Inelastic electron scattering by an intense laser beam of the Hermite-Gaussian (0, 1) mode

We point out that the inelastic electron scattering, which originates form the non-linear Compton scattering in intense laser field, is much more prominent in the Hermite-Gaussian (0, 1) mode than that in the (0, 0) mode. This result could be of potential interest for physicists to observe the non-linearity of the free-electron-photon interaction in experiment.     

Scaling laws of electron acceleration driven by an intense laser pulse

We studied the scaling laws for slow-electron acceleration driven by an intense laser pulse in a vacuum, the ponderomotive acceleration scenario (PAS) scheme. With 3D test particle simulation by numerically solving the relativistic Lorentz–Newton equation of motion, the maximum electron energy gain was found to be proportional to the laser intensity (a₀), the laser beam width (w₀), and inversely proportional to the laser pulse duration (τ). Theoretical analyses and a physical explanation based on the ponderomotive potential model (PPM) are presented. PACS 42.50.Vk; 41.75.Jv; 42.60.Jf     

Inelastic electron scattering from a Coulomb potential in a laser field

We present a theoretical study of inelastic electron scattering from a fixed Coulomb potential in the presence of a laser field, based on analytic expressions for the two-photon continuum-continuum transition matrix element. We present here the particular case of incident and scattered light polarizations orthogonal to each other and to the incident electron momentum. Results are given for the cross sections corresponding to the detection of electrons and polarized photons in coincidence, and for the detection of polarized photons only.     

Scaling of wave-packet dynamics in an intense midinfrared field

A theoretical investigation is presented that examines the wavelength scaling from near-visible (0.8 micro m) to midinfrared (2 micro m) of the photoelectron distribution and high harmonics generated by a "single" atom in an intense electromagnetic field. The calculations use a numerical solution of the time-dependent Schr?dinger equation (TDSE) in argon and the strong-field approximation in helium. The scaling of electron energies (lambda2), harmonic cutoff (lambda2), and attochirp (lambda -1) agree with classical mechanics, but it is found that, surprisingly, the harmonic yield follows a lambda -(5-6) scaling at constant intensity. In addition, the TDSE results reveal an unexpected contribution from higher-order returns of the rescattering electron wave packet.     

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)     

Elastic electron scattering in an intense field and two-photon emission

The elastic scattering amplitude, taking into account the mass correction to the propagation function, is found for electrons interacting with an intense electromagnetic field characteristic of non-linear quantum electrodynamics. The probability for two-photon emission e → e2γ, the mass correction to the probability for one-photon emission and the mass correction to the anomalous field-dependent magnetic moment of the electron are found with the aid of the amplitude.     

Radiation corrections to the electron inelastic scattering by an intense stationary laser beam

By solving the Dirac-Lorentz equation numerically with a perturbative predictor-corrector method, we find that the electron inelastic scattering by an intense stationary laser beam is heavily modified by the radiation reaction when the electron is injected upon the laser beam with a large crossing angle (θ>10°). This is the first time the Dirac-Lorentz equation is applied to study the interaction of an electron with a real laser beam in the Hermite-Gaussian mode.     

Formation of ground-state vibrational wave packets in intense ultrashort laser pulses

The formation of coherent vibrational wave packets in the electronic ground state of neutral molecules in intense ultrashort laser pulses and their subsequent detection by means of recently developed pump-probe experiments are discussed. The wave packet formation is due to the pronounced dependence of the strong-field ionization rate on the internuclear distance. This leads to a deformation of the initial wave function due to an internuclear-distance dependent depletion. The phenomenon is demonstrated with a time-dependent wave packet study for molecular hydrogen.     

Mott scattering of a Klein-Gordon particle in an intense laser field

We study the Mott scattering of charged spinless particles in the presence of an intense plane wave laser pulse with fixed propagation direction and arbitrary duration and shape. We derive two equivalent forms of the transition amplitude and we discuss the relation between the respective results obtained in the case of a laser pulse and the monochromatic case. We obtain the condition defining the boundaries of the “bright” domain (the domain of allowed values in the energy-direction space of the scattered particle) and we illustrate our results with numerical examples.     

Backscattering of an intense laser beam by an electron

We present a novel, simple asymptotic expansion for the spectrum of radiation that is backscattered from a laser by a counterpropagating (or copropagating) electron. The solutions are presented in such a way that they explicitly show the relative merit of using an intense laser and of an energetic electron beam in x-ray production in the single particle regime. Simple scaling laws are given.     

氦原子在啁啾激光与中红外组合场中产生的单个阿秒脉冲

通过Crank Nicolson方法数值求解一维氦原子的含时Schrdinger方程,研究了啁啾激光与中红外激光形成组合场驱动氦原子发射高次谐波的特点.研究结果表明,在组合场驱动下,高次谐波平台区能得到很大的扩展,其截至位置得到大幅度扩展,对平台区不同阶次范围的高次谐波进行叠加均能得到单个的阿秒脉冲,最短可实现46 as的单个脉冲输出,经分析发现,中红外场的加入,不仅使高次谐波的平台得到扩展,而且提高了平台区前端的谐波强度.通过经典计算和对电离几率特点的讨论,解释了发生这种现象的原因.     

Redshift in the optical absorption of ZnO single crystals in the presence of an intense midinfrared laser field

We report time-resolved electroabsorption of a weak probe in a 500 μm thick zinc-oxide crystal in the presence of a strong midinfrared pump in the tunneling limit. We observe a substantial redshift in the absorption edge that scales with the cube root of intensity up to 1 TW/cm(2) (0.38 eV cm(2/3) TW(-1/3)) after which it increases more slowly to 0.4 eV at a maximum applied intensity of 5 TW/cm(2). The maximum shift corresponds to more than 10% of the band gap. The change in scaling occurs in a regime of nonperturbative high-order harmonic generation where electrons undergo periodic Bragg scattering from the Brillouin zone boundaries. It also coincides with the limit where the electric field becomes comparable to the ratio of the band gap to the lattice spacing.     

Cyclotron dynamics of electron wave packets in topological insulators in an external magnetic field

The evolution of electron wave packets formed from surface states in topological insulators located in an external magnetic field is studied. The electron and spin densities of the wave packets under consideration are calculated analytically and are visualized. The influence of the main characteristics of the wave packets (the spin polarization) on the splitting and the change in their forms with time is considered.     

Electromagnetic wave scattering by an external field

The quantum electrodynamics of bilocal fields is used to calculate the triangular Feynman diagrams describing the elastic scattering of a classical electromagnetic wave by an external Coulomb field. The total contribution of the diagrams is nonzero because of the violation of both the Furry theorem (CP or T symmetries) and the Ward identities. The cross section for this scattering process is found for low and high energies. A comparison with Compton scattering and Euler—Heisenberg scattering is given.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 38–47, August 1995.     

极化门控制下中红外激光场驱动He原子产生的单个阿秒脉冲

由中红外激光场(波长为2128nm)驱动He原子,在极化门的控制下,通过强场近似方法(SFA)研究了He原子发射高次谐波的特点.研究表明,在这种组合场驱动下He原子可产生截止位置很高的高次谐波,并且在接近截止位置的平台区展现了超连续的特点,对该超连续部分的高次谐波进行叠加,可得到宽度为44.5as的单个超短脉冲.为了了解该超短阿秒脉冲的产生机理,我们对高次谐波谱的发射过程进行了时频分析,分析表明由于极化门的存在,有效地抑制了极化门以外的阿秒脉冲的发射,从而获得单个阿秒脉冲.     

Multiphoton stimulated bremsstrahlung for broad (in the momentum representation) electron wave packets in an ultrashort laser pulse field

We consider features of absorption and emission of external laser field quanta by a broad (in the momentum representation) electron wave packet during its scattering from a potential center. Various scattering modes for the electron wave packet in a high-intensity laser field are analyzed using perturbation theory of potential energy. It is found that the absorption of laser field energy by an electron is substantially more effective as compared to the case of a plane wave. The important role of a number of interference effects associated with the large width of the initial electron momentum distribution is demonstrated.     

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.     

极化门控制下中红外激光场驱动He原子产生的单个阿秒脉冲

由中红外激光场（波长为2128nm）驱动He原子,在极化门的控制下,通过强场近似方法(SFA)研究了He原子发射高次谐波的特点.研究表明,在这种组合场驱动下He原子可产生截止位置很高的高次谐波,并且在接近截止位置的平台区展现了超连续的特点,对该超连续部分的高次谐波进行叠加,可得到宽度为44.5as的单个超短脉冲．为了了解该超短阿秒脉冲的产生机理,我们对高次谐波谱的发射过程进行了时频分析,分析表明由于极化门的存在,有效地抑制了极化门以外的阿秒脉冲的发射,从而获得单个阿秒脉冲．