Wavelength dependence of nonsequential double ionization in He

Strong Field Double Ionization: The Phase Space Perspective

“…1, a typical double ionization probability as a function of the intensity of the laser field is plotted. Similar knees have been observed in experimental data [1,4,20,21,22,23,24,25,26] and successfully reproduced by quantal computations on atoms and molecules [5,27,28,29]. In a recent series of articles [8,9,12,13,29,30,31] characteristic features of double ionization were reproduced using classical trajectories and this success was ascribed to the paramount role of correlation [12].…”

Nonsequential Double Ionization of Helium

“…One case where one can see a clear effect of the dynamics of one electron on the other is in the experiments reported by Fittinghoff et al [2] and more recently by several other groups [3,4]. In these experiments the single and double ionization yields of He in a linearly polarized field are measured to very high accuracy.…”

Classical collisional trajectories as the source of strong-field double ionization of helium in the knee regime

“…However, none of the two nonsequential ionization (NSI) mechanisms can completely explain the experimental observations. For the "shake-off" model, it can not give the reason for the decrease in the double ionization yields as the polarization of the laser field departs from linear [7][8][9]. In the "recollision" model, the returning electrons are known to have a maximum classical kinetic energy of ∼ 3.2U p (U p = e 2 F 2 /4m e ω 2 ), so one can determine a minimum intensity required for the rescattering electron to have enough energy to excite the inner electron.…”