金属表面在反射方向产生光学二次谐波的研究(Ⅰ)

用Rudnick和Stern引入的唯象参数“a”和“b”来描述表面电流,本文推导了金属表面在反射方向产生的光学二次谐波的表达式.由此证明了:从谐波信号随入射光偏振态的变化可以直接得到关于参数“a”的信息.和过去的实验相比,这种方法能更加精确、可靠地测定“a”的数值.     

α—取代桂皮酰胺类化合物~1H NMR、UV及顺反构型的研究

本文报道了24个α被13种基团取代的桂皮酰胺类化合物的_1H NMR和UV数据。用经验公式计算了β-H的化学位移。结果表明,其测定值与计算值的比较可用于推断这类化合物的顺反构型。它们苯基上质子的化学位移也可为判断构型提供依据。对于成对的化合物,酰胺氮上质子的化学位移及紫外光谱亦有助于判断构型。     

绞股蓝种子中α-桐酸的定性和定量分析

用RTX-5MS弹性石英毛细管柱(0.25mm×30m×0.25μm)气相色谱-质谱法(GC-MS)分析绞股蓝种子中的α-桐酸。用相对保留时间和质谱对α-桐酸进行定性分析,用内标法对α-桐酸进行定量分析。结果表明,绞股蓝种子中含有α-桐酸,在0.34—1.37mg/mL范围内线性关系良好(R2=0.9996),平均回收率为99.91%,且绞股蓝种子中α-桐酸的含量为66.9mg/g。实验结果为以后的绞股蓝种子中α-桐酸的开发与利用提供理论依据。     

Cr,Mo,Ni在α-Fe(C)中占位、键合性质及合金化效应的第一性原理研究

基于密度泛函理论第一性原理方法,采用广义梯度近似下的PW91泛函形式,计算了合金元素Cr,Mo,Ni固溶于α-Fe(C)的电子结构,从晶格畸变、结合能、态密度、重叠布居及差分电荷密度等计算结果出发探讨了合金元素在α-Fe(C)中占位、键合性质及其合金化效应,结果表明:Cr优先占据铁素体晶胞顶角位置,而Mo,Ni优先占据体心位置;Cr与晶胞的结合能最大,晶胞最稳定,Ni次之,Mo最低;Cr,Mo,Ni在晶胞中都存在金属键、共价键和微弱离子键的共同作用,成键轨道主要是Cr3d与Fe3d,Mo4d与Fe3d,Ni3d与Fe3d,C2p的交互作用形成的;Cr与晶胞原子间的键合作用强,晶胞的稳定性好,对增强钢材的机械性能帮助较大,Ni的键合作用较弱,但还是能保持晶胞的稳定性,Mo虽然键合作用强,但反键作用也非常强,使晶胞的稳定性大大降低,对钢材的机械性能危害较大.     

A design strategy of achievable linear optics for a complex storage ring lattice

A design strategy is discussed in this paper,and it provides much convenience for effectively exploring achievable linear optics and globally investigating the flexibility of a complex lattice with superperiodicity.A matching method of fractional steps,which means separately finding the standard cell setting and the matching cell setting,is adopted to simplify the complexity of the linear beam optics design in the complex lattice.The multi-objective genetic algorithm is used to find most of all the stable linear optics,and reach a target solution after multi-generational propagation,both in the standard cell and the matching cell.A fitting algorithm with gradient information is used to restore the periodicity and symmetry of the lattice,and finely adjust the linear optics for further optimization.This design strategy is applied in the Shanghai Synchrotron Radiation Facility(SSRF)storage ring,and the results are presented.     

O(α_sv~2) correction to J/ψ plus η_c production in e~+e~- annihilation at √s=10.6 GeV

Based on the nonrelativistic QCD factorization approach, O(α_sv2) corrections to J/ψ plus η_c production in m e⁺e^- annihilation at √s=10.6 ≥v are calculated in this work. The numerical results show that the correction at α_sv2 order is only about a few percent of the total theoretical result. This indicates that the perturbative expansions become convergent and that a higher order correction will be smaller. The uncertainties from the long-distance matrix elements, renormalization scale and the measurement in the experiment are also discussed. Our result is in agreement with the previous result by Jia.     

C,igahertz longitudinal acoustic phonons originating from ultrafast ligand field transitions in hematite thin films

The creation and propagation of longitudinal acoustic phonons （LAPs） in high quality hematite thin films （α-Fe203） epitaxially grown on different substrates （BaTiO3, SrTiO3, and LaAlO3） are investigated using the femtosecond pump- probe technique. Transient reflection measurements （AR/R） indicate the photo-excited electron dynamics, and the initial decay less than 1 ps and the slow decay of -500 ps are attributed to the electron-LO phonon coupling and electron-hole nonradiative recombination, respectively. LAPs in α-Fe2O3 film can be created by ultrafast excitation of the ligand field state, such as the ligand field transitions under 800-nm excitation as well as the ligand to metal charge-transfer with 400- nm excitation. The strain modulations of the sound velocity and the out-of-plane elastic properties are demonstrated in α-Fe2O3 film on different substrates.     

应变对单层砷烯结构拉曼散射的影响

应用密度泛函理论对应变下的单层砷烯拉曼光谱的变化进行研究.由于材料的结构对称性较低，由外部应力诱发的形变不仅可以造成拉曼模式分裂，还可以引发拉曼模式偏移.计算表明：拉曼峰位的变化与应变正相关，建立了应变与峰位移动间的定量关系，为在实验中识别砷烯结构的应变提供依据.