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采用金刚石压砧高压装置,研究了双钙态矿结构化合物Sr2FeNbO6及其掺杂物Sr2FeMo0.3Nb0.7O6在室温下,20 GPa内电阻和电容随压力的变化,并发现Sr2FeNbO6在7.5 GPa左右压力下发生了相变,而Sr2FeMo0.3Nb0.7O6的相变发生在2.8 GPa左右。并结合这两个样品的高压下的同步辐射能散X射线衍射实验,进一步证明了这两种相变是电子结构相变引起的。 相似文献
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本文首次研究了Al80Mn14Si6合金在静高压下准晶相得形成。利用静高压熔态淬火方法,在压力2.8和3.1 GPa下得到淬火的Al-Mn-Si样品。电子和X射线衍射实验表明,高压淬火样品中含有准晶二十面体相和非晶相。X射线衍射实验还表明,高压淬火样品经350 ℃退火一小时基本上没有发生变化;而经过500 ℃退火一小时后,准晶相晶化为α-Al73Si10Mn17相。另外,电子衍射实验表明,高压淬火后样品中还存在其它中间亚稳相。本文还讨论了静高压熔态淬火方法的适用性。 相似文献
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采用高分子网络凝胶法,通过控制其化学反应过程,合成了高纯的多晶纳米级粉末Sr2FeMoO6样品A(50 nm)和样品B(100 nm)。对其在高压下的结构稳定性和电学性质进行了研究,并将样品A和样品B的实验结果与已报道的粒度达微米级的块状Sr2FeMoO6样品C的实验结果进行了对比。在实验测量范围内,样品A(50 nm)呈现出最大的体弹模量B0,并在电阻-压力曲线中,电阻下降区域表现出相对较缓的变化率,晶界效应可以用来很好地解释此结果。电学性质测量实验表明,样品在高压下发生了电子结构相变。 相似文献
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本文研究了室温下压力对FexN化合物相分解的影响。X射线衍射分析表明,高压促使氮原子从FexN化合物的晶格中脱溶出来,引起相分解,形成母相与α-Fe。这种相分解现象随压力增大而加强。通过分析不同压力下母相FexN与α-Fe的相对含量,研究了氮从FexN中脱溶的动力学过程,并计算出激活体积。对于Fe3N和Fe4N化合物,其激活体积分别为2.24×10-5 m3/mol和1.62×10-5 m3/mol。本实验还指出,通过对FexN化合物的高压处理以及适当条件下退火,可以获得Fe16N2化合物。 相似文献
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M. Ya. Amusia 《JETP Letters》2009,90(3):161-165
Hartree-Fock atom in a strong electric static field is considered. It is demonstrated that exchange between outer and inner
electrons, taken into account by the so-called Fock term affects strongly the long-range behavior of the inner electron wave
function. As a result, it dramatically increases its probability to be ionized. A simple model is analyzed demonstrating that
the decay probability, compared to the case of a local (Har-tree) atomic potential, increases by many orders of magnitude.
As a result of such increase, the ratio of inner to outer electrons ionization probability became not too small. It is essential
that the effect of exchange upon probability of inner electron ionization by strong electric field is proportional to the
square of the number of outer electrons. It signals that in clusters the inner electron ionization by strong field, the very
fact of which is manifested by e.g. high energy quanta emission, has to be essentially increased as compared to this process
in gaseous atomic objects. 相似文献
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Spatial distribution of high-energy electron emission from water plasmas produced by femtosecond laser pulses 总被引:1,自引:0,他引:1
Li YT Zhang J Sheng ZM Teng H Liang TJ Peng XY Lu X Li YJ Tang XW 《Physical review letters》2003,90(16):165002
High energy electrons emitted by water plasmas produced by a single or a multiple laser pulse are investigated. The multipulse mode greatly enhances the generation and the temperature of hot electrons. Directional emission of high energy electrons over 25 keV is observed in two symmetric directions with respect to the laser axis and at 46 degrees from the directions of the laser electric field. Two-dimensional particle-in-cell simulations reproduce well the experimental results and indicate that the acceleration mechanism of the high energy electrons is due mainly to the resonance absorption at the edge of the spherical droplets formed by the leading pulse. 相似文献
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Cyclotron radiations at an electron cyclotron and its second harmonics frequencies were observed from a turbulently heated plasma in a strong magnetic field. The cyclotron radiations were emitted when the plasma became resistive and the electron temperature was increased. An appreciable effect of an enhanced collision of electrons in the turbulent plasma was observed on the line width. 相似文献
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Heating of plasma electrons by high power millimeter wave fields at cyclotron harmonic resonance is studied. A mirror field is modelled for the local trapping of electrons. It is shown that superthermal electrons can be generated as the consequence of the ECRH of trapped electrons. 相似文献
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利用ESCA-LAB-5电子能谱仪的紫外光电子谱(UPS)和X射线光电子谱(XPS)研究了WC,Pt和W的电子结构,用高灵敏度磁强计在1.5—300K的温度范围内测量了WC和W的磁化率随温度和磁场的变化关系。W的磁化率不随温度变化,遵循Pauli顺磁性规律,而WC则不然,遵循居里定律。根据WC中出现不成对电子自旋磁矩,我们提出假设:WC中由于C的影响,使W的5d电子不再全部共有化,而是像Pt一样,有一部分价电子局域化,这局域化电子的出现,才使WC不同于W,具有“类白金”的催化活性。
关键词: 相似文献
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脉冲流光放电产生的大于等于11.2 eV的高能电子能将处于基态的氮分子激发到N2(C3Πu)态,测试脉冲流光放电时的N2(C3Πu→B3Πg)发射光谱相对强度可以得出脉冲流光放电产生的高能电子的密度。实验在室温常压下研究了空气中线-板式脉冲流光放电脱硫反应器内高能电子密度分布情况,并研究了脉冲电压、反应器的线线间距对反应器内高能电子密度分布的影响。实验结果表明,反应器内的高能电子主要集中在放电线附近高电场区内,随着离放电线的距离增大,高能电子密度减小;脉冲电压对高能电子密度有很大影响,随着电压的升高,高能电子密度基本呈线性增大;线板间距固定,线线间距为线板间距的0.6~1倍时,反应器内高能电子密度分布较为均匀。 相似文献
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Aggarwal MM Ahammed Z Alakhverdyants AV Alekseev I Alford J Anderson BD Anson D Arkhipkin D Averichev GS Balewski J Barnby LS Baumgart S Beavis DR Bellwied R Betancourt MJ Betts RR Bhasin A Bhati AK Bichsel H Bielcik J Bielcikova J Biritz B Bland LC Bonner BE Bouchet J Braidot E Brandin AV Bridgeman A Bruna E Bueltmann S Bunzarov I Burton TP Cai XZ Caines H Calderón de la Barca Sánchez M Catu O Cebra D Cendejas R Cervantes MC Chajecki Z Chaloupka P Chattopadhyay S Chen HF Chen JH Chen JY 《Physical review letters》2010,105(20):202301
The contribution of B meson decays to nonphotonic electrons, which are mainly produced by the semileptonic decays of heavy-flavor mesons, in p + p collisions at √s=200 GeV has been measured using azimuthal correlations between nonphotonic electrons and hadrons. The extracted B decay contribution is approximately 50% at a transverse momentum of pT≥5 GeV/c. These measurements constrain the nuclear modification factor for electrons from B and D meson decays. The result indicates that B meson production in heavy ion collisions is also suppressed at high pT. 相似文献
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利用单电子在固体靶表面准静态电磁场中运动的模型和非线性汤姆孙散射理论,研究了以大角度斜入射的强激光照射在固体靶表面产生的沿靶面方向发射的高能超热电子的运动及其产生的电磁辐射脉冲. 数值模拟表明,靶表面的电子在靶面附近的准静态电磁场和反射的激光场中作振荡. 当电子振荡频率接近激光频率时,电子被有效加速,被加速的电子主要沿靶面方向运动并产生向前的阿秒脉冲辐射. 讨论了电子在加速前的不同初始速度分布对辐射脉冲的时间和空间特性的影响,模拟了不同初始状态的多电子相干辐射脉冲的频谱特性.
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表面准静态电磁场
超热电子
阿秒脉冲
相干辐射 相似文献
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光子与相对论麦克斯韦分布电子散射的描述及能谱角度谱计算非常复杂且费时.本文提出了一种光子与相对论麦克斯韦速度分布电子散射的蒙特卡罗(MC)模拟方法,该方法能够细致模拟高温等离子体中任意能量光子与任意温度电子的Compton和逆Compton散射问题.对于散射后光子的能谱和角度谱参数,可以根据电子温度抽样若干不同状态的电子,分别模拟其与光子发生散射,可以得到各次散射后的光子能量和偏转角度,取统计平均后的结果即可获得该光子与该温度电子散射的能谱和角度谱分布.根据该方法编写了光子与相对论电子散射MC模拟程序,开展了高温全电离等离子体中光子与相对论电子散射的能谱角度谱计算和分析,分析结果显示:热运动电子将展宽出射光子能谱,且低能光子与高温电子散射后的蓝移现象明显;出射光子的角度谱很复杂,其决定于入射光子能量、出射光子能量及电子温度.基于该方法计算并以数表形式给出的光子-相对论电子散射能谱角度谱数据,可以供辐射输运数值模拟程序使用. 相似文献