The Microscopic Recollision Dynamics And Electron Correlation In Strong-field Nonsequential Double Ionization Of Ar Atom

The nonsequential double ionization(NSDI) in the interaction of matter and intense laser pulses is systematically studied by using a three-dimensional classical micro-canonical model in the dissertation. The content mainly contains the dependence of above-threshold ionization on the carrier-envelope phase(CEP) of few-cycle pulses and the microscopic recollision dynamics in the nonsequential double ionization at laser intensities below and above the recollision threshold.The ion momentum distributions of Ar atom in nonsequential double ionization with a few-cycle laser pulse are investigated using the three-dimensional classical micro-canonical model. It is found that the momentum distribution has a strong dependence on the carrier-envelope phase of the few-cycle pulse. The centre of gravity of the asymmetry distribution shifts from negative to positive ion momentum with the carrier-envelope phase increasing and it will be reversed when the carrier-envelope phase changes byπ. The momentum distributions of the Ar2+ ion show an excellent agreement with the experimental results[Phys.Rev.Lett.93,263001 (2004)] when we take into account the change of the Coulomb potential between the nuclear and electronic in the process of recollision.Nonsequential double ionization of Ar atom below the recollision threshold is also investigated with the three-dimensional classical ensembles. The calculated results reveal a dominance of events for electron emission into opposite hemispheres, a clear minimum of the correlated electron-electron momentum distributions at the origin and a single peak structure of the Ar2+ ions longitudinal momentum spectra near zero momentum. The momentum spectra of the Ar2+ ions agree with the experimental results [Phys. Rev. Lett.101 053001 (2008)] quantitatively. Trajectory back analyses show that the microscopic physical mechanism of Ar NSDI have the distinction with different intensity of the laser. When laser intensity equal to 0.7×10!4W/cm2, one recollision dominates the process of the recollision. However, the domination convert to multiple recollisions as the laser intensity decreases to 0.4×1014W/cm2.In addition, the Coulomb attraction between the ion and electron plays an important role in microscopic dynamics of the electron in the process of Ar NSDI and at last influences the final-state correlated electron-electron momentum distributions strongly. Moreover,statistics shows that the ratio of the back to back emission will not increase with the decreaseing of the intensity of the pulse.