使用基于MAPPING哈密顿的对称准经典动力学方法和基于ML-MCTDH的量子动力学方法研究超快电子转移

Symmetrical quasi-classical (SQC) method based on mapping Hamiltonian is an efficient approach that is potentially useful to treat the nonadiabatic dynamics of very large systems. We try to evaluate the performance of this method in the ultrafast electron transfer processes involving a few of electronic states and a large number of vibrational modes. The multilayer multiconfigurational time-dependent Hartree (ML-MCTDH) method was used to get the accurate dynamical results for benchmark. Although the population dynamics in the longtime limit show differences in the ML-MCTDH and SQC calculations, the SQC method gives acceptable results.     

关于大学物理与中学物理衔接问题的教学研究探讨

中学物理与大学物理如何实现有效的衔接,是每位大学物理教师必须思考的普遍性问题。中学物理实行模块化教学,即分为必修模块和选修模块,大学物理相比较更具系统性,尤其是针对理工科学生的教学内容更为全面和深入。二者在教学内容、教学方式和思维方法上的差异导致大学生在学习过程中遇到很多困难,影响了大学物理的教学质量。作者通过分析学生由中学物理到大学物理过渡学习中出现的问题,提出必须要树立一种正确的学习理念,改变大学物理学习过程中的一些错误观念,从基础入手解决大学物理和中学物理课程之间的衔接。结合一些物理教学知识点,总结出实现中学物理到大学物理良好过渡的几点体会。     

Anisotropic electrical conductivity,phase transition and thermal hysteresis of a charge-transfer salt dibutylammonium bis-7,7,8,8-tetracyanoquinodimethane DBA（TCNQ）2

This paper reports that a charge-transfer salt dibutylammonium bis-7,7,8,8-tetraeyanoquinodimethane [DBA （TCNQ）2] has been prepared. The temperature dependences of the DC electrical conductivity of the DBA （TCNQ）2 single crystal measured along the crystallographic a, b, and c axes are reported. The crystal shows semicondueting behaviour and the room-temperature conductivities are highly anisotropic （σa = 3.63× 10^-4S/cm, σb = 2.84× 10^-6S/cm, and （σe = 1.82 × 10^-5S/cm）. Particularly, a sharp semiconductor to semiconductor transition has been observed around 270 K on the resistivity curves measured under cooling and heating. In addition, thermal hysteresis phenomena on conductivity and differential scanning calorimetry curves are also reported.     

导电聚合物微米/纳米结构的制备和性质

文章综述了导电聚合物微米／纳米结构(微米管、纳米管、纳米线和微米球等)近几年来所取得的研究进展．重点介绍了三种制备方法(模板合成、无模板法、电纺丝技术)和导电聚合物微米／纳米管的电学、力学、热学、磁学等性能．     

La2CuO4掺锌样品的低温电阻率与热导率研究

对La2CuO4掺锌样品在不同降温速率下(330K保温30min后,分别以6Kh和02Ks的速率冷却至42K)电阻率(42—330K)和热导率(80—300K)随温度的变化关系进行了研究.实验结果表明,在不同降温速率下,热导率和电阻率都受到很大影响.快速降温过程使得130K以上的热导率减小,而热导率最小值出现在130K,且与降温速率无关.而低温下的热导率不受降温速率变化的影响.样品在高温区(T高于125K)电阻率随降温速率的增大而增大,低温区电阻率的非线性行为可用变程跳跃行为来描述.所有样品的热导率和电阻率在反铁磁相变温度都没有出现反常,这与能带理论框架下预期的结果和Anderson电荷自旋分离理论发生了矛盾,对此进行了讨论,并用极化子理论进行了自洽解释. 关键词： La2CuO4 热导率 电阻率     

Reply to ＂Comment on ＇Electrical Conductivity and Current-Voltage Characteristics of Individual Conducting Polymer PEDOT Nanowires＇＂

Recently we reported electrical properties of an individual PEDOT nanowire .Ohlckers and Pipinys suggested that the temperature-behavior of I- V curves and resistance can be described in the framework of a phonon-assisted tunneling （PhAT） model. However, there are two points which need to be addressed. First, as shown in Figs. 1 and 2 of Ohlckers and Pipinys＇s Comment, obvious deviations have been observed between the experimental data and the fitting curves obtained from this model especially at low temperatures. Second, the PhAT model is based on the assumption that a source of charge carriers is the local electronic traps in the electrode-nanowire interface layer, the carriers enter the conduction band of the nanowire due to the PhAT through the barrier from these traps. This model has not considered the structure characteristics and conduction mechanism in polymer nanowires.     

Fabrication and formation mechanism of closed-loop fibers by electrospinning with a tip collector

Electrospun nanofibers with designed or controlled structures have drawn much attention. In this study, we report an interesting new closed-loop structure in individual cerium nitrate/polyvinyl alcohol(Ce(NO_3)_3/PVA) and Na Cl/PVA fibers,which are fabricated by electrospinning with a nail collector. The electrospinning parameters such as voltage and Ce(NO_3)_3(or Na Cl) concentration are examined for the formation of the closed-loop structure. The results suggest that the increase of the spinning voltage or addition of Ce(NO_3)_3(or Na Cl) is favorable for the formation of the closed-loop structure, and the increase of loop numbers and the decrease of loop size. Further analyses indicate that the formation mechanism of the closed-loop fibers can be predominantly attributed to the Coulomb repulsion in the charged jets.     

低压近场静电纺丝ZnO/PVDF复合微米纤维阵列的制备及压力传感性

利用低压近场静电纺丝技术制备了ZnO/PVDF(聚二偏氟乙烯)微米纤维平行阵列, 通过光学显微镜、扫描电子显微镜(SEM)和X射线能量色散光谱(EDS)对ZnO/PVDF微米纤维进行了表征. 该复合纤维的平均直径约为40 μm. EDS分析测试证明ZnO纳米颗粒已经掺杂进入了平行微米纤维中. 压电性能和电学性能测试结果表明, ZnO/PVDF微米纤维阵列的压电性能增强. 研究结果表明, 近场电纺丝ZnO/PVDF复合微米纤维阵列在压电型压力传感器和纳米发电机领域具有潜在的应用价值.     

Electrospun fluorescein/polymer composite nanofibers and their photoluminescent properties

Fluorescein/polyvinyl pyrrolidone (PVP) composite nanofibers with different fluorescein loadings (with a weight concentration of 0-5.0%) are fabricated via electrospinning. Morphologies, structures and photoluminescent (PL) properties of these straight, helical or wavelike fibers are characterized by scanning electron microscopy (SEM), fluorescence microscopy and a spectrophotometer. It is found that the maximum emission of the as-spun fluorescein/PVP fibers occurs at 510 nm. The PL intensity of the composite fiber increases with fluorescein concentration, then fluorescence quenching appears when the concentration reaches 1.67%. The mechanism of fluorescence quenching of fluorescein is discussed. In addition, the composite fibers exhibit a much stronger PL intensity than fluorescein/PVP bulk film owing to larger specific surface area, which makes them promising materials for biomedical applications such as probes and sensors.