Attosecond Strobing of Two-Surface Population Dynamics in DissociatingH2+ (original) (raw)
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Physical Review A, 2010
Triple-differential cross sections for two-photon double ionization of molecular hydrogen are presented for a central photon energy of 30 eV. The calculations are based on a fully ab initio, nonperturbative, approach to the time-dependent Schrödinger equation in prolate spheroidal coordinates, discretized by a finite-element discrete-variable-representation. The wave function is propagated in time for a few femtoseconds using the short, iterative Lanczos method to study the correlated response of the two photoelectrons to short, intense laser radiation. The current results often lie in between those of Colgan et al [J. Phys. B 41 (2008) 121002] and Morales et al [J. Phys. B 41 (2009) 134013]. However, we argue that these individual predictions should not be compared directly to each other, but preferably to experimental data generated under well-defined conditions. PACS numbers: 33.80.-b, 33.80.Wz, 31.15.A-
Attosecond electro-nuclear dynamics of H2 double ionization
2007
The ultrafast electronic and nuclear dynamics of H2 laser-induced double ionization is studied using a time-dependent wave packet approach that goes beyond the fixed nuclei approximation. The different double ionization pathways are analyzed by following the evolution of the total wave function during and after the pulse. We show that the rescattering of the first ionized electron produces a coherent superposition of excited molecular states which presents a pronounced transient ionic character. This attosecond excitation is followed by field-induced double ionization and by the formation of short-lived autoionizing states which decay via double ionization. These two different double ionization mechanisms may be identified by their signature imprinted in the kinetic-energy distribution of the ejected protons.
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Physical Review Letters, 2007
The ultrafast electronic and nuclear dynamics of H2 laser-induced double ionization is studied using a time-dependent wave packet approach that goes beyond the fixed nuclei approximation. The double ionization pathways are analyzed by following the evolution of the total wave function during and after the pulse. The rescattering of the first ionized electron produces a coherent superposition of excited molecular states which presents a pronounced transient H + H − character. This attosecond excitation is followed by field-induced double ionization and by the formation of short-lived autoionizing states which decay via double ionization. These two double ionization mechanisms may be identified by their signature imprinted in the kinetic-energy distribution of the ejected protons.
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Physical Review A, 2010
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Attosecond control in photoionization of hydrogen molecules
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Two-color coherent control of H+2 photodissociation in intense laser fields
Physical Review Letters, 1993
We study the multiphoton dissociation of H2 + by a coherent superposition of an intense short pulsed laser radiation and one of its harmonies (second or third), in a phase-Iocked regime. We show that the total dissociation probability, the energy distribution, and the direction of ejection of the protons are very sensitive to the relative phase of the two radiations. A high degree of control may th us be achieved for the branching ratio between dissociation via bond-softening and above-threshold dissociation, in the realm of current experimental capabilities. PACS numbers: 33.80.Gj, 33 .80.Wz, 34.50.Rk Molecular dissociation in strong laser fields has been actively investigated in the past few years, both experimentally and theoretically. Several interesting processes have been found : (j) above-threshold dissociation (ATO) with stimulated emission as weil as multiphoton absorption occurring in the dissociation continuum; (ij) bond softening, [2,3] when a potential barrier in the dressed potential curves is sufficiently lowered by the radiative interaction that the initial vibration al level becornes unbound; (jji) suppression of dissociation, or stabilization due to temporary vibrational trapping in upper potential wells in the dressed potential curves [51. The relative importance of these three competing processes depends on the initial vibration al level, the laser intensity and wavelength, and the pulse duration . From the existing studies the A TO process appears to be the "Ioser," at least when starting from a mixture of vibrational levels, because dissociation by bond softening is very rapid as soon as the potential barrier can be overpassed.
Journal of Physics: Conference Series, 2012
We have carried out calculations of the triple-differential cross section for one-photon double ionization of molecular hydrogen for a central photon energy of 75 eV, using a fully ab initio, nonperturbative approach to solve the time-dependent Schrödinger equation in prolate spheroidal coordinates. The spatial coordinates ξ and η are discretized in a finite-element discrete-variable representation. The wave packet of the laser-driven two-electron system is propagated in time through an effective short iterative Lanczos method to simulate the double ionization of the hydrogen molecule. For both symmetric and asymmetric energy sharing, the present results agree to a satisfactory level with most earlier predictions for the absolute magnitude and the shape of the angular distributions. A notable exception, however, concerns the predictions of the recent time-independent calculations based on the exterior complex scaling method in prolate spheroidal coordinates [Phys. Rev. A 82, 023423 (2010)]. Extensive tests of the numerical implementation were performed, including the effect of truncating the Neumann expansion for the dielectronic interaction on the description of the initial bound state and the predicted cross sections. We observe that the dominant escape mode of the two photoelectrons dramatically depends upon the energy sharing. In the parallel geometry, when the ejected electrons are collected along the direction of the laser polarization axis, back-to-back escape is the dominant channel for strongly asymmetric energy sharing, while it is completely forbidden if the two electrons share the excess energy equally.