Recent Publications

Daniel Dundas

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  1. Title: Multiphoton double ionization of atoms and molecules by FEL XUV light

    Author(s): Taylor K.T., Parker J.S., Dundas D., Meharg K.J., Doherty B.J.S., Murphy D.S., McCann J.F.

    Journal Of Electron Spectroscopy And Related Phenomena, 144, No. Sp. Iss. SI, pp. 1191-1196 (JUN 2005)

    doi: 10.1016/j.elspec.2005.01.270

    We review recent work carried out in Belfast which handles the few-electron dynamics of atomic and molecular systems exposed to high frequency, high intensity laser fields. The design and application of the quantitatively accurate computational methods is discussed. The Belfast work is illustrated by results for double ionization of helium and the hydrogen molecule by FEL XUV light where in each case the two electrons have been handled in full-dimensionality. (c) 2005 Elsevier B.V. All rights reserved.

  2. Title: Molecular effects in the ionization of N2, O2, and F2 by intense laser fields

    Author(s): Dundas D., Rost J.-M.

    Physical Review A, 71, No. 1, Art. No. 013421 (JAN 2005)

    doi: 10.1103/PhysRevA.71.013421

    In this paper we study the response in time of N2, O2, and F2 to laser pulses having a wavelength of 390 nm. We find single-ionization suppression in O2 and its absence in F2, in accordance with experimental results at λ=800 nm. Within our framework of time-dependent density functional theory we are able to explain deviations from the predictions of intense-field many-body S-matrix theory (IMST). We confirm the connection of ionization suppression with destructive interference of outgoing electron waves from the ionized electron orbital. However, the prediction of ionization suppression, justified within the IMST approach through the symmetry of the highest occupied molecular orbital (HOMO), is not reliable since it turns out that—e.g., in the case of F2—the electronic response to the laser pulse is rather complicated and does not lead to dominant depletion of the HOMO. Therefore, the symmetry of the HOMO is not sufficient to predict ionization suppression. However, at least for F2, the symmetry of the dominantly ionized orbital is consistent with the nonsuppression of ionization.