探针尖带金属微粒的光子扫描隧道显微镜成像数值模拟

引入了色散介质的时域有限差分法散射场方程,并针对光子扫描隧道显微镜的带金属尖光纤扫描成像问题进行三维的数值模拟。在考虑了光纤和样品相互作用的情况下,采用等效入射波法设置入射波,探针扫描模式为等高扫描模式,从成像分辨力和灵敏度的角度,比较了不同入射角、不同的光纤一样品间距,不同金属类型,及不同金属尖大小的成像情况。数值模拟结果显示,带金属颗粒光纤探针尖的光子扫描隧道显微镜在成像分辨力和灵敏度上有显著的改进,而带不同类型金属颗粒情况下对分辨力影响不大,灵敏度是银最好。     

可聚合型溶致液晶单体3,4,5-三(11-十一烷氧丙烯酰氧基)苯甲酸钠的自组装及紫外光固化性能

以3,4,5-三羟基苯甲酸为原料,依次经过酯化、醚化、酰氯化和钠盐化四步反应合成一种可聚合型溶致液晶单体3,4,5-三(11-十一烷氧丙烯酰氧基)苯甲酸钠,并对其结构进行了傅里叶变换红外与1H核磁表征. 在室温下研究了该单体在水中的自组装行为,组装体结构通过偏光显微镜与X射线衍射仪进行表征. 研究表明,单体与水比例为80:20时可自组装为层状(La)相,92:8时组装为反六方(H_II)相,这与临界堆积参数的理论计算相吻合,表明单体浓度是影响组装体结构的重要因素. 在组装的基础上研究了含不同光引发剂的溶致液晶体系的双键转化率及固化后组装体结构的保留. 经实时红外表征及溶胶-凝胶法的验证发现在光强为30 mW/cm²的365 nm下曝光30 min,含引发剂Darocur2959的溶致液晶体系双键转化率可达78%. 聚合之后La相与H_II相的纳米结构都得到了保留.     

离子速度成像技术研究2-溴戊烷的光解离动力学

运用离子速度成像技术研究了2-溴戊烷分子在～234 nm处的光解离动力学. 通过分析光解产物Br(²P_3/2)(简称Br)和Br(²P_1/2) (简称Br*)的速度影像,分别得到其速度分布和角度分布. Br和Br*的速度分布可以用两个高斯分布拟合,分别对应于2-溴戊烷在～234 nm处两个独立的光解离反应通道. 高能的高斯分量对应于C-Br伸缩振动模式的直接解离,低能的高斯分量对应于弯曲振动和C-Br伸缩振动耦合所导致的解离. 确定出光解离产物Br的相对量子产率为0.892,结合Br和Br*碎片的各项异性参数和溴原子的相对量子产率,讨论了³Q₀、³Q₁和¹Q₁激发态分别对产物Br和Br*的贡献. 通过对比溴代戊烷4种同分异构体光解离过程的差异,讨论了分子烷基分支化对光解机理的影响.     

An improved least square channel estimation algorithm for coherent optical OFDM system

This paper presents an improved processing added to conventional least square (LS) channel estimation to modify its performance for coherent optical orthogonal frequency division multiplexing (CO-OFDM) system. By testing selected limitation factors of the existing algorithms, the influence of our improved algorithm to the performance of CO-OFDM system were studied and compared with other published algorithms. The simulation results of the study demonstrated that the proposed approaches achieved better channel estimation performance and are considered as a more appropriate alternative for CO-OFDM system with the tradeoff between complexity and performance.     

Strong perpendicular magnetic anisotropy in Co2FeAl0.5Si0.5 film sandwiched by MgO layers

Co2FeAl0.5Si0.5 (CFAS)-based multilayers sandwiched by MgO layers have been deposited and annealed at different temperatures. Perpendicular magnetic anisotropy (PMA) with the magnetic anisotropy energy density Ku ≈2.5×106 erg/cm3 (1 erg = 10-7 J) and the coercivity Hc = 363 Oe (1 Oe = 79.9775 A · m-1) has been achieved in the Si/SiO2/MgO (1.5 nm)/CFAS (2.5 nm)/MgO (0.8 nm)/Pt (5 nm) film annealed at 300 ℃. The strong PMA is mainly due to the top MgO layer. The structure can be used as top magnetic electrodes in half-metallic perpendicular magnetic tunnel junctions.     

服务于智能制造的智能检测技术探索与应用

为了促进工业4.0与“中国制造2025”战略在制造行业的实施,在智能制造体系中构建有效的控制层级与设备层级,促进车间状态数据与智能制造工艺流程的结合,本文提出了通过智能仪器与智能检测技术实现车间状态智能感知与工艺流程控制的方法,并探讨了智能仪器与智能检测技术在智能制造系统中新的应用模式,同时结合实际项目进行了数字化生产线改造与建设的创新实践,提出了满足智能制造要求的智能仪器与检测技术的发展方向。经项目实践验证,通过智能检测设备与智能仪器的应用,可有效促进智能制造系统中数据采集、智能感知的实现,并为整体工艺流程的智能决策提供有效的数据资源,是智能制造系统建立与完善的关键基础。     

Magnetic,electrical transport and electron spin resonance studies of ferromagnetic insulating manganites Nd0.85Na0.15MnO3

We have investigated the magnetic, electrical transport and electron spin resonance (ESR) properties of polycrystalline Nd_0.85Na_0.15MnO₃ prepared by sol–gel method. A ferromagnetic–paramagnetic (FM–PM) transition is observed around 110 K, which is not accompanied by a metal–insulator transition. The sample displays the complete PM state associated with the ESR spectra fitted by single Lorentzian line shape above 130 K. Below 130 K, ESR spectra become distorted and then linewidth increases rapidly, where short-range magnetic order develops and coexists with PM phase due to the inhomogeneous magnetic state. In addition, the large difference between the activation energies obtained from the resistivity and ESR parameters (peak-to-peak linewidth and line intensity) at the frame of adiabatic small polaron hopping model is pointed out for Nd_0.85Na_0.15MnO₃.     

态|Ψ(3)〉q中广义磁场的不等幂次高次振幅压缩

利用多模压缩态理论,研究了一种新型的三态叠加多模叠加态光场|Ψ⁽³⁾〉_q中广义磁场分量(即第一正交相位分量)的不等幂次高次振幅压缩特性.结果表明:态|Ψ⁽³⁾〉_q是一种典型的三态叠加多模非经典光场,其广义磁场分量在一定条件下可呈现出周期性变化的、偶数次的不等幂次高次振幅压缩效应.     

全固态多波长飞秒脉冲激光系统

利用棱镜对引进频谱空间啁啾来补偿飞秒脉冲激光二次谐波产生中的相位失配,提高了倍频效率建立了一套全固态、多波长(1065nm, 532nm,823.1nm, 402nm)飞秒脉冲激光系统自制的Nd:YVO4激光器输出532nm绿光激光,最高平均功率可达5.6W当用2.5W绿光激光泵浦时,从自制的钛宝石激光器及经BBO倍频可分别输出中心波长为823.1nm和402nm,平均功率300mW和73mW,谱宽32.3nm和5.1nm,脉宽22fs和33.3fs、重复率108MHz的近红外和蓝光激光整个系统具有结构紧凑、倍频效率高、运行稳定的特点.     

丙氨酸咪唑钐的三维荧光激发和发射光谱

测量了新制丙氨酸咪唑钐水溶液的三维荧光激发和发射光谱,分析了在不同波长激发光作用下的荧光特征,与配体咪唑、α-丙氨酸及氯化钐的荧光谱进行了比较,讨论了模型化合物上转换荧光中的双光子和多光子加合现象并发现在10^-2-10^-4 mol/L 浓度范围内荧光强度与溶液浓度呈正相关.