Two-photon above-threshold ionization of helium

Anisotropy parameters in two-color two-photon above-threshold ionization

Direct two-photon double ionization of helium

The role of electron correlation, i.e. the electron-electron repulsion, in non-sequential two-photon double ionization of helium has been widely debated in literature, and the issue is not yet fully resolved. We present total cross sections for this process obtained within a one dimensional model of the helium atom. In our calculations the cross sections are obtained in two ways. Firstly, the t...

Phase measurement of resonant two-photon ionization in helium.

We study resonant two-color two-photon ionization of helium via the 1s3p (1)P(1) state. The first color is the 15th harmonic of a tunable Ti:sapphire laser, while the second color is the fundamental laser radiation. Our method uses phase-locked high-order harmonics to determine the phase of the two-photon process by interferometry. The measurement of the two-photon ionization phase variation as...

Different escape modes in two-photon double ionization of helium

The quadrupole channel of two-photon double ionization of He exhibits two distinctly different modes of correlated motion of the photoelectron pair. The kinematics of the mode associated with the center-of-mass motion favors large total momenta maximized at parallel emission where the interelectron repulsion is strong. In contrast, the mode associated with the relative motion favors large relat...

Equal energy sharing double photo ionization of the Helium atom at 20eV and 40eV above threshold

In this article we present triple differential cross sections for equal energy sharing kinematics for double photoionization of the helium atom at 20 and 40eV above threshold in the framework of the hyperspherical partial wave theory. This supplements our earlier work [1] in which we were successful in showing fully, gauge independence of the results in our formalism. Also in this work we treat...