Semiclassical theory of laser-assisted dissociative recombination

Dipolar focusing in laser-assisted positronium formation

“…Consider a positron beam whose initial velocity v 0 is parallel to the laser polarization vector. This relative orientation of v 0 and e is the most efficient for the Coulomb focusing effect [24,25]; therefore, we expect that this geometry will be efficient for the dipolar focusing as well. In spite of this geometry, our simulations are three-dimensional since they take into account the full dimensionality of the hydrogen atom.…”

“…A hydrogen atom in an excited state possesses an effective dipole moment leading to a longrange interaction between e + and H(n) [20]. A combination of the dipolar field and a monochromatic laser field can produce the dipolar focusing effect similar to the Coulomb focusing effect in the processes of double photoionization [21,22], electron bremsstrahlung [23], radiative recombination [24], and dissociative recombination [25]. The dipolar focusing effect can be expected to play a role in similar laser-assisted positron scattering processes, such as the process of photorecombination involving positrons and atoms [26].…”

“…Another interesting feature of the present problem is the absence of chaos: the probability as a function of the impact parameter does not exhibit fractal structures; irregularities in the P(b) dependence simply represent statistical uncertainties in the CTMC calculations. This is in contrast to the problem of the motion of a charged particle in a is chaotic [24,25,29,30].…”