利用吸附有双硫腙的微晶萘萃取色层富集--火焰原子吸收光谱法测定天然水中痕量铜

本文利用吸附有双硫腙的微晶萘作富集柱富集天然水中痕量铜，甲酰二甲胺洗脱，火焰原子吸收光谱法测定。对最佳吸附酸度，过柱流速，洗脱剂，共存离子干扰等进行了探讨。该方法的相对标准偏差为２．３％，加标回收率为９６％～１０３％。通过对国家标准水样及实际天然水样的分析测定，结果令人满意。     

中红外组合激光场调控宽带超连续谱的产生

本文对原子在波长为2000nm、脉宽为12.5fs的中红外驱动脉冲和脉宽为1.3fs的紫外控制脉冲叠加形成的组合场中产生的高次谐波进行了研究.通过组合场驱动氦原子得到了谱宽为230eV的超连续谱.利用组合场产生的谐波比单独利用中红外脉冲产生的谐波的强度高了3个量级.对超连续谱进行滤波并调节组合场中两束激光的延迟时间,可以直接产生100as的单个脉冲.我们发现超连续谱的宽度和位置几乎不会因为驱动场和控制场强度的变化而改变,这种性质有利于从实验上获得单个宽谱阿秒脉冲.     

周期量级激光脉冲驱动下非次序双电离的三维经典系综模拟

利用三维经典系综模型研究了周期量级激光脉冲驱动的氩原子非次序双电离,所得结果表明,Ar2+离子的纵向动量分布与载波包络相位有很强的依赖关系,随载波包络相位φ的增加,具有不对称双峰结构的离子纵向动量分布重心从负动量转移到正动量,并且φ每改变π时Ar2+离子的纵向动量呈现相反的分布.在重碰撞过程中核与电子之间的库仑势发生变化后,计算得到的Ar2+离子纵向动量分布随载波包络相位的变化与实验结果定量上一致.     

Large magnetoresistance in metamagnetic CoMnSi0.88Ge0.12 alloy

The magneto-transport properties are investigated in metamagnetic CoMnSi0.88Ge0.12 alloy.By applying a magnetic field or increasing temperature,a metamagnetic phase transition from antiferromagnetic to ferromagnetic is observed in this alloy.Around the metamagnetic phase transition,CoMnSi0.88Ge0.12 alloy exhibits a large and negative magnetoresistance effect(～32%) under a magnetic field of 20 kOe(1 Oe = 79.5775 A/m),which is ascribed to the spin-dependent scattering of conduction electrons.     

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用线圈电流控制非平衡磁场,用汤森放电击穿形成深度自触发放电,用磁阱捕获放电形成的二次电子和导致漂移电流,形成了高功率非平衡磁控溅射放电。采用偏压为-100V相对磁控靶放置的圆形平面电极收集饱和离子电流;在距离磁控靶14cm的位置由Langmuir探针测量浮置电位;示波器测量磁控靶的脉冲电压、电流、浮置电位和饱和离子电流信号。装置的放电脉冲功率达到0.9MW,脉冲频率最大值为40Hz左右,空间电荷限制条件是控制电子电流和离子电流的主要机制。     

用CCSD(T)方法计算基态SH和SD的光谱常数(英文)

利用CCSD(T)方法和系列相关一致基cc-pVXZ及aug-cc-pVXZ(X=D,T,Q,5)对SH和SD分子的基态平衡几何,谐振频率和离解能进行了优化计算.利用优选出的CCSD(T)/aug-cc-pV5Z方法对SH和SD的基态进行单点能计算,并将计算结果拟合成了Murrell-Sorbie函数.利用得到的解析势能函数,计算了SH和SD的其余3个光谱常数(ω_ex_e,α_e和B_c),结果表明:除SD的ω_ex_e值外,其余结果均与实验值符合得相当好,但计算得出的ω_ex_e值与推导出的值25.134 cm~(-1)符合得很好.     

S波段相对论速调管放大器锁相特性

对相对论速调管放大器（RKA）锁相特性进行了粒子模拟与实验研究。在2.5维粒子模拟中,研究了电子束电压波形特征对RKA锁相特性的影响,结果表明:电子束电压波形上冲对RKA锁相特性有正面影响,即能够减小相位差达到锁定状态的时间,幅度为20%的上冲导致大约23的相位差变化;波形顶降则对RKA锁相特性有负面影响,可使相位差过早地偏离稳定值,幅度为5%的顶降大约能引起50的相位差偏离;电压波形的上升时间对RKA相位锁定特性也有影响,但规律不明显。在三维粒子模拟和实验中,研究了导引磁场大小对RKA锁相特性的影响,结果表明,在1.6 T以下,RKA输出微波与种子源微波之间的相位差锁定值总体上随导引磁场的增大而减小,在细节上,呈现阶跃形式,即一定范围内导引磁场大小变化不会导致相位差的改变。实验研究表明,在导引磁场范围为0.6~1.2 T时,RKA锁定相位差随导引磁场的增大而减小,阶跃现象不明显。     

Nonlinear optical behaviors in a silver nanoparticle array at different wavelengths

The optical nonlinearities of an Ag nanoparticle array are investigated by performing Z-scan measurements at the selected wavelengths (400, 600, 650, and 800 nm). The nonlinear refraction index in the resonant region (around 400 nm) exhibits a significant enhancement by two orders compared with that in the off-resonant region (around 800 nm)), and exhibits an sign alternation of the resonant nonlinear absorption, which results in a negligible nonlinear absorption at a certain excitation intensity. Moreover, a low degree of nonlinear absorption was measured at the edges of the resonant region (600 and 650 nm), which is attributed to the competition of the saturated absorption and the two-photon absorption processes.     

Optical Properties of Co-BaTiO3/Mg（100） Nano-Composite Films Grown by Pulsed Laser Deposition Method

Co nanoparticles embedded in a BaTiO3 matrix, namely Co-BaTiO3 nano-composite films are grown on Mg（100） single crystal substrates by the pulsed laser deposition （PLD） method at 650℃. Optical properties of the CoBaTiO3 nano-composite films are examined by absorption spectra （AS） and photoluminescence （PL） spectra. The results indicate that the concentration of Co nano-particles strongly influences the electron transition of the Co BaTiO3 nano-composite films. The PL emission band ranging from 1.9 to 2.2eV is reported. The AS and PL spectra suggest that the band gap is in the range of 3.28-3.7eV.     

LOW-FREQUENCY INTERNAL FRICTION STUDY FOR SrBi2Ta2O9 FERROELECTRIC CERAMICS

Low-frequency internal friction (IF) of SrBi₂Ta₂O₉(SBT) ceramics has been measured at temperatures ranging from 293 to 623 K. Two IF peaks, with their locations around 393 K (P1) and 569 K (P2) (f≈1.58 Hz), respectively, are observed. P1 is found to be associated with a relaxation process with activation energy of 0.97 eV and pre-exponential factor of 3.58×10^-14 s. Peak shape analyses reveal that P1 can be well described by a broadened Debye peak with the width parameter β from 2.70 to 2.92. The mechanism responsible for P1 is proposed to be relaxation of oxygen vacancies near domain walls(DWs). P2 is considered to arise from viscous motion of DWs since it shows characteristics of static hysteresis type. Comparisons for the IF behavior between SBT and Pb(Zr, Ti)O₃(PZT) suggest that in SBT oxygen vacancies are much less localized near DWs than that in PZT. This result provides a possible explanation for the weak DW pinning due to oxygen vacancies in SBT.