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991.
在乙醇溶液中以邻菲咯啉(phen)、2,2’-联吡啶(bipy)和对氨基马尿酸(PAH,HL)为配体与铽离子(Tb(Ⅲ))合成了二元和三元稀土配合物。通过元素分析、差热-热重分析、紫外光谱、红外光谱分析,确定了配合物的组成为TbL3(1)、TbL3·phen·H2O(2)和TbL3·bipy·H2O(3),并讨论了配合物1~3的谱学性质和荧光性能。推测出羧基中的氧原子以桥式双齿的形式与稀土离子配位。由红外光谱和热分析测试确定的配合物1及配合物2中的水分子未参与配位。研究表明,铽配合物在489,583和621 nm处出现发射峰,它们分别归属于5D4→7F6,5D4→7F5,5D4→7F4和5D4→7F3的跃迁。其中544 nm处5D4→7F5跃迁的强度最强,配体的共平面性和共轭性越大,配合物的荧光性能越高,三元配合物TbL3·phen·H2O和TbL3·bipy·H2O的荧光强度优于二元配合物TbL3的荧光强度。 相似文献
992.
The adiabatic effective baryon-baryou interactions and dibaryon candidates are studied systematically with three constituent quark models based on different effective degrees of freedom:Glozman-Riska-Brown Goldstone boson exchange model based on constituent quark and Goldstone boson coupling;Fujiwara model based on constituent quark gluon coupling and Nijmegen one-boson exchange;QDCSM based on constituent quark and gluon coupling with quark delocalization and color screening.We find that the three models predicted the similar effective baryon-baryon interactions for roughly two thirds among the 64 states consisted of octet and decuplet baryons.The differences among three models and their separate characteristics are also studied. 相似文献
993.
本文研究了高掺杂Ga对ZnSe:Ga,Cu晶体中深中心光致发光谱带的影响。首次在高掺杂ZnSe:Ga,Cu中观察到了Cu-G带峰值位置随Ga浓度增大向长波方向移动的现象,并把它归因于高浓度的Ga和Cu相互作用,产生了谱峰为5580Å的新发射带,其半高宽(FWHM)大于Cu-G谱带的半高宽。此外还得到,随着Cu浓度增加,Cu-G带与Cu-R带强度之比减小。文中指出,Ga浓度较低时,ZnSe:Ga,Cu晶体与ZnSe:Cu晶体有相同的Cu深中心发射规律,即随着Cu浓度增大,Cu-G带与Cu-R带的强度比增大,由Cu-R发射带占优势逐渐过渡到Cu-G发射带占优势。 相似文献
994.
飞秒激光聚焦到LiF晶体内部, 晶体的加工形貌随偏振改变. 实验表明, 偏振方向平行于<110> 晶向时, 加工起点到表面的距离是<100>偏振下的1.08 倍; 而<110>偏振下加工终点到表面的距离是<100> 偏振下的1.01 倍. 为了解释加工形貌的偏振依赖, 建立了逆韧致辐射、雪崩电离和无辐射跃迁的模型, 首先, 价带电子通过强场电离和雪崩电离, 从激光中吸收能量跃迁到导带, 该过程用电子密度演化方程和傍轴非线性薛定谔方程描述, 求解方程得到导带电子密度; 其次, 导带电子通过无辐射跃迁过程释放能量给晶格, 由能量守恒计算出晶格温度沿激光传播方向的分布; 最后, 晶格温度超过熔点以上的区域被加工. 模拟结果显示, <110>偏振下加工起点到表面的距离是<100> 偏振下的1.03倍, 而<110>偏振下加工终点到表面的距离是<100>偏振下的0.981 倍, 与实验结果基本一致. 虽然Z扫描技术测量的非线性折射率随偏振方向变化, 但是非线性折射率的变化趋势与实验结果相反. 模拟和实验证明逆韧致辐射导致加工形貌随偏振变化. 相似文献
995.
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998.
Fabrication and magnetic properties of Ni-Zn nanowire arrays 总被引:2,自引:0,他引:2
Lihu Liu Haitao Li Shenghua Fan Jianjun Gu Yaopeng Li Huiyuan Sun 《Journal of magnetism and magnetic materials》2009,321(20):3511-3514
Ni-Zn nanowire arrays, with diameters of approximately 60 nm and lengths of around 40 μm, were fabricated by electrodeposition in porous anodic aluminum oxide templates at different electric potentials. X-ray diffraction observations demonstrated that the isolated nanowires had polycrystalline structure and that their phases changed with the deposition potential. The amount of deposited zinc in the nanowires increased with the deposition potential, whereas the amount of nickel decreased. Magnetic measurements showed that there was a gradual change of magnetism from isotropic to anistropic with increasing potential amplitude and that the coercivity reached a maximum value in the nanowire deposited at −1.35 V. 相似文献
999.
Xiaoyi Xie Yi Zhang Dong Li Yuxiu Fan Bin Huang Xiupei Yang 《Particle & Particle Systems Characterization》2023,40(10):2300039
Nanozymes can be used as favorable substitutes for natural enzymes because of their strong catalytic activity and good stability. At the same time, research on single-atom catalysts (SACs) with isolated metal atoms as active centers is also in full swing, showing excellent performance in a variety of catalytic reactions. With the in-depth study of SACs, people have a comprehensive understanding of them and put forward the concept of single-atom nanozymes (SAzymes) by combining nanozymes with SACs. As a new type of nanomaterial, SAzymes have attracted great interest due to their remarkable catalytic activity and rapid energy conversion. However, most applications of SAzymes are mainly in the fields of biomedicine and biosensing, and less research has been done in the field of the environment. Based on the amazing ability of nanozymes to detect and degrade pollutants, SAzymes are also used in the environmental field, and even they will show better capabilities. This review mainly analyses common transition metal-based SAzymes and describes their applications in the field of environmental pollutants. 相似文献
1000.
Let G be a connected graph with maximum degree Δ≥ 3.We investigate the upper bound for the chromatic number χγ(G) of the power graph Gγ.It was proved that χγ(G) ≤Δ(Δ-1)γ-1Δ-2+ 1 =:M + 1,where the equality holds if and only if G is a Moore graph.If G is not a Moore graph,and G satisfies one of the following conditions:(1) G is non-regular,(2) the girth g(G) ≤ 2γ- 1,(3)g(G) ≥ 2γ + 2,and the connectivity κ(G) ≥ 3 if γ≥ 3,κ(G) ≥ 4 but g(G) 6 if γ = 2,(4) Δis sufficiently larger than a given number only depending on γ,then χγ(G) ≤ M- 1.By means of the spectral radius λ1(G) of the adjacency matrix of G,it was shown that χ2(G) ≤λ1(G)2+ 1,where the equality holds if and only if G is a star or a Moore graph with diameter 2 and girth 5,and χγ(G)λ1(G)γ+1 ifγ≥3. 相似文献