Dresden 2011 – scientific programme

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A: Fachverband Atomphysik

A 5: Photoionization I

A 5.4: Talk

Monday, March 14, 2011, 15:15–15:30, BAR 106

Origin of Low Energy Structures in Photoelectron Spectra Induced by Mid-Infrared Strong Laser Fields — •Liu Chengpu and Hatsagortsyan Karen Z. — Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany

Based on a semiclassical model incorporating tunneling and Coulomb field effects, the origin of the low-energy structures (LES) in above-threshold ionization spectrum observed in recent experiments [1] is identified. Following a systematic investigation how the LES depend on laser polarization, pulse duration and the atomic potential range, we classified and quantified the Coulomb effects. We proved that the non-perturbative contribution of the multiple forward scattering into Coulomb focusing is responsible for the appearance of LES [2]. The shape of the LES is due to the interplay between multiple forward scattering of an ionized electron and the electron momentum disturbance by the Coulomb field immediately after the ionization determine. The former determines the appearance of the LES, while the latter does the positions of the LES peaks. The dependence of the LES height and width on the laser intensity or wavelength is also investigated and a simple scaling law is derived.

[1] C. I. Blaga et al., Nature Phys. 5, 335 (2009); W. Quan et al., Phys. Rev. Lett. 103, 093001 (2009).

[2] C. Liu and K. Z. Hatsagortsyan, Phys. Rev. Lett. 105, 113003 (2010).