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1.
报道了利用兰州重离子加速器国家实验室ECR源引出的高电荷态离子207Pbq+(24≤q≤36)入射到Si(110)表面产生的电子发射的实验测量结果.结果表明,高电荷态离子与固体表面相互作用产生的电子发射产额Y与入射离子的电荷态q、入射角度ψ和入射能量E都有很强的关联.首次发现,电子发射产额Y与入射角度ψ间有接近1/tanψ的关系.理论分析认为,这些过程与基于经典过垒模型的势能电子发射过程密切相关.  相似文献   

2.
报道了由兰州ECR源提供的低速高电荷离子40Ar16 入射到云母表面产生的电子发射的实验测量结果.结果发现,电子发射产额Y与离子入射角ψ有近似1/tanψ的关系.基于经典过垒模型,我们对这一关系进行了理论分析.实验结果和理论结果相当符合,这就间接说明势能电子发射是低速高电荷态离子作用于表面发射电子的一个主要途径.  相似文献   

3.
研究了高电荷态离子Arq+(q=16,17,18)入射金属Be,Al,Ni,Mo,Au靶表面产生的X射线谱.实验结果表明,Ar的Kα-X射线是离子在与固体表面相互作用过程中固体表面之下形成空心原子发射的.电子组态1s2的高电荷态Ar16+离子在金属表面中性化过程中,存在的多电子激发过程使Ar16+的K壳层电子激发产生空穴,级联退激发射Ar的Kα 特征X射线.Ar17+离子在金属表面作用过程中产生的X射线谱形与靶材料没有明显的关联,入射离子的Kα-X射线产额与其最初的电子组态有关,靶原子的X射线产额与入射离子的动能有关. 关键词: 高电荷态离子 空心原子 多电子激发 X射线  相似文献   

4.
高电荷态离子126Xeq+与Ti固体表面作用的激发光谱   总被引:1,自引:1,他引:0       下载免费PDF全文
报道用150keV的高电荷态离子126Xeq+(6≤q≤30)轰击Ti固 体表面产生2 00—1000nm波段发射光谱的实验结果.结果显示,用电荷态足够高的离子作光谱激发源,无 需很强的束流强度(nA量级),便可激发起样品表面的原子和离子在可见光波段的特征谱线 .当入射离子剥离度q>qc≈20时,Ti原子及其离子的特征谱线强度突然显著增强 ;不 同金属靶,特征谱线突然增强的qc值不同.理论分析表明,这与q大于此临界值 后,单电子转移释放能量激发靶材料传导电子气体的表面等离激元密切相关. 关键词: 低速高电荷态离子 特征谱线 经典过垒模型 等离激元  相似文献   

5.
实验中测量了0.38V_(Bohr)(460 keV)高电荷态Xe~(q+)(4≤q≤20)离子轰击高纯Ni表面发射的400-510 nm光谱.实验结果包括NiⅠ原子谱线,NiⅡ离子谱线,以及入射离子中性化发射的XeⅠ,XeⅡ和XeⅢ谱线.研究了谱线XeⅡ410.419,XeⅢ430.444,XeⅡ434.200,XeⅡ486.254,NiⅠ498.245,NiⅠ501.697,NiⅠ503.502,NiⅠ505.061和NiⅠ508.293 nm的光子产额随着入射离子电荷态的变化.结果表明,入射离子中性化和溅射Ni原子发射谱线的光子产额随着入射离子电荷态的增加而增加,其趋势与入射离子势能一致.  相似文献   

6.
126Xeq+轰击Al表面产生的原子和离子光谱线   总被引:1,自引:1,他引:0  
报道了高电荷态离子^126Xe^q (6≤q≤30)入射到固体Al表面产生的200~1000nm波段的发射光谱的实验结果。实验表明,在弱束流(nA量级)高电荷态的情况下,通过入射离子与固体靶的相互作用可有效地产生原子和离子的复杂组态间跃迁所形成的可见光波段的特征谱线,而且当入射离子的电荷剥离数超过一临界值后(对Al,q=26),谱线相对强度突然显著增强。根据经典过垒模型COB(The classic over-barrier model),在入射离子的动能较小(~1keV/u)的条件下.高电荷态离子与表面相互作用过程中电子的俘获或转移起着非常重要的作用,通过提高入射离子的电荷态可增强入射离子俘获电子的能力.显著增强激发粒子的光谱线的强度。  相似文献   

7.
报道了在兰州重离子加速器国家实验室电子回旋共振离子源原子物理实验平台上,用高电荷态40Arq+(1≤q≤12)离子作用于半导体Si固体表面时的电子发射产额实验测量.实验中,通过改变炮弹离子的电荷态和引出电压选取其不同的势能和动能,系统地研究了入射离子势能沉积和与其在固体中的电子能损对表面电子发射产额的贡献.结果表明,作为引起表面电子发射的两个主要因素,单离子的电子发射产额与炮弹离子在固体表面的势能沉积和电子能损都有近似的正比关系.  相似文献   

8.
杨兆锐  张小安  徐秋梅  杨治虎 《物理学报》2013,62(4):43401-043401
利用低速(V≈0.01 VBohr)高电荷态Krq+ (q=8, 10, 13, 15, 17)离子轰击金属Al表面, 获得了碰撞过程产生的300–600 nm的光谱. 实验结果表明: 低能大流强(μA/cm2量级)离子束入射金属表面, 可产生溅射原子、离子和入射离子中性化后发射的可见光. 随着入射离子势能(电荷态)增加, 碰撞过程中发射谱线的强度增强. 与激发态3d能级相比, 较高的势能可以有效地激发Al原子的电子到较高4s能级. 关键词: 高电荷态离子 可见光发射 离子与表面作用  相似文献   

9.
用动能一定的高电荷态129Xeq+(17≤q≤27)离子,分别入射洁净的Ta靶表面,测量中性化的激发态Xe原子从组态5p5(23/2) nl退激到组态5p5(23/2) ml’过程中辐射的近红外光谱线.实验结果表明:多激发态的空心原子退激发射其特征光谱线,部分典型的跃迁按照阶梯方式退激.Xe原子发射的谱线的单粒子荧光产额和激发的Ta原子发射谱线的单粒子荧光产额随入射离子电荷态的增加而增加,其增加的趋势与入射离子携带的势能随电荷态增加的趋势一致.证明在近Bohr速度的能区,经典过垒模型是成立的.  相似文献   

10.
用345 keV的Kr15+和340 keV的Kr17+离子以45fi角入射n型GaAs单晶(100)面,测量了表面形貌的变化和发射的375—500 nm Ga I和Kr II的特征光谱线.Krq+(q=15,17)离子轰击后表面形貌的变化主要取决于入射离子的电荷态q.离子沉积到靶表面的能量引起Ga原子激发,其辐射光谱为Ga I 403.2 nm和Ga I 417.0 nm.入射离子中性化过程中俘获GaAs导带电子形成高激发态原子,通过级联退激填充3p,4d等空穴,P壳层电子跃迁发射谱线为Kr II 410.0 nm,Kr II 430.4 nm,Kr II 434.0 nm和Kr II 486.0 nm,Kr II486.0 nm为较强谱线.实验结果表明,入射离子与GaAs单晶相互作用发射的可见光产额与入射离子的电荷态密切相关,较高电荷态Kr17+离子入射产生的光辐射产额大约为Kr15+离子的两倍.  相似文献   

11.
李杰  王育华  董其铮  刘吉地 《中国物理 B》2010,19(6):63301-063301
Y$_{0.75 - x}$GdxAl0.10BO$3:Eu$^{3+}0.10, 0.05R3+ ($R$=Sc, Bi) ($0.00 ≤ x ≤ 0.45$) powder samples are prepared by solid-state reaction and their luminescence properties are investigated. With the replacement of Y3+$ ions by Sc3+$ (or Bi3+)$ and Gd3+$ ions in (Y,Al)BO$3:Eu, the intensities of emission at 254 and 147~nm are remarkably improved, because Sc3+$ ions can absorb UV light and transfer the energy to Eu3+$ ions efficiently. Moreover, Gd3+$ and Bi$^{3 + }$ ions act as an intermediate ``bridge' between the sensitizer and the activator (Eu3+)$ in energy transfer to produce light in the (Y, Gd)BO$3:Bi3+$, Eu3+$ system more effectively. After doping an appropriate concentration of Gd3+$ into Y$_{0.50}$Gd$_{0.25}$Al0.10BO$3:Eu3+_{0.01}$, Bi$^{3+}_{0.05}$, the emission intensity reaches its maximum, which is nearly 110{\%} compared with the red commercial phosphor (Y,Gd)BO$3:Eu and better chromaticity coordinates (0.650, 0.350) are obtained.  相似文献   

12.
解其云  吴小山 《物理学报》2009,58(2):1229-1236
研究了锶空位对La0.7Sr0.3-xxCoO3 (0≤x≤0.2)多晶钴氧化物结构、磁性和输运性质的影响.结果表明:随着锶空位浓度x的增大,A位阳离子无序度增大,导致铁磁双交换作用减弱及反铁磁超交换作用增强,两者相互竞争,出现团簇自旋玻璃态;空位浓度超过10%后,Co—O键长迅速减小,导致晶体场劈裂能加大,大部分三价钴离子以低自旋态出现,系统基态为类超顺磁态, 关键词: 空位掺杂 钴氧化物 自旋转变  相似文献   

13.
The effect of copper doping on charge-orbital ordering in La1/3Ca2/3Mn1 − y Cu y O3 (0 ≤ y ≤ 0.07) is studied by measuring the temperature dependences of the magnetization, the electrical resistivity, and the heat capacity in combination with an electron microscopic investigation of the structure. It is demonstrated that copper doping leads to a lowering of the charge ordering temperature T CO and that this decrease is proportional to the decrease in the Mn3+ ion concentration. In the temperature range 5–300 K, the semiconducting pattern of the electrical resistivity persists for all values of 0 ≤ y ≤ 0.07. Electron microscope studies have shown that the presence of copper suppresses the formation of a regular superstructure, which is characteristic of the undoped starting compound, beginning already from low concentrations (y = 0.01). Differential scanning calorimetry revealed a substantial decrease in the transition entropy at the onset of charge ordering in copper-doped samples as compared to the starting compound. Doping with copper destroys long-range charge-orbital ordering and retains apparently only short-range order. Original Russian Text ? T.S. Orlova, J.Y. Laval, Ph. Monod, V.S. Zakhvalinskiĭ, V.M. Egorov, Yu.P. Stepanov, 2009, published in Fizika Tverdogo Tela, 2009, Vol. 51, No. 1, pp. 91–97.  相似文献   

14.
胡木宏  王治文  曾凡伟  王涛  王晶 《中国物理 B》2011,20(8):83101-083101
The full-core plus correlation method with multi-configuration interaction wave functions is extended to the calcu-lation of the non-relativistic energies of 1s 2 n d (n ≤ 9) states for the lithium isoelectronic sequence from Z=11 to 20.Relativistic and mass-polarization effects on the energy are calculated as the first-order perturbation correction.The quantum-electrodynamics correction is also included.The fine structure splittings are determined from the expectation values of spin-orbit and spin-other-orbit interaction operators in the Pauli-Breit approximation.Combining the term energies of lowly excited states obtained with the quantum defects calculated by the single channel quantum defect theory,each of which is a smooth function of energy and approximated by a weakly varying function of energy,the ion potentials of highly excited states (n ≥ 6) are obtained with the semi-empirical iteration method.The results are compared with experimental data in the literature and found to be closely consistent with the regularity.  相似文献   

15.
肖星星  谢文杰  唐新峰  张清杰 《中国物理 B》2011,20(8):87201-087201
With good electrical properties and an inherently complex crystal structure,Cu 2 x Se is a potential "phonon glass electron crystal" thermoelectric material that has previously not attracted much interest.In this study,Cu 2 x Se (0 ≤ x ≤ 0.25) compounds were synthesized by a melting-quenching method,and then sintered by spark plasma sintering to obtain bulk material.The effect of Cu content on the phase transition and thermoelectric properties of Cu 2 x Se were investigated in the temperature range of 300 K-750 K.The results of X-ray diffraction at room temperature show that Cu 2 x Se compounds possess a cubic structure with a space group of F m3m (#225) when 0.15 < x ≤ 0.25,whereas they adopt a composite of monoclinic and cubic phases when 0 ≤ x ≤ 0.15.The thermoelectric property measurements show that with increasing Cu content,the electrical conductivity decreases,the Seebeck coefficient increases and the thermal conductivity decreases.Due to the relatively good power factor and low thermal conductivity,the nearly stoichiometric Cu 2 Se compound achieves the highest ZT of 0.38 at 750 K.It is expected that the thermoelectric performance can be further optimized by doping appropriate elements and/or via a nanostructuring approach.  相似文献   

16.
Target ionization accompanied with projectile electron loss is investigated for 0.2-7 MeV C^q+ (q = 1 - 4) with He and 0.25-5 MeV O^q+ (q = 1 - 4) with He collisions. For projectile single-electron loss channel, the He double-to-single ionization ratio R is nearly independent of projectile charge state but dependent on the nuclear charge of projectile Zp. The results are analysed with atomic structure qualitatively. So far there have not existed the experimental data comparable with our results, to our knowledge. The ratio R is interpreted in terms of the two-step mechanism. This analysis agrees well with similar experiments in the literature.  相似文献   

17.
Luminescent materials composed of Sr3?x?3y/2MxCeyAlO4F (M=Ca, Ba, 0≤x≤0.9, 0.001≤y≤0.05) were prepared by the solid-state reaction method. X-ray diffraction (XRD) patterns of the obtained oxyfluorides are exhibited for indexing peak positions. Dynamic excitation and emission spectra of the Ce3+-activated oxyfluoride phosphors are clearly monitored. The critical emission quenching as a function of Ce3+ contents in Sr2.5?3y/2M0.5CeyAlO4F phosphors is revealed at quite low concentrations of the activator. CIE coordinates of blue and green Sr2.5?3y/2M0.5CeyAlO4F phosphors are clearly measured. The relative quantum efficiency of Sr2.4985Ca0.5Ce0.005AlO4F based on the integrated emission is determined. The Sr3?x?3y/2MxCeyAlO4F phosphors excited near 410 nm light could be prominent phosphors in applications of NUV-LED.  相似文献   

18.
LnAl3(BO3)4:Eu3+ (Ln=Y, Gd) red phosphor particles were prepared by spray pyrolysis and the luminescent intensity under vacuum ultraviolet (VUV) excitation was investigated by changing Eu3+ content, Y/Gd molar ratio, and boron content. The concentration quenching for Eu3+ activator was observed at 5 at%. The highest luminescent intensity at 615 nm due to the 5D07F2 transitions of Eu3+ was achieved when the ratio of Gd to Y was 0.55. The R/O ratio (obtained by dividing the red emission intensity at 615 nm with the orange one at 592 nm), however, was not influenced by the G/Y ratio. Using excess boron, up to 135% of the stoichiometric quantity, improved the emission intensity of LnAl3(BO3)4:Eu3+ red phosphor. According to XRD analysis, the sample prepared using boron of a stoichiometric quantity had YBO3 phase as a minor phase. Such YBO3 phase progressively disappeared with an increase in the excess quantity of boron, which was responsible for the enhancement of emission intensity. In addition, the R/O ratio became larger and larger by increasing the excess content of boron due to a reduction in the symmetry of Y site. Consequently, both the emission intensity and the color coordinate of LnAl3(BO3)4:Eu3+ red phosphors were successfully optimized in terms of the Y/Gd ratio and the excess quantity of boron in spray pyrolysis.  相似文献   

19.
王菲  王苗苗 《中国物理 B》2011,20(11):113402-113402
Close-coupling calculations are carried out for cross sections of the single electron capture in collisions of Nq+ (q = 5, 6, 7) ions with helium atoms in the collision velocity range from 0.3 a.u. to 1.8 a.u. The relative importances of the single ionization (SI) to the single capture (SC) are investigated for the Nq+ (q = 5, 6, 7) projectiles, respectively. The SI/SC cross section ratio for the N7+ projectile obtained from our calculations is in excellent agreement with the experimental data. The ratio curves also show us distinct behaviours when the charge of the projectile is different. The partial electron capture cross sections for different projectiles indicate that the electron on the target He atom tends to be captured by the projectile into its lower orbital of the outer shell with the decreasing projectile charge.  相似文献   

20.
Ultrafine M5(PO4)3F:Dy3+ (M = Ca, Ba) phosphors were prepared via combustion process using metal nitrates as precursors. The formation of crystalline phosphate was confirmed by X-ray diffraction pattern. The PL excitation spectra show the excitation peaks observed at 250 to 400 nm due to ff transition of Dy3+ ion, which are useful for solid-state lighting purpose (mercury free excitation). The PL emission of Dy3+ ion by 348 nm excitation gave an emission at 489 nm (blue), 582 nm (yellow) and 675 nm (red). All the characteristics of BYR emissions like BGR indicate that Dy doped Ca5(PO4)3F and Ba5(PO4)3F phosphors are good candidates that can be applied in solid-state lighting phosphor (mercury free excited lamp phosphor) and white light LED.   相似文献   

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