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P. Wopperer, B. Faber, P. M. Dinh, P.-G. Reinhard, E. Suraud

Angular distributions of photo-electrons from free Na clusters

Phys. Rev. A (2010) in press

par Mai Seve-Dinh - 8 décembre 2010

We explore, from a theoretical perspective, photo-electron angular distributions (PAD) of the Na clusters Na$_8$, Na$_10$, Na$_12$, Na$_18$, Na$_3^+$, Na$_11^+$, Na$_13^+$, and Na$_19^+$. Basis of the description is the time-dependent local-density approximation (TDLDA), augmented by a self-interaction correction (SIC) to describe ionization properties correctly. The scheme is solved on a numerical grid in coordinate space with absorbing bounds. We assume for each cluster system an isotropic ensemble of free clusters and develop for the case of one-photon emission analytical formulae for computing the orientation averaged PAD on the basis of a few TDLDA-SIC calculations for properly chosen reference orientations. It turns out that all information in the averaged PAD is contained in one anisotropy parameter. We find that this parameter varies very little with system size, but as a whole is crucially influenced by the detailed ionic structure. We also compare with direct orientation averaging and consider one example reaching outside the perturbative regime.