Controlling double ionization of atoms in intense bichromatic laser pulses

We consider the classical dynamics of a two-electron system subjected to an intense bichromatic linearly polarized laser pulse. By varying the parameters of the field, such as the phase lag and the relative amplitude between the two colors of the field, we observe several trends from the statistical analysis of a large ensemble of trajectories initially in the ground state energy of the helium atom: High sensitivity of the sequential double ionization component, low sensitivity of the intensities where nonsequential double ionization occurs while the corresponding yields can vary drastically. All these trends hold irrespective of which parameter is varied: the phase lag or the relative amplitude. We rationalize these observations by an analysis of the phase space structures which drive the dynamics of this system and determine the extent of double ionization. These trends turn out to be mainly regulated by the dynamics of the inner electron

Comment on "Classical Simulations Including Electron Correlations for Sequential Double Ionization"

Comment on "Classical Simulations Including Electron Correlations for Sequential Double Ionization" [arXiv:1204.3956

Recollision scenario without tunneling : Role of the ionic core potential

The standard model of strong laser physics, the recollision scenario, omits the ionic core potential after tunneling. Strikingly, although the Coulomb interaction drives all stages of recollision, the maximum energy the electrons bring back to the core is found by ignoring it. We resolve this long-standing paradox by showing that this good agreement stems from a fortuitous cancellation at high intensities. Instead of the three step model, we find that the Coulomb interaction can be fully integrated into a purely classical scenario that explains recollisions without invoking tunneling

Annular billiard dynamics in a circularly polarized strong laser field

We analyze the dynamics of a valence electron of the buckminsterfullerene molecule (C60) subjected to a circularly polarized laser field by modeling it with the motion of a classical particle in an annular billiard. We show that the phase space of the billiard model gives rise to three distinct trajectories: "Whispering gallery orbits", which only hit the outer billiard wall, "daisy orbits" which hit both billiard walls (while rotating solely clockwise or counterclockwise for all time), and orbits which only visit the downfield part of the billiard, as measured relative to the laser term. These trajectories, in general, maintain their distinct features, even as intensity is increased from 10^10 to 10^14 W*cm^-2. We attribute this robust separation of phase space to the existence of twistless tori

Quantum-classical correspondence in circularly polarized high harmonic generation

Using numerical simulations, we show that atomic high order harmonic generation, HHG, with a circularly polarized laser field offers an ideal framework for quantum-classical correspondence in strong field physics. With an appropriate initialization of the system, corresponding to a superposition of ground and excited state(s), simulated HHG spectra display a narrow strip of strong harmonic radiation preceded by a gap of missing harmonics in the lower part of the spectrum. In specific regions of the spectra, HHG tends to lock to circularly polarized harmonic emission. All these properties are shown to be closely related to a set of key classical periodic orbits that organize the recollision dynamics in an intense, circularly polarized field

Self Organization Map to Assess Forest Development and Problems with Multiple Regression Analysis

Sustainability is a burning factor in the forestry sector around the world. Understanding sustainability is also a critical question. This research examined the status of Bangladesh forestry by indicating the needs of forest products and the efficiency of forest policy and management practices, and relates sustainability with scarcity situations Bangladesh is a country of beauty with forest and river. The natural significant of Bangladesh is mainly depends on its forest. The greenness of our country is the gift of heaven. But we are not aware of this marvelous asset. In this work we have evaluated the status of forest of Bangladesh under the approach of soft computing. The method is Self Organization Map (SOM). We classified the data set by Multiple Regression Analysis (MRA). The study area we have designed the south part of the Bangladesh