Elastic scattering of electrons by metastable hydrogen atoms in the presence of a resonant laser field

Within the framework of the rotating wave approximation the elastic scattering of electrons by metastable 2s state of hydrogen atoms is studied in the presence of a resonant laser field. The frequency of the circularly polarized laser field is chosen to match the 2s-3p transition frequency in the hydrogen atom. Variation of the cross section with laser intensity and with incident electron energy (50-150 eV) is investigated. Received: 18 July 1997 / Received in final form: 5 December 1997 / Accepted: 19 January 1998     

Laser polarization effects on K-shell Compton scattering

We study Compton scattering on the ground state of the hydrogen atom in the presence of an intense low-frequency electric field (the laser) of arbitrary polarization, for incident and scattered photons of energies around 15 keV. The adopted formalism is the nonrelativistic one developed by Voitkiv et al. [J. Phys. B: At. Mol. Opt. Phys. 36, 1907 (2003)] and applied by them for a circularly polarized laser. We explore the spectrum and the electron energy distribution in their dependence on the incident photon energy or electric field intensity, for different polarizations.     

Resonance of exchange amplitude of Compton effect in the circularly polarized laser field

We present, for general relativistic case, a theoretical study of resonance of exchange amplitude when a photon is scattered by an electron in the field of a circularly polarized wave. Resonances are related to a virtual intermediate particle that falls within the mass shell. We find conditions when resonances occur in exchange amplitude. We derive the expressions for the resonant amplitudes and the differential cross-sections when the invariant intensity parameter of the laser field is small (η≪1) and the interference of direct and exchange amplitudes is absent. It is demonstrated that the resonant cross-section of scattering may be several orders of magnitude higher than the cross-section of Compton effect in the absence of the external field.     

The second Born approximation in electron-helium scattering in a Nd-YAG laser field

The dynamics of laser-assisted elastic collisions in helium is studied using the second-order Born approximation. Detailed calculations of the scattering amplitudes are performed by using the Sturmian basis expansion. Differential cross sections for elastic scattering with the net absorption/emission of up to two photons are calculated for collision energies of 5 eV, 10 eV, and 20 eV. We discuss the influence of the low-energy electrons on the differential cross section (DCS) as a function of the scattering angle for selected choices of the laser frequency and the number of photons exchanged between the external field and electron-helium system.     

Electron-atomic-hydrogen “elastic" scattering in the presence of a laser field

Laser-assisted electron-atomic-hydrogen “elastic" scattering is studied in the first Born approximation. The initial and final states of projectile electron are described by the Volkov wavefunctions; the dressed state of target described by a time-dependent perturbative wavefunction in soft photon approximation. The laser modified cross-sections are calculated in two distinct geometries for laser polarization either parallel or perpendicular to the incident direction of electron. The numerical results shows that the multiphoton cross-sections oscillate by a few orders over the whole scattering angular region. The results for a parallel geometry oscillate more frequently in the intermediate angles; while the results for a perpendicular geometry oscillate more frequently in the forward and backward angles. At large scattering angles, the sum rule of Kroll and Watson is noticeably violated. The laser modification on summed total cross-section increases with field strength, but decreases with field frequency and polarization deviation from the incident direction. Received 18 October 2001 and Received in final form 26 December 2001     

Limited volume thin film deposition on geometrically complicated substrates

In this paper we report a study on the elastic scattering of electrons by lithium and sodium atoms in the presence of circularly polarized resonant laser field within the framework of the two-state rotating wave approximation. The effect of laser on projectile electrons is described by Volkov states. The frequency of the laser field is chosen to match with the 2s–3p (3s–3p) transition frequency in lithium (sodium) atoms. The total and differential elastic cross sections with single photon exchange are calculated for intermediate energies (50–150 eV) and laser intensity (10⁷–10¹¹ W cm^-2). An erratum to this article can be found online at http://dx.doi.org/. An erratum to this article can be found at     

雨介质中球形目标的GHz复合散射特性

将背景空间及其中存在的离散粒子作为一种连续的电介质,得出了背景空间中离散粒子存在时混合体的等效介电常量模型.利用该模型和国际电讯联盟给出的雨衰减测量数据,确定了GHz波段雨介质的等效介电常量并验证了其有效性.得出了雨环境中目标复合散射场的解析式,对雨环境中球形目标的复合微分散射进行了仿真与分析,进而研究了降雨率、电磁波频率及极化状态等因素对复合微分散射的影响.计算表明:降雨对微分散射的影响在10^-3分贝上,电磁波垂直极化时降雨的影响大于其水平极化时的影响.研究结果对精确制导和目标识别等有一定的参考意义.     

第二玻恩近似理论研究激光辅助e-Ar散射

在电子入射方向平行于激光场的极化方向这种特殊的散射模式下，应用第二玻恩近似(SBA)理论，分别利用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对激光场中电子-氩原子散射进行了研究，并与低频近似和实验数据进行了比较.结果表明，第二玻恩近似理论给出的结果与实验符合较好.另外，极化势在激光辅助电子-原子散射中起着重要作用. 关键词： 极化势 第二玻恩近似 微分截面 激光场     

New phenomena in laser-assisted scattering of an electron by a muon

The scattering of an electron by a muon in the presence of a linearly polarized laser field is investigated in the first Born approximation. The theoretical results reveal the following: i) At medium and large scattering angles, many multiphoton processes occur during scattering, and these nonlinear phenomena may predict the resonant state of the electron and the muon formed in the collision process. ii) The photoabsorption (inverse bremsstrahlung) dominates the photoemission (bremsstrahlung), causing the cross section to increase. iii) When the laser polarization deviates from the incident direction, the lasermodified total cross section depends considerably on the azimuthal angle of the scattered electron. The dependence of the cross section on the field strength, polarization direction, and electron-impact energy are studied.     

The effect of intense laser field on the Electronic Raman Scattering of shallow donor impurities in quantum dots

The laser-field dependence of energy levels and donor-related Electronic Raman Scattering is investigated by a quasi-analytical approach. The differential cross section involved in this process is calculated as a function of secondary radiation photon energy. We find that the laser field amplitude and confinement strength have an important influence on the Raman scattering. And the transitions between lower electronic energy states are more sensitive to the laser field.     

Polarisation effect of laser field in inelastic electron - hydrogen collisions

We study the influence of the laser polarization on the electron impact excitation of atomic hydrogen. Our method takes into account the “dressing” of the target states by including the laser-atom interaction to first order time-dependent perturbation theory, while the interaction of the laser field with the incident electron is treated to all orders by using the non relativist Volkov function. The interaction of the fast projectile with the target atom is treated in the first Born approximation. The calculations are performed via two distinct computations. The first one is based on a direct calculation, the second based on a Sturmian approach. Important differences appear between the angular distributions depending on the polarization chosen. Received : 17 february 1998 / Revised : 20 july 1998 / Accepted : 2 september 1998     

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。     

Electron-Helium Atom Collisions in the Presence of a Bichromatic Laser Field

The differential cross section （DCS） for electron-helium atom collisions in the presence of a bichromatic CO2 laser field is investigated as a function of the scattering angle θ by employing first-Born approximation （FBA） with a simple screening electric potential. We discuss in detail the influence of the scattering geometry, the photon energy and the number of photons exchanged on the DCSs. These illustrate that the three factors have important effects on the elastic scattering and the screening electric potential is effective.     

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。     

Resonant scattering of an electron by a muon in the field of light wave

In the frame of the Born approximation we theoretically investigate resonant scattering of an electron by a muon in the field of elliptically polarized electromagnetic wave in the general relativistic case. It is studied kinematics of a scattering of an electron in resonant region. It is derived the expressions for the amplitude and the cross-section of the resonant scattering of an electron by a muon when the invariant intensity parameter of the laser field is small (η_e ≪1). It is demonstrated that the resonant cross-section of a scattering may be several orders of magnitude higher than the cross-section of a scattering in the absence of the external field.     

On the theory of the relativistic cross-sections for stimulated bremsstrahlung on an arbitrary electrostatic potential in the strong electromagnetic field

On the base of relativistic generalized eikonal approximation wave function the multiphoton cross-sections of a Dirac particle bremsstrahlung on an arbitrary electrostatic potential and strong laser radiation field are presented. In the limit of the Born approximation the ultimate analytical formulas for arbitrary polarization of electromagnetic wave have been obtained and numerically analyzed. Received 5 April 2001 / Received in final form 18 March 2002 Published online 28 June 2002     

Resonances and dichroism in the scattering of an electron in an intense laser field by the Coulomb potential

We use a new type of Hamiltonian representing the electron-proton interaction in an intense laser field for an ab initio calculation of the differential scattering cross section. We give the diagrams of the results of calculations of the shapes and widths of the resonances in the cross section of electron scattering by the “field-dressed” Coulomb potential. The resonances emerge because of re-emission of photons by the electron. We also give the angular distribution of the scattered electrons as a function of circular dichroism for different values of the laser field strength and frequency. Zh. éksp. Teor. Fiz. 116, 1241–1249 (October 1999)     

Intense laser field effects on the electron Raman scattering in a strained InGaN/GaN quantum well

The differential cross-section for an intersubband electron Raman scattering process in a strained InGaN/GaN quantum well in the presence of an intense laser field is studied. In the effective-mass approximation, the electronic structure is calculated by taking into account the effects of spontaneous and piezoelectric polarization fields on the confinement potential. Effects of laser field strength, indium composition and the well width on the differential cross-section of the strained quantum well are investigated. Results show that the position and the magnitude of the peaks of emission spectra considerably depend on the laser field strength as well as structural parameters.