共查询到20条相似文献,搜索用时 187 毫秒
1.
本文报道了用激光选择性探测少数约原子的共振双光子电离实验,铯原子的光电离达到了完全饱和,每一个激光脉冲探测到的原子数为5.3×10~4。使用一台可调频染料激光器完成了铯原子的共振双光子电离,第一个光子使Cs原子从基态6~2S_(1/2)激发到7~2P_(1/2)能级,第二个光子使Cs原子离化。本实验采用自建的消融灯泵浦的脉冲染料激光强迫振荡器,输出线宽为0.5(?),波长4593(?),能量为300mJ,脉宽2μs,激光束被聚焦到原子束池中,能量密度始终保持大于1J/cm~2,电离后的离子电子对由静电计检测。为了与实验值比较,假设对一个简易的计算模型进行了理论计算,实验值与理论值很好地符合。 相似文献
2.
研究电弱统一标准模型(W-S)里的电磁相互作用,传递相互作用的是 光子传播子,并对光子传播子里的“树图”以及出现轻子与夸克混合圈中的“链圈图”及其“链图”作了考察与分析,获得光子重整化链图传播子函数 “精确”解析计算结果. 利用这一结果,又对高能物理中备受关注的一类轻子反应: 作了有关研究,计算出在光子链图传播下的反应截面,并获得“精确”理论计算结果,同时还与实验结果作了对比分析,发现本文理论计算结果与实验吻合较好,获得了有关“辐射修正”的许多重要分析结果。 相似文献
3.
W-S中含Fermi圈的光子链传播子及其e-e+→μ-μ+截面 总被引:1,自引:0,他引:1
研究电弱统一标准模型(W-S)里的电磁相互作用,传递相互作用的是γ,光子传播子,并对光子传播子里的"树图"以及出现轻子与夸克混合圈中的"链圈图"及其"链图"作了考察与分析,获得光子重整化链图传播予函数"精确"解析计算结果.利用这一结果,又对高能物理中备受关注的一类轻子反应:e-e →μ-μ 作了有关研究,计算出在光子链图传播下的反应截面,并获得"精确"理论计算结果,同时还与实验结果作了对比分析,发现本文理论计算结果与实验吻合较好,获得了有关"辐射修正"的许多重要分析结果. 相似文献
4.
计算了由准相干双光子相互作用导致的低横动量双轻子产生。 对于不同的质量范围, 准相干双光子相互作用在低横动量区域都很重要。 将计算结果与相对论重离子对撞机RHIC的PHENIX实验数据进行比较, 发现随着双轻子不变质量的增加, 准相干双光子过程的修正作用会更加明显。 相似文献
5.
本文提出共振双光子吸收光谱的一种新的实验方法.实验装置与双光子荧光法测超短脉冲脉宽的装置是一样的.在测定了信号强度的反差比以后可以推知完全共振双光子吸收截面与两步单光子吸收截面之比值.理论计算表明,本方法的适用范围是相当大的. 相似文献
6.
7.
在入射光子能量为79.6 eV~139 eV范围内,利用DS3C模型计算了不同碰撞几何条件下He光双电离的三重微分截面(TDCS),并与3C模型计算结果、CCC理论结果和实验数据做了比较.表明,末态波函数动量相关效应成功地修正了3C结果,特别当入射光子能量接近阈值时,明显改善了与实验结果的符合程度. 相似文献
8.
应用双中心的原子轨道强耦合方法研究了He2+-He碰撞中的电荷转移过程,计算了随入射离子能量变化的单电子俘获总截面及各个次壳层的态选择截面,并与其它理论结果和实验结果进行了比较,发现我们的理论结果与实验很好的符合.针对中国科学院近代物理研究所最近的实验测量,我们也计算了电荷转移过程的微分截面. 相似文献
9.
10.
11.
在不可约张量法基础上,利用二次量子化方法计算了原子的双光子激发截面.作为一个实例,计算了Hg原子的双光子激发截面.理论结果与实验结果在数量级上有较好的符合. 相似文献
12.
13.
The Stark shifts and widths of the highly excited states near the classical ionization threshold of a hydrogen atom are calculated by the B spline technique plus complex scaling method. The Lanczos method has been used in our calculations and is proved to be powerful. Our results are in agreement with the experimental results and theoretical ones obtained by other methods. The method can also be used to calculate the same problem for atoms in parallel and cross electric and magnetic fields. 相似文献
14.
We develop an approximate model for the process of direct (nonsequential) two-photon double ionization of atoms. Employing the model, we calculate (generalized) total cross sections as well as energy-resolved differential cross sections of helium for photon energies ranging from 39 to 54 eV. A comparison with results of ab initio calculations reveals that the agreement is at a quantitative level. We thus demonstrate that this complex ionization process can be described by the simple model, providing insight into the underlying physical mechanism. Finally, we use the model to calculate generalized cross sections for the two-photon double ionization of neon in the nonsequential regime. 相似文献
15.
16.
17.
A new Coulomb distorted-wave method with coupled-channel target functions is used to calculate total ionization cross-sections for helium in positron collisions. Besides Slater-like orbitals we use regular Coulomb wave packets in our configurational interaction basis to describe the target continuum. The incident positron energy was varied between the ionization threshold and 500 a.u. The results are in good agreement with experimental data and other theoretical calculations. Comparing to other sophisticated distorted wave methods our model is much easier to implement and gives accurate results. As a new feature we present ionization cross-sections where the He + ion remains in the 1s ground state or excited to the 2s or 2p state. As we know there are no experimental work done to determine such cross-sections. In the case of ionization followed by 2s or 2p excitation we compared our results with other calculations.Received: 18 February 2004, Published online: 15 April 2004PACS:
34.85. + x Positron scattering 相似文献
18.
A time-dependent close-coupling method is used to calculate, for the first time, fully differential cross sections for the complete fragmentation of helium by two photons. Surprising differences in the magnitude of the total-integral cross sections are found in comparisons with other calculations. These differences are found to be due to a core-excited resonance enhancement of the two-photon process for both single and double ionization. These calculations provide theoretical support for ground-breaking measurements expected to be obtained from free-electron laser experiments in the near future. 相似文献
19.
Highly selective population of two excited states [2mm]in nonresonant two-photon absorption 下载免费PDF全文
A nonresonant two-photon absorption process can be manipulated by tailoring the ultra-short laser pulse. In this paper, we theoretically demonstrate a highly selective population of two excited states in the nonresonant two-photon absorption process by rationally designing a spectral phase distribution. Our results show that one excited state is maximally populated while the other state population is widely tunable from zero to the maximum value. We believe that the theoretical results may play an important role in the selective population of a more complex nonlinear process comprising nonresonant two-photon absorption, such as resonance-mediated (2+1)-three-photon absorption and (2+1)-resonant multiphoton ionization. 相似文献
20.
基于多组态Dirc-Fock方法和密度矩阵理论,给出了原子序列双光双电离光电子角分布的计算表达式,发展了相应的计算程序.利用该程序对Ar原子3p壳层序列双光双电离过程进行了理论研究,给出了光电离的总截面、磁截面、剩余离子取向以及光电子角分布的各向异性参数与入射光子能量的函数关系.结果显示在光电离截面的Cooper极小位置附近取向参数出现极大值,而光电子角分布的各向异性参数在该位置附近出现极小值.进一步给出了33.94和55.34 eV光子能量下序列双光双电离过程中第一步的Ar原子和第二步的Ar^+离子3p壳层光电子角分布,分析了序列双光双电离光电子角分布与单光电离光电子角分布的差异.将计算结果与文献已有的数据进行了比较,具有很好的一致性.本文的研究结果对揭示光与物质相互作用的非线性动力学机制具有重要的参考价值. 相似文献