X射线荧光光谱法测定增产丙烯助剂中磷和铁的研究

使用X射线荧光光谱仪,采用人工合成标样,设计合成了一套标准样品,采用数学校正法中的经验系数法校正元素间的互相干扰,样品不经任何处理,粉末直接压片,经验系数法校正基体效应,建立了分析测定增产丙烯助剂中磷和铁含量的方法。讨论了样品制作方法,合适的测量条件,探讨了试样中元素间的相互影响。实验结果表明,该方法重现性好,准确度和精密度较高,测定磷和铁的相对标准偏差为：0.34%和0.59%;测定范围磷为0.01%～2.5%,铁为0.01%～2.5%。分析结果与化学法、等离子发射光谱法测定结果吻合。该方法快速、简便,样品处理简单,可以不分解;分析速度远快于其他分析方法,结果准确,单次测量一个样品只需要5 min,适用范围广,满足了科研和工业生产的需要。     

Terahertz emission in tenuous gases irradiated by ultrashort laser pulses

Mechanism of terahertz (THz) pulse generation in gases irradiated by ultrashort laser pulses is investigated theoretically. Quasi-static transverse currents produced by laser field ionization of gases and the longitudinal modulation in formed plasmas are responsible for the THz emission at the electron plasma frequency, as demonstrated by particle-in-cell simulations including field ionization. The THz field amplitude scaling with the laser amplitude within a large range is also discussed.     

Octet baryon masses with two-gluon exchange effect

We report our investigation on the octet baryon spectrum in the nonrelativistic quark model by taking into account the two-gluon exchange effect. The calculated octet baryon masses agree better with the experimental data. It is also shown that the two-gluon exchange interactions bring a significant correction to the Gell-Mann-Okubo mass formula.     

空气中痕量铀的现场光度法测定

作为一种天然放射性金属元素,铀及其化合物可以地气为分散系,以气溶胶形式稳定存在并随空气迁移。气相中铀可经多种途径对人体造成放射性危害,而其浓度变化与该区域核能开发与利用有关。因此,对空气中铀的快速现场检测具有现实意义。采用普通气泵对低品位铀矿石上方的空气进行采样,并以2.0 mol·L-1硝酸溶液对气体进行吸收,向溶液中添加固体试剂包,对溶液中微量铀进行显色后以手持式光度计进行现场光度分析。结果表明：对于普通低品位铀矿石样品,空气中铀含量可用本方法检出,该方法多次测定的RSD为1.72%,其结果与ICP-MS分析结果一致。将该方法用于区分铀矿石和其他矿石,具有成本低廉,操作方便,结果准确可靠等优点。     

Sequential over-barrier ionization of multi-electron atoms in the tens-to-hundreds keV/u energy range

Our previous work on the classical over-barrier ionization model for helium double ionization is extended to the complex multi-electron system of Ne.The total and q-fold ionization cross sections are calculated at energies ranging from a few tens to several hundred keV/u.The calculation results are in good agreement with the experimental data,and the energy dependence of the cross sections suggests that the multi-ionization of a strong perturbated complex atom is probably the sequential over-barrier ionization process.     

电场中Eu原子电离阈移动的实验研究

提出了一种新方法, 精确确定了稀土Eu原子第一电离阈的位置. 先用脉冲电场对Eu原子的高激发Rydberg态进行延时场电离探测, 再通过反向静电场排除光电离和自电离等其他路径所产生的离子信号的干扰, 观察并研究了Eu原子第一电离阈随着电场移动的规律. 由此所确定的零场下第一电离阈的数值与采用其他方法所确定的文献值^{[1, 2]}相一致, 从而验证了该方法的可靠性.     

有效质量差异和电场对GaN/AlxGa1-xN球形量子点电子结构的影响

用平面波展开法对GaN/Al_xGa_1-xN球形量子点中类氢杂质态能级随量子点半径、Al组分以及结合能随Al组分的变化规律进行了详细讨论.计算了量子点内外有效质量差异对杂质态能级和结合能的修正,结果表明对于Al组分较高的GaN/Al_xGa_1-xN球形量子点,电子有效质量差异对杂质能级和结合能的修正不能忽略.考虑电子有效质量差异后,进一步具体计算了杂质结合能随量子点半 关键词： 球形量子点 平面波展开法 有效质量     

Calculated cross sections for the single ionization of atoms (N, Cu, As, Se, Sn, Sb, Te, I, Pb) by electron impact

By correcting some primary parameters in the semi-classical Deutsch--M?rk (DM) formula, this paper calculates the absolute single electron-impact ionization cross sections of atoms N, Cu, As, Se, Sn, Sb, Te, I and Pb from threshold to 10000eV. The calculated cross sections are compared with available experimental data and other theoretical results. An excellent agreement was achieved between the calculated and measured cross sections for these atoms over a wide range of impact energies.     

对23P2介子九重态中同位旋标量成员的质量分析

基于实验上已经确认的基态张量介子九重态的安排和现有的实验数据,利用从雷吉轨迹理论和质量混合矩阵推导出的介子质量关系,对张量介子第一径向激发态的安排做了分析预测.根据得到的结果,可以推测f₂（1810）和f₂（2010）可能作为张量介子第一径向激发态的候选者.同时给出了f₂（1810）和f₂（2010）作为张量介子第一径向激发态时的衰变信息.这些结论对激发态张量介子,特别是其中的同位旋标量态的安排将提供帮助.