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- ItemAtomic and molecular suite of R-matrix codes for ultrafast dynamics in strong laser fields and electron/positron scattering(Bristol : IOP Publ., 2020) Wragg, J.; Benda, J.; MaÅ¡Ãn, Z.; Armstrong, G.S.J.; Clarke, D.D.A.; Brown, A.C.; Ballance, C.; Harvey, A.G.; Houfek, K.; Sunderland, A.; Plummer, M.; Gorfinkiel, J.D.; Van Der Hart, H.We describe and illustrate a number of recent developments of the atomic and molecular ab initio R-matrix suites for both time-dependent calculations of ultrafast laser-induced dynamics and time-independentcalculations of photoionization and electron scattering. © 2019 Published under licence by IOP Publishing Ltd.
- ItemExcited state distribution and spin-effects in strong-field excitation of neutral Helium(Bristol : IOP Publ., 2015) Zimmermann, Henri; Eilzer, Sebastian; Eichmann, UlliWe investigated the principal quantum number n distribution of excited states resulting from the interaction of Helium with strong, short laser pulses. We find excellent agreement with predictions of the semiclassical frustrated tunneling ionization (FTI) model [1] as well as fully quantum mechanical calculations. Furthermore, the excitation process directly populates triplet excited states due to the breakdown of the Russel-Saunders coupling scheme for high orbital angular momentum l states of Helium, which are predominantly populated in the strong laser field.
- ItemNondipole effects in terahetz-pulse-assisted strong-field ionization(Washington, DC : Soc., 2022) Milošević, Dejan B.; Habibović, DinoNondipole effects in processes assisted by a THz field having the strength of a few MV/cm can be significant due to its long wavelength. We illustrate this for strong-laser-field-induced ionization assisted by a THz field. To this end, we generalize our strong-field-approximation theory so that it includes the first-order term in a 1/c expansion of the vector potential. We show that in this case, in addition to a shift of the maximum of the photoelectron momentum distribution, the differential ionization probability as well as the cutoff energy can be significantly increased. For an explanation of these unexpected results we use the saddle-point method adjusted to include nondipole effects.