The one-photon two-electron emission process is suggested as a spectroscopic tool for studying the features of Cooper pairs in superconducting materials with a pairing mechanism. It is shown that the correlated angle distributions of the photo-excited electron pair carry detailed information on the Cooper pair wave function in the momentum space. Utilising circularly polarised photons offers the possibility of investigating aspects pertinent to the phase of the superconducting gap function.

more »

... e information are accessed via measuring the circular dichroism in the two-electron angular and energy distribution, i.e. the difference in the recorded two-electron photoemission spectra for left and right circularly polarised photon.