双δ掺杂In_(0.65)Ga_(0.35)As/In_(0.52)Al_(0.48)As赝型高迁移率晶体管材料子带电子特性研究

研究了基于InP基的In_(0.65)Ga_(0.35)As/In_(0.52)Al_(0.48)As赝型高迁移率晶体管材料中纵向磁电阻的Shubniko-de Haas (SdH)振荡效应和霍耳效应,通过对纵向磁电阻SdH振荡的快速傅里叶变换分析,获得了各子带电子的浓度,并因此求得了各子带能级相对于费米能级的位置.联立求解Schrodinger方程和Poisson方程,自洽计算了样品的导带形状、载流子浓度分布以及各子带能级和费米能级位置.理论计算和实验结果很好符合.实验和理论计算均表明,势垒层的掺杂电子几乎全部转移到了量子阱中,转移率在95%以上.

激发态~(17)Ne双质子2p发射的实验

<正>在中国科学院近代物理研究所放射性束流装置RIBLL上完成了17Ne+197Au的实验,采用硅条探测器与CsI(Tl)+PIN探测器阵列进行运动学完全测量,研究了17Ne双质子发射的机制。实验选用

稀有事件搜索

简单介绍了远离核奇异性质研究的科学意义,报道了稀有事件的搜索方法,以高生成额、高分离效率和高探测效率的方法搜索稀有事件。通过放射化学分离方法从天然Th中提取出镭元素,准备薄的228Raβ→-228Ac源。由60MeV/u18O离子照射天然Th靶引起的232Th-2p反应产生230Ra,通过放射化学分离方法从被照射的靶中提取出镭元素并制成薄源,经230Raβ→-230Ac得到230Ac。利用35MeV的质子束轰击ThO2粉末靶,通过232Th(p,3n)反应产生230Pa核,经用放射化学分离方法分离出Pa,并制成230Paβ→-230U测量源。用固体径迹探测器和PHGe"射线探测器记录和测量来自源中的裂变碎片(重离子)和"谱,观测到它们的!延发裂变或重离子事件,得到228Ac和230Ac的!延发裂变概率分别为(5±2)×10-12和(1.19±0.85)×10-8,230U发射22Ne相当于α衰变的分支比B=$Ne/$#为(1.3±0.8)×10-14。

Two-electron-one-photon M1 and E2 transitions between the states of the 2p(3) and 2s(2)2p odd configurations for B-like ions with 18 <= Z <= 92

Two-electron-one-photon (TEOP) M1 and E2 transition energies, line strengths and transition probabilities between the states of the 2p(3) and 2s(2)2p odd configurations for B-like ions with 18 <= Z <= 92 have been calculated using the GRASP2K package based on the multiconfiguration Dirac-Hartree-Fock (MCDHF) method. Employing active-space techniques to expand the configuration list, we have systematically considered the valence, core-valence and core-core electron correlation effects. Breit interaction and quantum electrodynamical (QED) effects were also included to correct atomic state wavefunctions and the corresponding energies. Influences of electron correlation, Breit interaction and QED effects on transition energies and line strengths of the TEOP M1 and E2 transitions were analysed in detail. The present results were also compared with other theoretical and experimental values.

溶胶-凝胶法制备纳米Pb(Zr_(0.52)Ti_(0.48))O_3

以醋酸铅 ,硝酸氧锆 ,钛酸四丁酯为原料用溶胶 -凝胶法制备了纳米 Pb( Zr0 .52 Ti0 .48) O3 ( PZT)。结果表明 ,随溶剂中乙二醇单甲醚与水的比例的增大 ,PZT粉体的晶化温度增高 ,晶粒的粒径尺寸也增大 ,当V( C3 H8O2 ) / V( H2 O) =4 .4 7时 ,不仅凝胶完成时间短 ,且可得到粒度分布集中、晶化温度低的 PZT粉体。用原子力显微镜测定 PZT的粒径为 6 0～ 70 nm,用 TG-DTA分析确定在 4 43℃即可发生晶化反应 ,在 5 0 0℃下结晶完善。通过对不同温度下热处理的粉体的红外光谱和 X射线衍射的分析 ,对溶胶 -凝胶法制备 PZT粉体形成钙钛矿结构的过程进行了研究。

Ciclo I de seleção na população de milho CMS 52 nos tabuleiros costeiros do nordeste brasileiro.

1998

Ciclo II de seleção na população de milho CMS 52 no nordeste brasileiro.

1998

Practice Links [Issue 52, April 2013]

Practice Links is a free e-publication for practitioners working in Irish social services, voluntary and nongovernmental sectors. Practice Links was created to enable practitioners to keep up-to-date with new publications, electronic resources and conference opportunities. Issue 52 contains reviews on publications covering Irish adoption stories, hospital to home discharge planning, cyber technology for social workers and meeting the service needs of young care-leavers.

The electron impact ionization of magnesium (2p)

A systematic study of the triple differential cross section for the electron impact ionization of magnesium is presented. Complete sets of theoretical results using both the first Born and the distorted wave Bom approximation are given for a range of asymmetric kinematical regimes. How the physical significance of the different approximations enter the character of the cross sections will be explicitly demonstrated. Comparison is made with experiments of the Maryland group and suggestions are made for new experiments.

Negative photoion spectroscopy of freon molecules in the vicinity of the Cl 2p edge

Polar photodissociation of CFnCl4-n (n=0-2) has been studied using synchrotron radiation within the energy range 195-217 eV. The first observations of negative photoion fragments from these molecules after core excitation are reported. In addition to observing a number of previously known resonances two additional resonant states, just above the Cl 2p ionization limit, are observed and play an important role in the polar photodissociation process. The difficulties in identifying these above threshold spin-split features using negative photoion spectroscopy are discussed.