Kramers–Henneberger Form of Strong Field Theory with the Correction of Dipole Approximation

We show that the breakdown of dipole approximation can be adopted to explain the asymmetry structure in the photoelectron momentum distributions along the beam propagation direction, which is defined as the photoelectron longitudinal momentum distributions(PLMD), in tunneling regime(K ? 1), based on the strong field approximation theory. The nondipole Hamiltonian for photoelectrons interacting with laser fields from a hydrogen-like atom is transformed into the Kramers–Henneberger frame in our model. To introduce the correction of dipole approximation, the spatial variable is kept in a vector potential (r, t), demonstrating that the breakdown of dipole approximation is the major reason for the shift of the peak in PLMD. The nondipole effects are apparent when circularly polarized lasers are adopted to ionize the atoms, and clear tendency to increase offsets is found for increasing laser intensities.     

Ionization in an intense field considering Coulomb correction

We derive a simple ionization rate formula for the ground state of a hydrogen atom in the velocity gauge under the conditions:ω1 a.u.(a.u.is short for atomic unit) and γ1(ω is the laser frequency and y is the Keldysh parameter).Comparisons are made among the different versions of the Keldysh-Faisal-Reiss(KFR) theory.The numerical study shows that with considering the quasi-classical(WKB) Coulomb correction in the final state of the ionized electron,the photoionization rate is enhanced compared with without considering the Coulomb correction,and the Reiss theory with the WKB Coulomb correction gives the correct result in the tunneling regime.Our concise formula of the ionization rate may provide an insight into the ionization mechanism for the ground state of a hydrogen atom.     

Case(b）情况下NO的非弹性散射及 相关量子干涉的理解

我们已经对原子与双原子分子间的碰撞量子干涉进行了理论研究,为了对 分裂引起的碰撞诱导转动传能进行更一步的研究,建立了洪德情况b下原子双原子分子系统的理论模型.对洪德情况b下原子双原子分子系统干涉程度进行了讨论,并对洪德情况b下NO与He, Ne , Ar碰撞干涉角进行了定量计算。在含时一级波恩近似下,考虑各向异性相互作用势,定量分析转动量子数,实验温度等对干涉角的影响。     

Case(b）情况下NO的非弹性散射及 相关量子干涉的理解

我们已经对原子与双原子分子间的碰撞量子干涉进行了理论研究,为了对 分裂引起的碰撞诱导转动传能进行更一步的研究,建立了洪德情况b下原子双原子分子系统的理论模型.对洪德情况b下原子双原子分子系统干涉程度进行了讨论,并对洪德情况b下NO与He, Ne , Ar碰撞干涉角进行了定量计算。在含时一级波恩近似下,考虑各向异性相互作用势,定量分析转动量子数,实验温度等对干涉角的影响。     

Photoelectron longitudinal momentum distributions containing nondipole effects

This paper proposes a modified strong field approximation model for evaluating nondipole effects on the ionization of an atom in an intense laser field. The photoelectron longitudinal momentum distributions(PLMD) of a hydrogen-like atom exposed to a mid-infrared laser field is calculated. The theoretical results indicate an obvious asymmetry in the PLMD, and an offset of the PLMD peak appears in the opposite direction of the beam propagation due to nondipole effects. The peak offsets of the PLMD increased with the laser intensity, imposed by the initial state of the hydrogen-like atom.