尖晶石型LiMn2O4的低温制备

锂锰氧化物;溶胶凝胶法;尖晶石型LiMn2O4的低温制备     

SYSTEMATIC STUDY OF POLARIZATION OF TWO-PHOTON ABSORPTION IN SYMMETRY ASSIGNMENTS

In this paper, we have systematically analyzed the degenerate and nondegenerate two-photon polarization ratios of various point groups. We present the maximum of symmetry assignments of two-photon transition with the combination of degenerate and nondegenerate two-photon absorption. These results provide the theoretical basis for the experimental assignments.     

“PPAS” X-RAY ABSORPTION SPECTROSCOPY IN LASER-PRODUCED ALUMINUM PLASMA

We have developed and successfully demonstrated the "point projection absorption spectroscopy (hereafter abbreviated to PPAS)" technique to record keV X-ray absorption spectra in the coronal region of laser produced aluminum plasma which provides spatial information in the corona. Absorption spectrum of the Al Ⅻ 1s²-1s2p resonant line for time delays up to 250, 500 and 750 ps after the peak of the incident laser pulse have been observed. Analysis of an absorption spectrum should allow a high spatial resolution (< 25μm) history of the absorbing ion population density to be determined. The 1-D hydro-code JB19 has been used to simulate the experiment and the predictions are compared to the observations. Such comparison can be useful in validating parts of the codes used for gain prediction on recombination X-ray laser transitions.     

The Two-Nucleon Mechanism for the Neutrinoless Double Beta Decay and the BCS Nuclear Wave Function

A method of using the Bardeen-Cooper-Schrieffer (BCS) nuclear wave function to treat the two-nucleon mechanism for neutiinoless double beta decay process 0⁺ → 0⁺ is proposed.The neutrinoless decay mode and the neutrinoless decay accompanied by a Majoron emission mode of ⁸²Se are studikd. Our cdculated results show that to reproduce the experimental value of γ^(ov) > 1.8 × 10²² yr for neutrinoless double beta decai of ⁸²Se the Majorana neutrino mass m_v < 6.2 eV and the mixing parameter of right-handed current η < 7.0 × 10^-6 In the emission with a Majoron mode the effective Majoron coupling to neutrino is deduced from the experimental value of γ^(ov,H) > 4.4 × 10²⁰ yr for ⁸²Se with the result H0> < 6.2 × 10^-4.     

胺草磷系列——晶Ⅰ和晶Ⅱ分子结构和晶体结构测定

胺草磷是一种合成除草剂,其晶体为无色片状,在无水乙醇和甲苯中能得到重新结晶。胺草磷晶Ⅰ和晶Ⅱ是胺草磷系列中的两个样品,均属于单斜晶系,空间群均为P2_{1/c,晶胞参数基本一样,aⅠ=8.575?,bⅠ=26.541?,cⅠ=7.063?,βⅠ=94.744°;aⅡ=8.575?,bⅡ=26.538?,cⅡ=7.073?,βⅡ=93.819°。分子粗结构模型均用直接法获得,并用全矩阵最小二乘法进行修正,最后RⅠ=0.10;RⅡ=0.11。结构中的苯环平面和硝基平面成垂直关系。晶Ⅱ比晶Ⅰ除草效果好。 关键词：}     

二甲亚砜硝酸钇的晶体结构

二甲亚砜硝酸钇Y(NO₃)₃·3DMSO晶体属单斜晶系,a=13.604(4)?,b=12.669(4)?, c=11.554(2)?, β=100.14(4)°,z=4。空间群为P2₁/n。用PW-1100四圆衍射仪收集强度数据,独立衍射点数为3615个。结构已用重原子法解出,用全矩阵和方块对角矩阵最小二乘方法修正结构参数,最后R因子为0.080。结构分析结果表明,围绕着钇离子的九个氧构成稍歪扭的“三帽三方棱柱”配位多面体。钇和配位氧之间 关键词：     

MnAlC永磁合金的中子衍射研究

用中子衍射技术研究了Mn_1.074Al_0.871C_0.055永磁合金的晶体结构和磁结构,Mn_1.074Al_0.871C_0.055为四角体心结构,从中子衍射谱线的拟合结果可以看出:0.992Mn和0.008C占据(0,0,0)晶位;0.082Mn、0.87lAl和0.047C占据(1/2,1/2,1/2)晶位,在不同晶位上的Mn原子的磁矩沿c轴方向反平行排列,把这些结果与Mn_1.09Al_0.91二元合金的中子衍射结果相比较,可以解释Mn_1.074Al_0.871C_0.055三元合金的磁性和机械性能都可获得明显提高的原因。 关键词：     

富镧混合稀土-镍贮氢材料CO,O2和H2O中毒的表面特征

本文用UPS,XPS研究了贮氢材料MlNi₅(Ml=La,Ce,Pr,Nd)的CO,O₂和H₂O的中毒,在UPS谱中,我们观察到在E_F以下峰α(0.3eV)和峰b(1.2eV)强度随中毒气体暴露量增加有显著变化,并向低动能端位移,逐渐形成肩峰,与此同时,峰c(6eV)和峰d(9.5eV)的强度随暴露量增加而增加,并有能量位移,配合XPS分析,分别确定相应的化学态。氧中毒后的MlNi₅,经300℃加氢还原,从UPS谱可以看到峰α,b强度增加;H₂O和CO中毒后,在超高真空条件下,分别经300℃加热处理,和Ar⁺剥离方法,均获得类似的效果,XPS分析进一步证实了这些结果。实验给出了贮氢材料MlNi₅中过渡金属镍的d电子与气体自由分子轨道间电荷转移的信息,为在实际应用中认识此类贮氢合金的表面催化中毒和再生提供了依据。 关键词：     

光解水α-Fe2O3电极表面的研究

本文利用Ar⁺轰击正分的α-Fe₂O₃表面,证明了轰击后的表面呈类FeO性质,存在Fe⁺⁺。提出了由于表面Fe⁺⁺的3d电子的催化作用,Fe⁺⁺能把吸附在它上面的H₂O先分解成OH-和H⁺,因而有助于提高光解水的效率的看法。用UPS和XPS等技术证实了类FeO表面吸附水后存在OH^-,确认Fe^{++关键词：}