title: Scaling of the low-energy structure in above-threshold ionization in the tunneling regime: theory and experiment.
abstract: 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.
authors: 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.
authors: L
authors: L
authors: Guo
authors: S S
authors: SS
authors: Han
authors: X
authors: X
authors: Liu
authors: Y
authors: Y
authors: Cheng
authors: Z Z
authors: ZZ
authors: Xu
authors: J
authors: J
authors: Fan
authors: J
authors: J
authors: Chen
authors: S G
authors: SG
authors: Chen
authors: W
authors: W
authors: Becker
authors: C I
authors: CI
authors: Blaga
authors: A D
authors: AD
authors: DiChiara
authors: E
authors: E
authors: Sistrunk
authors: P
authors: P
authors: Agostini
authors: L F
authors: LF
authors: DiMauro