飞秒光脉冲Z扫描技术测量纳米银颗粒非线性折射率

本文首次报道了用飞秒脉冲光Z扫描技术测量纳米银悬浮粒子的非线性折射率。从物理机制及理论上对Z扫描进行了分析,并对纳米悬浮粒子的有效长度进行了估算。利用标准样品对系统进行了标定。最后得到了纳米银粒子的非线性折射率为6.75×10^-10esu.     

LD泵浦Nd:YVO4/KTP/BBO紫外激光器

本文报道在国内首次实现的LD泵浦的四倍频连续紫外激光器的实验结果.首先研究了LD泵浦的Nd:YVO₄激光器,在普通平-平腔结构下,得到斜效率55.68%,激光输出波长1064nm;利用KTP作为倍频晶体,实现腔内倍频,在泵浦功率11.85W时得到绿光(532nm)输出1.35W,光-光转换效率11%;用BBO晶体进行外腔谐振倍频,得到紫外光(266nm)输出.     

高效全固化263nm紫外激光脉冲的产生

运用半导体泵浦的Nd:YLF调Q倍频激光器输出的527nm波长激光和BBO晶体直接进行了外腔谐波倍频的实验研究.采用较小的基波光束尺寸和长聚焦相结合的方法实现了高效全固化263nm紫外激光脉冲的大功率输出.基波功率为6.0W时,紫外263nm激光输出780mW,转换效率达13%,实验中还发现紫外输出光束质量很好.     

飞秒光脉冲光纤放大增益特性的实验研究

报道了掺Ｅｒ＾３＋光纤激光器输出１．５３１μｍ波长飞秒激光脉冲增益放大的实验研究结果,将自起振相加脉冲摹参Ｅｒ＾３＋光纤激光器输出的飞秒激光脉冲注入掺Ｅｒ＾３＋光纤放大器中进行放大,分别采用正向和逆向抽地这的方式,得到了最高放大倍数５５倍（１７．４ｄＢ）和６４倍（１８．１ｄＢ）的增益,对应的最大单脉冲能量（峰值功率）分别为０．３８４ｎＪ（７５２Ｗ）０．４５２ｎＪ（１２９５Ｗ）,脉冲重复率为２０．８     

Experimental studies of high order soliton compression effect and gain characteristics in femtosecond laser pulses Er 3+-doped fiber amplifier

Seed laser pulses with average power of 146 μW and pulse duration of 480 fs were amplified to 14.5 mW. The pulse duration was compressed to 260 fs using 6 m high concentration E³⁺ _r -doped fiber under forward pumping. The amplified signal pulse energy was 0.691 nJ (corresponding to a peak power of 2 657.7 W) and the repetition rate was 20.84 MHz. Spectrum breakup was observed simultaneously. The spectrum of pulses amplified by 3 m E³⁺ _r -doped fiber remains a single peak under different pump power. The amplified pulse duration was compressed abnormally with the increasing pump power using the backward pumping; that is, the amplified pulses were compressed with the increasing pump power under low pump power. When the pump power reached 38 mW, the shortest amplified pulse duration was 309 fs. With further increase in pump power, the amplified pulses began broadening, accompanied by a single peak spectrum under different pump power.     

以N,N′-二甲基甲酰胺为增敏剂催化光度法测定痕量锰

基于活化剂氨三乙酸和增敏剂Ｎ,Ｎ′－二甲基甲酰胺存在下,锰（Ⅱ）催化高碘酸钾氧化夜蓝的反应,拟定了测定痕量锰的新催化光度法。讨论了反应机理。本法在有机溶剂Ｎ,Ｎ′－二甲基甲酰胺存在下,灵敏度显著提高,检出限为０．１０ｎｇ／ｍＬ,相对标准偏差为２．８％（ｎ＝８）,方法用于铝合金中锰的测定,结果满意。     

Some Properties of Free Boundary for Solution of Porous Medium Equation with Gravity Term in One-dimension

Consider the degenerate parabolic equation (porous medium equation with gravity term): u_t = (u^m)_{xx} + (u^n)_x, -∞ < x < ∞, t > 0, m > 1 u(x, 0) = u_0(x), -∞ < x < ∞ The main results consist of the estimation of t^∗_i called waiting time, the behavior of pressure V = \frac{m}{m-1}u^{m-1} near a vertical or a nonvertical part of ς_i(t) and a condition of that ς_i(t) is continuously differentiable.     

Experimental and Computational Studies on Uranium Diazomethanediide Complexes

Uranium diazomethanediide complexes can be prepared and their synthesis, structure and reactivity were explored. Reaction of the uranium imido compound [η⁵-1,2,4-(Me₃Si)₃C₅H₂]₂U=N(p-tolyl)(dmap) ( 1 ) or [η⁵-1,3-(Me₃C)₂C₅H₃]₂U=N(p-tolyl)(dmap) ( 4 ) with Me₃SiCHN₂ cleanly yields the first isocyanoimido metal complexes [η⁵-1,2,4-(Me₃Si)₃C₅H₂]₂U(=NNC)(μ-CNN=)U(dmap)[η⁵-1,2,4-(Me₃Si)₃C₅H₂]₂ ( 2 ) and {[η⁵-1,3-(Me₃C)₂C₅H₃]₂U[μ-(=NNC)]}₆ ( 5 ), respectively. Both compounds exhibit remarkable thermal stability and were fully characterized. According to density functional theory (DFT) studies the bonding between the Cp₂U²⁺ and [NNC]²⁻ moieties is strongly polarized with a significant 5 f orbital contribution, which is also reflected in the reactivity of these complexes. For example, complex 5 acts as a nucleophile toward alkylsilyl halides and engages in a [2+2] cycloaddition with CS₂, but no reaction occurs in the presence of internal alkynes.     

Bimetallic Cooperatively Catalyzed Heteroarylation of Aryl Fluorosulfates

We report a bimetallic cooperatively catalyzed C−H activation strategy for the heteroarylation of easily accessed aryl fluorosulfates which were introduced to sulfur fluoride exchange (SuFEx) click chemistry by Sharpless. This novel catalytic system enables highly chemoselective synthesis of important heterobiaryl motifs through the coupling of aryl fluorosulfates in the absence of prefunclization and directing groups. Moreover, this strategy has good functional group tolerance and a wide range of substrates and could be successfully used for the synthesis of bioactive molecules tafamidis.     

Structure and spectra character of cobalt nickel sulfate twelvehydrate (CNSH) single crystal

The title compound CoNi(SO₄)₂ · 12H₂O has been prepared and its crystal structure determined by single crystal X‐ray differaction at room temperature. The CNSH crystal structure belongs to the monoclinic space group C2/c,a = 9.966(2) Å, b = 7.2265(14) Å, c = 24.218(5) Å, β = 98.32(3)°, V = 1725.9(6) ų, z = 4, Dc = 2.024 gcm⁻³. The optical transmission character of CNSH crystal in aqueous solution is discontinuous in the range from ultraviolet to near IR wavelengths. The relationship between the structure and the optical transmission property is further discussed. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)