Helium, direct double photoionization

Figure 4.43 Energy- and angle-resolved triple-differential cross section for direct double photoionization in helium at 99 eV photon energy. The diagram shows the polar plot of relative intensity values for one electron (ea) kept at a fixed position while the angle of the coincident electron (eb) is varied. The data refer to electron emission in a plane perpendicular to the photon beam direction for partially linearly polarized light (Stokes parameter = 0.554) and for equal energy sharing of the excess energy, i.e., a = b = 10 eV. Experimental data are given by points with error bars, theoretical data by the solid curve.

Figure 4.44 Illustration of energy- and angle-resolved two-electron emission following direct double photoionization in helium at 80 eV photon energy using linearly polarized light (electric field vector along the x-axis). Both electrons are detected in a plane perpendicular to the photon beam direction, the direction of one electron (ea) is fixed at a = 180°, = 150° and a = 90° (first, second and third columns in the figure), while...

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