激光场中极化势对电子-氦原子散射影响

构建含有极化势的静电屏蔽势和单纯的静电屏蔽势这两种原子势模型,应用第二玻恩近似(SBA)理论,分别对激光场中电子-氰原子散射截面进行了理论计算.对比实验结果发现含有极化势的静电屏蔽势给出的结果与实验符合较好.表明极化势在激光辅助电子-原子散射中起着重要作用.     

激光场中极化势对电子-氦原子散射影响

构建含有极化势的静电屏蔽势和单纯的静电屏蔽势这两种原子势模型,应用第二玻恩近似（SBA）理论,分别对激光场中电子-氦原子散射截面进行了理论计算。对比实验结果发现含有极化势的静电屏蔽势给出的结果与实验符合较好。表明极化势在激光辅助电子-原子散射中起着重要作用。     

双模激光场中电子-原子散射

在一阶玻恩近似的基础之上,本文首次在激光场的极化方向平行于入射电子的方向这种散射模式下,应用二阶玻恩近似理论对双模激光场中电子-氩原子散射的自由-自由跃迁过程进行了研究,并与一阶玻恩近似结果进行比较.结果表明,二阶玻恩近似理论在多模激光场中的应用也是比较成功的.     

激光辅助电子-原子碰撞K-W公式与第二玻恩近似

最近的CO₂激光辅助电子-原子碰撞的测量结果与K-W公式存在着非常大的差异,用玻恩近似理论对此进行了详细的研究.结果表明第二玻恩近似结果与实验结果符合得比较好,K-W公式的预言只相当于第一玻恩近似.同时,计算表明电子-原子间的极化势在激光辅助电子-原子散射过程中起着重要的作用. 关键词：     

激光辅助电子-原子碰撞 K-W公式与第二玻恩近似

最近的 Ｃ Ｏ２ 激光辅助电子原子碰撞的测量结果与 Ｋ Ｗ 公式存在着非常大的差异,用玻恩近似理论对此进行了详细的研究．结果表明第二玻恩近似结果与实验结果符合得比较好, Ｋ Ｗ 公式的预言只相当于第一玻恩近似．同时,计算表明电子原子间的极化势在激光辅助电子原子散射过程中起着重要的作用．     

相互作用势对激光辅助电子-氩原子散射的影响

在三种势模型下运用二级玻恩近似理论计算了电子与氩原子散射的微分散射截面. 结果显示这些势模型在激光辅助电子-氩原子散射系统中的运用非常成功. 另外,分析和讨论了静电势、交换势和极化势对散射截面的影响.     

多模激光场中电子-原子散射

利用微扰理论对多模激光场中电子-原子散射进行了初步研究. 在激光场的极化方向平行于入射电子方向这种特殊的散射模式下, 计算得到了电子-原子微分散射截面与激光场的相移、交换光子数之间的关系. 结论和其它相关理论是一致的.     

激光场中电子自由—自由跃迁吸收截面

导出了激光场中电子被中心势场散射的以分波相移表示的自由-自由跃迁吸收截面理论计算公式,以激光场中慢电子被He原子势场散射为例做了计算,说明对于自由-自由吸收截面,该公式的计算是有效的、方便的。     

圆极化激光场中e-He散射

把二级玻恩近似(SBA)的方法推广至圆极化激光场,计算了发生多光子交换时的激光辅助电子被氦原子散射的微分散射截面。对计算结果进行了分析,并与线性极化激光辅助散射结果进行了比较。     

离子极化势对钙原子共面对称(e,2e)反应影响的数值研究

本文使用扭曲波波恩近似方法(DWBA)研究了共面对称条件下钙原子的电子碰撞电离反应((e,2e)反应),在DWBA理论的基础上,考虑了原子极化势和离子极化势对三重微分散射截面的影响.采用发展的DWBA方法,我们研究了出射电子能量从6.75 e V到29.25 e V范围内电子与钙原子的碰撞电离过程,计算了电离三重微分截面.通过与已有理论和实验数据进行比较发现,离子极化势对钙原子的共面对称(e,2e)反应散射微分截面有较大的影响,很好的描述了碰撞电离微分截面的结构效应,特别是在散射角度较小时(≦60o),本文计算结果与实验测量非常一致.     

Electron-Helium Scattering in a Bichromatic Laser Field in the Second-Order Born Approximation

The elastic scattering of electrons in atomic helium assisted by a bichromatic laser field is investigated in the second order Born approximation. The target atom is approximated by a simple screening potential. The dependence of the differential cross section on the relative phase between the two laser components is calculated, and compared with the recent results of first order Born approximation [Sun J F, Liang M C and Zhu Z L 2007 Chin. Phys. Lett. 24 2572].     

Static potential renormalization in time-dependent fields

We consider the scattering of electrons at a static potential under the influence of an additional time-dependent, homogeneous electric field (‘microwave’). Starting from a plane wave basis, we derive a generalization of the Born (first) order approximation in arbitrary strong oscillating fields. As an example, we evaluate the Friedel density oscillations around a static scatterer whose potential is renormalized by the microwave. The microwave leads to a band of inelastic scattering channels with effective potentials, the shape of which can be ‘tuned’ by the microwave polarization and strength.     

强激光场中H~-离子二维光电子动量谱的理论研究

选用两个模型势,利用强场近似方法研究了H-离子在线性极化强激光场中二维光电子动量谱中次外层后重散射环.研究结果表明:两个模型势中的极化势对二维光电子动量谱的影响很小;随着激光强度的增加,二维光电子动量谱中出现后重散射环的数目变多,沿着次外层后重散射环的光电子的角分布波动性变小,能够通过多项式拟合的方法从二维光电子动量谱中次外层后重散射环获得精确的电子与H原子的弹性散射截面,特别适用于激光强度较小的情况.     

The second Born approximation of electron–argon elastic scattering in a bichromatic laser field

We study the elastic scattering of atomic argon by electron in the presence of a bichromatic laser field in the second Born approximation. The target atom is approximated by a simple screening potential and the continuum states of the impinging and emitting electrons are described as Volkov states. We evaluate the S-matrix elements numerically. The dependence of differential cross-section on the relative phase between the two laser components is presented. The results obtained in the first and second Born approximations are compared and analysed.     

Phase signatures in laser-assisted electron-atom collisions

We study electron-atom scattering in the presence of a laser field with elliptic polarization. We discuss the dependence of the differential cross sections for the cases of circular and linear polarizations as a function of scattering angle. Interesting typical signatures of the phase between the two components of the circular polarization of the laser field appear in the differential cross section.     

Comparison of models for the Gaunt factor for free-free absorption

Within the dipole approximation to the radiation field for the free-free Gaunt factor, we compare various models of the electron-atom (ion) collisional process. These models range in sophistication from the static-exchange to the simple Born, point-charge representation. We also consider a number of local potential models such as the Thomas-Fermi and Free-Electron-Gas. The Born approximation is shown to be singularly unreliable for electron and photon energies between 10 and 100 eV. Of the local potential models, the FEG gives the most accurate results.