首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 281 毫秒
1.
Frederick Calvin Brown (1924–2011) pioneered soft X-ray science and enabling instrumentation. A personal recollection is here presented [1 I was called by Herman Winick, who apologized for not having contacted me earlier, about providing a personal recollection on the first years at SSRP and asking if I could submit a note. And, by the way, the submission was needed in two weeks. [Google Scholar]] of the story of two worlds in 1973–1975, in which Fred led the initiative which created the foundation for significant scientific contributions enabled by new instrumentation. One world was the industrial sponsorship by the Xerox Palo Alto Research Center under the leadership of Dr. George Pake of our research group in the General Science Lab and the funding, in the other world, of the development at the Stanford Synchrotron Research Project of the 4° Beamline, the world's first dedicated synchrotron source for Soft X-ray Science.  相似文献   

2.
First, two tanh-coth type solutions of a class of nonlinear wave equation are derived by using a simplified modified extended tanh-function method. Then, further analysis to some tanh-coth type solutions of nonlinear evolution equations are given. The results show that when balance number m is one or two, the tanh-eoth type solutions obtained by the modified extended tanh-funetion method can be obtained by using the hyperbolic-function method.  相似文献   

3.
The effects of the Dzyaloshinski-Moriya (DM) interaction on the ground-state properties of the anisotropic XY chain in a transverse field have been studied by means of correlation functions and entanglement. Different from the case without the DM interaction, the excitation spectra εk of this model are not symmetrical in the momentum space and are not always positive. As a result, besides the ferromagnetic (FM) and the paramagnetic (PM) phases, a gapless chiral phase is induced. In the chiral phase, the von Neumann entropy is proportional to log2L (L is the length of a subchain) with the coefficient A ≈ 1/3, which is the same as that of the XY chain in a transverse field without the DM interaction for γ = 0 and 0 h ≤ 1. And in the vicinity of the critical point between the chiral phase and the FM (or PM) phase, the behaviors of the nearest-neighbor concurrence and its derivative are like those for the anisotropy transition.  相似文献   

4.
H4+的稳定性及形成和分解过程实验研究   总被引:3,自引:1,他引:2  
利用Penning ion trap获得了七种不同延时时间(即反应时间)的离子谱Hn+(n≤4),用充分的实验数据证实了H4+是稳定的,稳定时间达1秒量级。实验结果显示:H4+是经合成反应H2++H2→H4+,H3++H+H2→H4++H2产生的;H4+的分解产物是H3++H。分析得出:H4+构型为H3+-核构型。  相似文献   

5.
Under the condition of an equal mixing of vector and scalar potentials, exact solutions of bound states of the Klein-Gordon equation with pseudo-Coulomb potential plus a new ring-shaped potential are presented. Simultaneously, energy spectrum equations are also obtained. It is shown that the radial equation and angular wave functions are expressed by confluent hypergeogetric and hypergeogetric functions respectively.  相似文献   

6.
逮怀新 《大学物理》1997,16(1):9-12
把耦合项为C(a^1a2^+a2^+a1)+D(a^+1a+2+a2a1)的Hamilton量写成超矩阵相乘的形式,通过正则变换使其对角化。  相似文献   

7.
A kind of hybrid device for acoustic noise reduction and vibration energy harvesting based on the silicon micro- perforated panel (MPP) resonant structure is investigated in the article. The critical parts of the device include MPP and energy harvesting membranes. They are all fabricated by means of silicon micro-electro-mechanical systems (MEMS) tech- nology. The silicon MPP has dense and accurate micro-holes. This noise reduction structure has the advantages of wide band and higher absorption coefficients. The vibration energy harvesting part is formed by square piezoelectric membranes arranged in rows. ZnO material is used as it has a good compatibility with the fabrication process. The MPP, piezo- electric membranes, and metal bracket are assembled into a hybrid device with multifunctions. The device exhibits good performances of acoustic noise absorption and acoustic-electric conversion. Its maximum open circuit voltage achieves 69.41 mV.  相似文献   

8.
许武  张新夷 《发光学报》1983,4(4):14-22
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。  相似文献   

9.
We study the properties of two-mode phase operator √(a++b)/(a+b+) and the phase state by constructing the number-difference orthonormal state |q, г). We prove that |q, г ) constitutes a complete and orthonormal representation (number-difference representation). We show that two-mode phase operator √(a++b)/(a+b+) exhibits its phase behavior explicitly in the number-difference representation, which resembles the single-mode phase operator e ≡ (1/√a+a+1)a. The corresponding phase state is also studied.  相似文献   

10.
Hiroyuki Kamano 《中国物理 C》2009,33(12):1077-1084
We present an overview of a research program for the excited nucleon states in Excited Baryon Analysis Center (EBAC) at Jefferson Lab. Current status of our analysis of the meson production reactions based on the unitary dynamical coupled-channels model is summarized, and the N* pole positions extracted from the constructed scattering amplitudes are presented. Our plans for future developments are also discussed.  相似文献   

11.
在改变MS结势垒区宽度的同时,我们测量了在ZnSe:Mn2+晶体、ZnS:Er3+和ZnS:Sm3+薄膜中的Mn2+、RE3+特征谱的电致发光衰减.测量了高阻和低阻ZnS:Mn2+在变化温度(77K—500K)时,Mn2+发光强度的改变.认为在室温以下,Mn2+和RE3+在低阻ZnS和ZnSe中的辐射跃迁均受到Auger猝灭的影响.  相似文献   

12.
氟化物中Yb3+对Ho3+, Tm3+的直接敏化上转换作用   总被引:5,自引:0,他引:5  
采用双掺杂(Yb^3 /Ho^3 )和多掺杂(Ho^3 /Yb^3 /Tm^3 )方式,研究了氟化物中Yb^3 对Ho^3 ,Tm^3 的直接敏化上转换作用,并对它们在980nm激光激发下的上转换光谱特性进行了比较,对它们的上转换机理作了详细的讨论分析。观测到两处很强的上转换发光,分别是Yb^3 /Ho^3 共掺杂体系中^5F4^5S2(Ho^3 )→^5Is(Ho^3 )的荧光跃迁和Ho^3 /Yb^3 /Tm^3 共掺杂体系中^3H4(Tm^3 )→H6(Tm^3 )的荧光跃迁。还发现由于添加了Tm^3 ,减弱了Yb^3 /Ho^3 共掺杂体系中Ho^3 在可见光范围的上转换发光强度。  相似文献   

13.
郑建宣  张文英  余锦堂 《物理学报》1965,21(7):1456-1460
用X射线方法测定了银-锡-铝三元系合金相图。合金含量从30wt.%Sn到纯锡,从30wt.%Al到纯铝。同时,对此三元系的富银角(<30wt.%Sn,<30wt.%Al)相图的γ相区,ζ+δ相区和β+γ+δ相区重新做了测定。室温相截面由六个单相(即α,μ,β,γ,Sn和δ)相区,八个双相(即α+μ,α+β,β+μ,β+γ,γ+Sn,β+Sn,β+δ及Sn+δ)相区,和三个三相(即α+β+μ,β+γ+Sn及β+Sn+δ)相区所构成。所有单相与三个二元系的单相一致,没有新相出现。  相似文献   

14.
YU  Ya-Xuan 《理论物理通讯》2009,(10):637-640
In this paper exact solutions of a new modified nonlinearly dispersive equation (simply called inK(m, n, a, b) Ua Ub equation), u^m-1 ut + α( u^n)x +β(u^a(u^b)xx)x = 0, is investigated by using some direct algorithms. As a result, abundant new compacton solutions (solitons with the absence of infinite wings) and solitary pattern solutions (having infinite slopes or cusps) are obtained.  相似文献   

15.
本文在准一维紧束缚近似下,研究了孤子中的再激发。得到 , ,, , , 。其中 , 和 分别代表中性孤子、带电孤子和带电极化子, 表示链中出现的扭结。  相似文献   

16.
Ba2SiO4荧光粉中Ce3+和Eu2+的光谱性质和能量传递   总被引:5,自引:4,他引:1  
采用高温固相法合成了绿色荧光粉Ba2SiO4:Ce3 ,Eu2 .测量了它们的吸收光谱、激发光谱和发射光谱,观察到了Ba2SiO4中Ce3 对Eu2 发光的敏化现象,发光的敏化作用缘于Ce3 和Eu2 之间的高效无辐射能量传递.  相似文献   

17.
邹冰松 《中国物理 C》2009,33(12):1113-1119
Complementary to the conventional experimental studies on N* from πN and γ(*)N reactions, the e+e-, pp and pp collisions can give novel insights into these N* resonances. While the e+e- collisions through production and decay of vector charmonium ψ provide a nice isospin filter for a simultaneously study of N*, △*, ∧*, ∑* and 2*, the pp collisions should be the best place for producing those △*++ with large coupling to p+p though pp →nA*++ reaction, and the pp collisions should be the best place for looking for those N* with large coupling to σN.  相似文献   

18.
利用高温固相反应法合成了Eu^3+掺杂的MCeO3(M=Sr,Ba)发光粉末样品,采用X射线衍射技术和荧光光谱等测试手段分别对其物相组成和发光性质进行了研究。X射线衍射结果显示,Eu^3+离子容易替代MCeO3晶格中M^2+离子的位置。荧光光谱测试结果表明,Eu^3+掺杂的SrCeO3和BaCeO3样品在紫外波段存在着非常宽的吸收带,峰值分别位于311和320nm左右,它们属于Ce^4+-O^2-的电荷迁移带,SrCeO3和BaCeO3基质与Eu^3+离子之间存在着能量转移。在MCeO3:Eu^3+样品中,Eu^3+的发射主要来自于^5D0激发态能级,其中以磁偶极跃迁^5D0-^7F1发射强度为最大;此外样品中还存在着较高的^5D1激发态能级的辐射跃迁。SrCe03:EU^3+样品的发射强度远大于BaCeO3:EU^3+样品。  相似文献   

19.
本文研究了单掺(Sm~(3+),Ce~(3+)、Gd~(3+).Sb~(3+)、双掺(Sm~(3+)+Ce~(3+)、Sm~(3+)+Gd~(3+),Sm~(3+)+Sb~(3+))和兰掺(Sm~(3+)+Gd~(3+)+Ce~(3+))约四十余种不同玻璃的发射谱和激发谱.探讨了玻璃成份和掺杂离子浓度对Sm~(3+)发光性质的影响以及Ce~(3+),Gd~(3+)、Sb~(3+)、Ce~(3+)+Gd~(3+)对Sm~(3+)的敏化作用。  相似文献   

20.
In this work, we designed and synthesized a novel quinolin-based derivative which exhibited signaling behaviors for Cu2+. Upon the addition of Cu2+ to the solution of the molecule, it displayed an obvious fluorescence quenching in a linear fashion due to the formation of a 1:1 metal–ligand complex. This fluorescent sensor exhibited a rare sensitivity toward Cu(II) (the level of magnitude could be 6?×?10?8), a rapid response (<10 s) and also high selectivity toward Cu2+ over other metal ions such as Na+, K+, Ca2+, Mg2+, Ba2+, Fe3+, Mn2+, Hg2+, Pb2+, Cd2+, Cr3+, Co2+, Zn2+ and Al3+. Simultaneously, the cell imaging experiments and filter paper test demonstrated its extensive applicability.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号