Key Laboratory for Quantum Optics and Center for Cold Atom Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.
Phys Rev Lett. 2013 Jan 4;110(1):013001. doi: 10.1103/PhysRevLett.110.013001. Epub 2013 Jan 2.
A calculation of the second-order (rescattering) term in the S-matrix expansion of above-threshold ionization is presented for the case when the binding potential is the unscreened Coulomb potential. Technical problems related to the divergence of the Coulomb scattering amplitude are avoided in the theory by considering the depletion of the atomic ground state due to the applied laser field, which is well defined and does not require the introduction of a screening constant. We focus on the low-energy structure, which was observed in recent experiments with a midinfrared wavelength laser field. Both the spectra and, in particular, the observed scaling versus the Keldysh parameter and the ponderomotive energy are reproduced. The theory provides evidence that the origin of the structure lies in the long-range Coulomb interaction.
本文给出了阈上电离 S 矩阵展开的二阶（再散射）项的计算，其中束缚势为非屏蔽库仑势。通过考虑由于应用激光场而导致的原子基态的耗尽，该理论避免了与库仑散射幅度发散相关的技术问题，而原子基态的耗尽是有明确定义的，并不需要引入屏蔽常数。我们专注于低能结构，该结构在最近使用中红外波长激光场的实验中被观察到。该理论再现了光谱，特别是与 Keldysh 参数和动理学能量的观察到的标度关系，这表明结构的起源在于长程库仑相互作用。
