Electronic decay of the photoexcited Ca resonance

Abstract

A study of the photoionization of atomic calcium in the region of the 3p 5 3d4s 2 1 P 1 resonance at 31.41 eV is described. Measurements are made of the photoelectron angular distributions and branching ratios, corresponding to the case where the Ca + ion is left in excited Rydberg levels converging to the ground level of the doubly charged ion. The data are used to examine the validity of LS coupling and the spectator model of resonant Auger decay.

Coherence and correlations in photoinduced Auger and fluorescence cascades in atoms

“…The recent development of the e-e coincidence experiments have confirmed these expectations. The angular correlations between two emitted electrons from an Auger cascade have been measured by various groups Ueda et al, 1999aUeda et al, , 2001Ueda et al, , 2003bWehlitz et al, 1999;Turri et al, 2001;Viefhaus et al, 2005;Da Pieve et al, 2005). Note that we shall not discuss here the experiments in which a direct photoelectron emission is measured in coincidence with an Auger electron.…”

“…Non-coincidence angular distribution measurements are nowadays a rather routine experimental method in the analysis of resonant Auger electrons Huttula et al, 2001aHuttula et al, , 2003De Fanis et al, 2001Heinäsmäki, 2001;Kitajima et al, 2001Kitajima et al, , 2002Kitajima et al, , 2006Oura et al, 2004;Sankari et al, 2001;Shimizu et al, 2000;Snell et al, 2000;Ueda et al, 1999aUeda et al, , 2001Ueda et al, , 2003aYoshida et al, , 2005, for earlier references see the reviews by Armen et al (2000) and by Piancastelli (2000)). …”

“…Even more detailed spectroscopic information on the initial-and final-state quantum numbers can be obtained by measuring the angular correlations between the successively emitted electrons in the Auger cascade or Auger electron-fluorescence cascade (Kabachnik, 1997;Kabachnik et al, 1999;Kabachnik and Ueda, 1995). In contrast to the rather common non-coincidence measurements, the coincidence angle resolved experiments, which involve two Auger electrons from a cascade, are still rather scarce Wehlitz et al, 1999;Turri et al, 2001;Ueda et al, 1999aUeda et al, , 2001Ueda et al, , 2003bDa Pieve et al, 2005). Furthermore, only a few experiments were reported in which an emitted Auger electron was detected in coincidence with polarized fluorescence photons (Beyer et al, 1995Ueda et al, 1998).…”

“…In contrast to the rather common non-coincidence measurements, the coincidence angle resolved experiments, which involve two Auger electrons from a cascade, are still rather scarce Wehlitz et al, 1999;Turri et al, 2001;Ueda et al, 1999aUeda et al, , 2001Ueda et al, , 2003bDa Pieve et al, 2005). Furthermore, only a few experiments were reported in which an emitted Auger electron was detected in coincidence with polarized fluorescence photons (Beyer et al, 1995Ueda et al, 1998).…”

“…Being determined from the experiment, these amplitudes permit one to predict all other characteristics of the process even though some of them are impossible to measure by means of present-day experimental facilities. First attempts to realize the complete experiment for the resonant Auger process have been discussed and published recently (Ueda et al, 1999a;O'Keeffe et al, 2003O'Keeffe et al, , 2004.…”