Coherences in the decay of autoionizing states in photoionization. I. Exchange effect between photo- and Auger electrons

Abstract

An interference effect on angular correlation patterns due to exchange of Auger and photoelectrons of the same energy is discussed. The detection in coincidence of the Auger and photoelectrons may reveal a striking angular correlation pattern when a synchrotron light source is tuned so that the Auger and photoelectron energies are nearly equal. This efFect is present even when only one electron is detected, but is strongly reduced by the averaging over the direction of the undetected electron. PACS number(s): 32.80.Fb, 32.80.Hd

Electron correlation in two-photon double ionization of helium from attosecond to XFEL pulses

“…This interference bears some resemblance to the well-known exchange interference between e.g. photo-electrons and Auger electrons [54][55][56][57]. There is, however, a fundamental difference: while the exchange interference is intrinsically controlled by atomic parameters, namely the energy and lifetime (width) of the Auger electron, the novel interference observed here is truly a dynamical effect present only for E 1 E 2 Figure 4.…”

Experimental Observation of Post-Collision Interaction and Interference Effects in Resonant Double Photoionization Processes

“…Then, the experimental challenge is to achieve a resolving power, in both the exciting source and the detectors, comparable with the width G of the involved intermediate atomic states. Such a resolution is mandatory in order to observe the interference effects typical of coherence [3][4][5]. The process of double photoionization of rare gases offers unique opportunities to investigate these two topics with the same experiment.…”

“…Then, due to electron exchange, strong interference effects are expected in the angular and energy distributions of the outgoing electrons. In this case, the two-step model does not hold anymore [3,4,6], and must be replaced by a one-step model where the two electrons are not specified as photoelectron or Auger electron. The intermediate state is then considered as a resonance embedded in the double continuum.…”

Postcollision Interaction in the Coincident Emission of Photoelectrons and Auger Electrons at Small Relative Angles

“…For the correct theoretical formulation of the sequential process the conventional two-step formulation must be replaced by a one-step formula [1], the antisymmetry of the final-state wave function leads to two amplitudes in the transition matrix element T fi [2], and angle-dependent effects of postcollision interaction (PCI) play an important role [3]. One then gets an analytical expression for the nontrivial dependences on the emission angles (k a , k b ) and the actual kinetic energies (e a , e b ); the latter entering as differences to the nominal kinetic energies e 0 P hn 2 E 1 I and e 0 A E 1 I 2 E 11 I of the "photo"electron and the "Auger" electron (hn is the photon energy, E 1 I and E 11 I the intermediate hole state and final state ionization energy, respectively).…”