一个新的具有大的吸收截面的双光子引发剂的合成和非线性光学性质

E,E-1,4-Bis（4＇-N,N-diphenylaminostyryl）-2,5-dimethoxybenzene （DPAMOB） has been synthesized by a simple and effective solid phase Wittig reaction and characterized by 1^H NMR spectra and elemental analysis, Linear absorption, single-photon induced fluorescence and two-photon induced fluorescence spectra were experimentally studied. The new dye has a large two-photon absorption （TPA） cross-section of σr= 1007,2 GM [1 GM= 1 × 10^-50 cm^4·s/（photon molecule）] at 800 nm measured by the two-photon induced fluorescence method. The experimental results confirm that DPAMOB is a good TPA chromophore and can successfully initiate two-photon photopolymerization of ethoxylated trimethylolpropane triacrylate esters （SR454）. Finally, a microstructure has been fabricated by use of DPAMOB as initiator.     

Production of helium projectile fragments in {16O－emulsion interactions at 4.5 A GeV/c

The measurements of partial production cross sections of the multiple helium projectile fragments emitted at 4.5 A GeV/c {}^{16}O－Em interactions are reported. We have studied the production rate of helium projectile fragments due to fragmentation of {}^{16}O ions and compared it with that obtained from different projectiles at various energies. The dependence of on the mass number of the incident beams is formulated. The multiplicity distributions of the helium fragments produced in {}^{16}O－Em interactions at different energies exhibit Koba－Nielson－Olesen (KNO) scaling. The correlation of helium projectile fragments and target fragments is also investigated and it is found that the average of target fragments is increased with the decrease of the number of helium fragments in peripheral interactions.     

用基态特征γ射线计算同质异能态反应截面的公式及其应用

根据人工放射性的生长与衰变规律, 推导出一个在特殊情况下用基态特征γ射线计算同质异能态反应截面的公式, 并据此公式用活化法以⁹³Nb(n,2n)^92mNb反应截面为中子注量标准对¹²⁸Te(n,2n)^127mTe反应截面进行了测量. 由能量为(14.1±0.2)和(14.6±0.3)MeV的中子引发的¹²⁸Te(n,2n)^127mTe反应截面值分别为(737±69)和(853±82)mb. 单能中子用T(d,n)⁴He反应获得, 其能量用铌锆截面比法测定. 为减小热中子的(n, γ)反应的影响, 在辐照过程中对样品进行了包镉处理.     

Effective Stimulated Emission Cross-Sections of Poly(Phenylene Vinylene) Copolymers in Toluene Solution

We report optical gain measurements in four different copolymers polyp-phenylene-co-[2,5-dioctyloxy-p-phenylene-bis-2(4-nonyl phenyl) vinylene]nonyl-PpPV, polym-phenylene-co-[2,5-dioctyloxy-p-phenylene-bis-2(4-methyl phenyl) vinylene]methyl-PmPV, polyp-phenylene-co-[2,5-dioctyloxy-p-phenylene-bis-2(4-methyl-phenyl) vinylene]methyl-PpPV, polyp-phenylene-co-[2,6-naphthylene-bis-2(4-nonyl phenyl) vinylene]nonyl-PpPV-NV in toluene. The copolymers are related to poly(phenylene vinylene) and have been synthesized via Horner–Emmons polycondensation reaction. The optical gain determined from the amplified spontaneous emission (ASE) intensity is dependent on the excited stripe length. The net optical gain coefficients are found to vary between 0.1 cm^–1 in nonyl-PpPV to 2.5 cm^–1 in methyl-PmPV under nanosecond pulse excitation. The gain for Rodamine 6G was also measured under the same experimental condition and was used to determine the stimulated emission cross-sections for the four polymers and found to be _SE(peak)= 6.7 × 10^–20 cm² for nonyl-PpPV, _SE(peak)= 1.7 × 10¹⁸ cm² for methyl-PmPV, _SE(peak)= 1.4 × 10^–18 cm² for methyl-PpPV, and _SE(peak)= 1.5 × 10^–18 cm² for nonyl-PpPV-NV.     

Effective atomic numbers of some vanadium and nickel compounds for total photon interactions using transmission experiments

Effective atomic numbers of V₂O₃,VO₂,VF₃,NH₄VO₃,VF₄,NiF₂,NiCl₂,NiF₂4H₂O,NiCl₂6H₂O,Ni(ClO₄)₂6H₂O were measured in the X-ray energy range 15.746- using an Si(Li) detector. The measured values are compared with the theoretical ones calculated using WinXcom.     

Nonlinear equations of flexural-flexural-torsional oscillations of rotating beamswith arbitrary cross-section

A system of three nonlinear partial differential equations describing the flexural-flexural-torsional vibrations of a rotating slender cantilever beam of arbitrary cross-section is derived using Hamilton’s principle. It is assumed that the center of gravity and the shear center are at different points. The interaction between flexural and torsional vibrations is accounted for in the linear and nonlinear parts of model Published in Prikladnaya Mekhanika, Vol. 44, No. 5, pp. 123–132, May 2008.     

荧光染料和磷光染料激子形成截面的比较

为了比较单线态激子与三线态激子形成截面的大小,作者将荧光染料4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) 和磷光材料factris-(2-phenylpyridine) iridium [Ir(ppy)₃]共掺杂在N-vinylcarbazole (PVK)中作为发光层,制作了多层有机电致发光器件。通过对其光致发光及电致发光特性的研究,计算出Ir(ppy)₃激子的形成截面比DCJTB激子的形成截面大得多。     

界面脱胶圆夹杂对SH波散射的远场解

采用Green函数方法和复变函数法研究了SH波对界面脱胶圆夹杂的散射问题,并给出 了远场解答. 首先,沿双质材料界面将整个空间分成上下两部分, 在下半空间,给出了在水 平表面上任意一点承受时间谐和的出平面线源载荷作用时的位移函数,取该位移函数作为 Green函数. 其次,在下半空间,利用相关文献给出的Green函数,在上下空间连接时在双质材料界面处满足 连续性条件,构造出半圆形脱胶裂纹,进而求出应力和位移的表达式,建立积分方 程组, 给出了散射波远场位移模式和散射截面的解答, 分析了在不同参数变化时SH 波散射的远场特性. 结果表明,脱胶结构的存在对位移和散射截面有较大的放大作用.     

Synthesis and properties of tribranched chromophores with triazine and fluorene units

Two tribranched chromophores,1,3,5-triazine as electron deficient core,9,9-dimethylfluorene asπ-conjugated bridge, diphenylamino(4a) and naphthylamino(4b) as electron-donating end-groups,were successfully prepared via Buchwald-Hartwig coupling reaction.Their linear photophysical and two-photon absorption(TPA) properties were investigated by absorption, fluorescence and nonlinear transmission method,respectively.The absorption cut-offs of the chromophores are below 550 nm and both chromophores have strong fluorescence emission.The compound 4a(206.3 GM) exhibits larger TPA cross-section than 4b (57.8 GM) in the femtosecond regime at 800 nm.     

X-ray diffraction profiles of Si nanowires with trapezoidal cross-sections

Comparisons of the experimental and calculated X-ray diffraction profiles have been made for Si nanowires with trapezoidal cross-sections. Examined samples are periodically arranged nanowires prepared on a silicon-on-insulator wafer by electron-beam lithography, so that they are isolated from Si substrate. The nanowire periodicity gives rise to diffractions at additional reciprocal lattice points, which we employ to avoid the mixture of the diffraction from the Si substrate. The experimental diffraction profiles are found to be in good agreement with the square modulus of the Fourier transform of the trapezoidal cross-sections determined from transmission electron micrographs.