荧光猝灭法测定茶叶中的钐和钕

在pH为3.20~3.40的弱酸性介质中,稀土金属元素钐(Ш)与钕(Ш)均能使刚果红的荧光显著猝灭。实验表明:刚果红的最大发射波长(λem)为419nm,在钐(Ш)和钕(Ш)的存在下,刚果红荧光猝灭程度(ΔF)与钐(Ш)和钕(Ш)的浓度呈线性关系。钐(Ш)和钕(Ш)的检出限分别为0.0826#g/mL和0.1088#g/mL,线性范围为0.004~2.8mg/mL和0.004~1.6mg/mL。文中优化了反应条件的影响,据此发展了以刚果红为荧光探针的灵敏、简便、快速测定钐(Ш)与钕(Ш)的新方法。将方法用于茶叶中钐(Ш)与钕(Ш)含量的快速测定,结果满意。     

稀土元素钐的光电流光谱

利用光电流信号研究了稀土素钐的原子光谱。钐原子被染科激光（由氩离子激光泵浦若丹明６Ｇ）激发。实验中探测了从６０８．０００－６２１．０００ｎｍ的大约２０条谱线，对其中大部分谱线作了指认，发现了一些新谱线。对钐原子中光电流信号的正，负特性作了讨论。     

钐的聚酰亚胺配合物的微波辐射固相配位合成和表征

钐离子（Ⅲ）与苯代三聚氰胺和2，4－甲苯基二异氰酸酯（TDI）生成的聚脲再与均苯四酸二酐生成的聚酰亚胺的固相配位反应。考察了微波辐射时间（功率）、稀土离子和聚合物的配比以及温度等因素对配合物产率及配合物中钐离子含量的影响，测量了配合物的红外光谱、拉曼光谱、扫描电镜、^13C固体核磁共振及X－射线粉末衍射等，并推测了配合物可能的结构。测定了配合物中钐离子的含量，通过荧光发射光谱测量了配合物的荧光发射强度，并与相应的常规加热配位进行比较。通过磁化曲线测量了配体和配合物的磁性能。实验结果表明：此类配合物不具有钐离子的特征荧光峰，钐离子的第一激发态能级和配体的三重态能级之间不能匹配。另外配合物显示出稀土离子的优良的磁性能。     

四(对甲氧基苯基)钐卟啉与牛血清白蛋白相互作用的研究

合成了四(对甲氧基苯基)钐卟啉,利用荧光光谱法研究了四(对甲氧基苯基)钐卟啉与牛血清白蛋白(BSA)的相互作用。结果表明四(对甲氧基苯基)钐卟啉对BSA的荧光有较强的猝灭作用,属于静态荧光猝灭,由实验数据求得猝灭速率常数K_q=1.3842×10~(13)L·mol~(-1)·s~(-1)、结合常数K_△=3.4610×10~4L·mol~(-1)、结合数n≈1。     

稀土配合物的时间分辨荧光光谱法研究(Ⅱ)——Eu,Sm-DBM-TOPO体系的荧光衰减动力学特性和激光诱导时间分辨荧光光谱

本文以Nd:YAG泵浦的染料激光器为激发光源,门控光学多道分析仪为检测器,自制的触发器和荧光盒组装成一台激光诱导时间分辨光谱装置。采用此装置研究了在表面活性剂Triton X-100存在下铕、钐-二苯甲酰甲烷-三正辛基氧化膦(Eu、Sm-DBM-TOPO)体系的激光诱导发光光谱特性和荧光衰减动力学特性。讨论了荧光发射过程中的能量传递机制。拟定出测定痕有铕和钐的时间分辨光谱方法,用于高纯稀土氧化物等样品中痕量铕和钐的测定,结果满意。     

稀土配合物的时间分辨荧光光谱法研究(Ⅱ)——Eu,Sm-DBM-TOPO体系的荧光衰减动力学特性和激光诱导时间分辨荧光光谱

本文以Nd:YAG泵浦的染料激光器为激发光源,门控光学多道分析仪为检测器,自制的触发器和荧光盒组装成一台激光诱导时间分辨光谱装置。采用此装置研究了在表面活性剂Triton X-100存在下铕、钐-二苯甲酰甲烷-三正辛基氧化膦(Eu、Sm-DBM-TOPO)体系的激光诱导发光光谱特性和荧光衰减动力学特性。讨论了荧光发射过程中的能量传递机制。拟定出测定痕有铕和钐的时间分辨光谱方法,用于高纯稀土氧化物等样品中痕量铕和钐的测定,结果满意。     

稀土氨羧络合物的吸收光谱研究

本文系统地研究了EDTA,NTA,CyDTA,TTHA与镨,钕,钐,铕,锹,铒络合物的可见光吸收光谱及三阶导数光谱,并以Nd,Ho-TTHA体系测定了混合稀土氧化物中的Nd,Ho,首次以Sm-DTPA体系的三阶导数我谱成功地进行了纯氧化镧中杂质氧化钐的测定。     

负载弦之演示教具

介绍一自制的负载弦教具，5颗沿铀向充磁的圆柱状钐钴磁铁穿在细钓鱼线上，作为负载弦之负载质点，再以可调频率的交流电磁化马蹄形电磁铁，使得马蹄形电磁铁对圆柱状钐钴磁铁施与周期性的引力及斥力，启动负载弦的各个简正模式．此自制的负载弦教具可定量演示教科书中理论计算的结果．     

质子辐照对永磁合金微观结构演化的研究

钐钴和钕铁硼稀土永磁合金已经广泛应用于粒子加速器的波荡器和其他器件中,作为加速器的重要组成部分,永磁合金在辐照环境中长期服役会出现磁性能损失的现象,这会影响束流的品质.为了探讨产生这个现象的微观机理,采用透射电镜对质子辐照前后的钐钴和钕铁硼稀土永磁合金进行了微观结构演化的表征和分析,统计了由辐照析出的纳米晶体积密度和粒径分布,并讨论了微观结构演化对宏观磁性能损失的影响.结果表明,随着质子辐照损伤程度的增加,永磁合金的微观结构从单晶结构转变为纳米晶多晶结构,且纳米晶和基体的晶体结构相同.钕铁硼的纳米晶体积密度先增大后减小,粒径分布先增大后不变;钐钴的纳米晶体积密度逐渐减小,粒径逐渐增大.在2 dpa的质子辐照损伤程度下,钕铁硼稀土永磁合金比钐钴永磁合金的非晶化趋势更明显.     

控制气氛光谱法测定高纯氧化铕中14个稀土杂质元素

Brukl等较早地报告了氧化铕中钐的测定;Kustas等以溶液干渣法测定了氧化铕中14个稀土元素,可对98.8%纯度的氧化铕进行快速测定;Osumi等报导了在氩气气氛中直流电弧粉末法测定氧化铕中稀土元素;Murty采用氧气气氛直流电弧粉末法测定氧化铕中钕、钐、钆、铽、镝等五个稀土元素。这些方法对于测定高纯氧化铕中14个稀土元素都有不足之处。     

Kinetics and Phase Transformations during the Decomposition of Supersaturated Solid Solutions of Magnesium in Mg–Dy–Sm Alloys

Kinetics and phase transformations are studied for the previously unconsidered decomposition of supersaturated solid solution in magnesium-based alloys Mg–Dy–Sm. The decomposition of solid solution slows when there is an increase in % Dy: % Sm ratio in the alloys. Mg–Sm and Mg–Dy alloys grow harder when Dy and Sm are added to them, respectively. Products of decomposition in ternary Mg–Dy–Sm alloys are the same as in binary alloys Mg–Dy and Mg–Sm but contain combinations of Dy and Sm.     

Reentrant ferroelectricity in liquid crystals

The ferroelectric (Sm C*)-antiferroelectric (Sm C*A)-reentrant ferroelectric (re Sm C*) phase temperature sequence was observed for systems with competing synclinic-anticlinic interactions. The basic properties of this system are as follows: (i) the Sm C* phase is metastable in the temperature range of the Sm C*A; (ii) the helix handedness inverts at both Sm C*-Sm C*A and Sm C*A-re-Sm C* phase transitions; (iii) the threshold electric field that is necessary to induce synclinic ordering in the Sm C*A phase decreases near both Sm C*A-Sm C* and Sm C*A-re-Sm C* phase boundaries. All these properties are properly described by a simple Landau model that accounts for nearest neighboring layer steric interactions and quadrupolar ordering only.     

ZnS:Mn2+,Sm3+中Mn2+、Sm3+中心之间能量传递的分时光谱研究

前一阶段我们比较系统地研究了ZnS:Mn2+,Sm3+材料中Mn2+中心和Sm3+中心之间的能量传递。通过测量ZnS:Mn2+、ZnS:Sm3+和ZnS:Mn2+,Sm3+三种材料的发射光谱、激发光谱、选择激发发光光谱,证实了Mn2+中心和Sm3+中心之间存在偶极—偶极相互作用的无辐射能量传递。为了进一步研究Mn2+中心和Sm3+中心之间的相互作用及其物理特点,我们又仔细测量了上述三种不同类型材料的分时光谱,这不仅可以更清楚地了解激发停止后Mn2+中心和Sm3+中心之间的相互作用,而且有效地解决了Mn2+中心发射光谱和Sm3+中心某些特征光谱线交叠引起的测量发光衰减的困难。     

稀土离子（Sm3+）有机配合物的合成及光谱性能的研究

本文合成了稀土离子（Sm3+）的三种β二酮类二元有机配合物Sm(HFA)3，Sm(TTA)3和Sm(DBM)3.对配体HFA，HTTA和DBM及配合物Sm(HFA)3，Sm(TTA)3和Sm(DBM)3的吸收光谱和荧光光谱进行了测试与分析.发现Sm(HFA)3和Sm(TTA)3在645 nm处（对应Sm3+的4G5/2→6H9/2跃迁）有很强的荧光峰，可以观察到明显的红色荧光.并且分析了配合物和配体的能级结构、配体的取代基、配体结构对称性以及C-H键含量对配合物光谱性能的影响，证明了HTTA是Sm3+发红色荧光的优良配体.     

Shape evolution for Sm isotopes in relativistic mean-field theory

The evolution of shape from the spherical to the axially deformed shapes in the Sm isotopes is investigated microscopically in relativistic mean-field theory. The microscopic and self-consistent quadrupole deformation constrained relativistic mean-field calculations show a clear shape change for the even-even Sm isotopes with N = 82-96. The potential surfaces for ¹⁴⁸Sm, ¹⁵⁰Sm and ¹⁵²Sm are found to be relatively flat, which may be the possible critical-point nuclei. By examining the single-particle spectra and nearest-neighbor spacing distribution of the single-particle levels, one finds that the single-particle levels in ¹⁴⁸Sm , ¹⁵⁰Sm, and ¹⁵²Sm distribute more uniformly.     

Effects of Li~+ on photoluminescence of Sr_3SiO_5:Sm~(3+) red phosphor

The structure and photoluminescence (PL) properties of Sr3SiO5 : Sm3+ and Li+-doped Sr3SiO5 : Sm3+ red-emitting phosphors were investigated. Samples were prepared by the high-temperature solid-state method. PL spectra show that the concentration quenching occurs when the Sm3+ concentration is beyond 1.3 mol% in Sr3SiO5 : Sm3+ phosphor without doping Li+ ions. The concentration-quenching mechanism can be explained by the electric dipole-dipole interaction of Sm3+ ions. The incorporation of Li+ ions into Sr3SiO5 : Sm3+ phosphors, as a charge compensator, improves the PL properties. The lithium ions also suppress the concentration quenching in Sm3+ with concentration increased from 1.3 mol% to 1.7 mol%.     

Samarium valence changes and reactive interdiffusion at the Si(111)-Sm interface

Synchrotron radiation photoemission studies show that the Si(111) 2×1-Sm interface has a complex morphology involving sequential formation stages with different Sm valence states. For metal coverages up to 2–3 Å, Sm atoms appear only in a divalent state. At higher coverages (up to 10–15 Å) the trivalent Sm configuration dominates and large chemical shifts of Si 2p and Sm 4f and 5p levels are observed. The Sm valence change is related to the onset of the reactive interdiffusion of Sm and Si.     

Valence variations in the monolayer regime of Sm on the Nb(110) surface

Sm overlayers in the monolayer regime, deposited on a Nb(110) single-crystal surface at room temperature, have been studied by means of high-resolution photoelectron spectroscopy of the Nb 3d_5/2 core level and the Sm valence band. In the submonolayer regime, the Sm valence varies from mainly divalent for very low coverages to essentially trivalent close to a complete monolayer. Above 1 ML, a new divalent component appears in the Sm 4f spectra, corresonding to divalent Sm in the second layer. The mixed valence in this overlayer system is concluded to be heterogeneous (all Sm atoms have integer but site-dependent valence). Sm forms ordered overlayers on Nb(110) and the Sm growth is consistent with a layer-by-layer growth mode (Frank–van der Merwe growth).     

Comparison of plume expansion in femtosecond laser ablation on oxidized and non-oxidized Sm surfaces

Time development of Sm⁺ and Sm ablation plume produced by the femtosecond laser irradiation has been investigated. The two-dimensional spatial profiles of Sm and Sm⁺ emitted from oxidized and non-oxidized Sm surface were visualized using a planar laser-induced fluorescence method. It was observed that the flow velocity of Sm⁺ is much faster than that of Sm plume in both surfaces. The plumes from the oxidized Sm surface show higher velocity than that from non-oxidized surface, which is originated by the small electric conductivity at the surface. Expansion property observed for Sm⁺ and Sm plume in the oxidized Sm surface ablation implies the formation of the Knundsen layer nearby the surface. Meanwhile, continuous emission of Sm indicates the large contribution of heating effect to emission process at the non-oxidized surface. We conclude that the fsLA process strongly depends on the electric property of the ablated surface and the heating effect contributes to the particle emission process on the conductive material surface.     

Geometry of the valence transition induced surface reconstruction of Sm(0001)

We present a structural determination of the surface reconstruction of the Sm(0001) surface using surface x-ray diffraction, scanning tunneling microscopy, and ab initio calculations. The reconstruction is associated with a large (22%) expansion of the atomic radius for the top monolayer surface Sm atoms. The mechanism driving the surface reconstruction in Sm is unique among all elements and is connected to the strong correlations of the 4f electrons in Sm and the intermediate valence observed in certain Sm compounds. The atoms constituting the top monolayer of Sm(0001) have vastly different chemical properties compared to the layer underneath and behave as if they were an adsorbate of a different chemical species.