of the products CH₃/CD₃ in vibrationally excited states gradually vary from backward scattering to sideways scattering as the collision energy increases. Compared to the CH₃/CD₃ products in the ground state, the CH₃/CD₃ products in vibrationally excited states tend to be more sideways scattered, indicating that larger impact parameters play a more important role in the vibrationally excited product channels.     

关于量子体系的高效相干能量转移的最优初始化的研究

For an energy transfer network, the irreversible depletion of excited electron energy occurs through either an efficient flow into an outer energy sink or an inefficient decay. With a small decay rate, the energy transfer efficiency is quantitatively reflected by the average life time of excitation energy before being trapped in the sink where the decay process is omitted. In the weak dissipation regime, the trapping time is analyzed within the exciton population subspace based on the secular Redfield equation. The requirement of the noise-enhanced energy transfer is obtained, where the trapping time follows an exact or approximate 1/Γ-scaling of the dissipation strength Γ. On the opposite side, optimal initial system states are conceptually constructed to suppress the 1/Γ-scaling of the trapping time and maximize the coherent transfer efficiency. Our theory is numerically testified in four models, including a biased two-site system, a symmetric three-site branching system, a homogeneous onedimensional chain, and an 8-chromophore FMO protein complex.     

车载空调器设计平台研究与开发

针对车载空调器设计手工计算繁琐、设计周期长等诸多不便利特点,研制开发了基于VB和SOLIDEDGE软件的车载空调器设计平台。该平台不仅具有车载空调器整机开发、机组设备单独设计或选型以及换热器参数化设计的功能,还兼容了家用空调器设计开发的能力。平台运行平稳,结果直观可靠。     

多重分形谱及其在材料研究中的应用

详细讨论了多重分形谱中各参量的物理意义,拽出随机多重分形谱中出现异常区的原因。提出了一种舒去少量异常小的分布概率的方法,局部消除了异常区,最后介绍了一些多重分形谱在材料研究中的应用。     

纳米碳管的电化学贮锂性能

用透射电镜、高分辨透射电镜、X射线衍射和拉曼光谱表征了用催化热解法制备的纳米碳管的结构,研究了纳米碳管的电化学嵌脱锂性能。以纳米级铁粉为催化剂热解乙炔气得到的纳米碳管石墨化程度较低,结构中存在褶皱的石墨层、乱层石墨和微孔等缺陷,具有国交高的贮锂容量,初始容量为640mAh/g,但循环稳定性较差。而以纳米级氧化铁粉为催化剂热解乙烯得到的纳米碳管结构比较规则,循环稳定性较好,但贮锂容量较低,初始容量为282mAh/g。讨论了纳米碳管的结构对其温度特性和不同电流密度下的充放电容易的影响。