Charge Distributions of Krypton Ions Following Photo-Ionization in theMShell

Abstract

Charge distributions of krypton ions that result from ionization in the M shell by x rays have been measured with a magnetic mass spectrometer. X-ray energies ranged from 100 to 1400 eV. The following results are derived from the charge spectra: (a) In filling a hole in the 3d shell, an Auger process which generates two continuum electrons competes strongly with the common Auger process which generates one continuum electron. This so-called double Auger process occurs in (31=b4)% of the events, (b) The Coster-Kronig transitions 3p-3dN and 3p-3d3d have nearly equal intensities, (c) Partial photoabsorption coefficients for M electrons are poorly predicted by the Stobbe-Hall formula even for energies above 1 keV. Calculated shake-off probabilities of M and N electrons are given for the sudden removal of a 3s, 3p, or 3d electron.

Resonance-enhanced multiple ionization of krypton at an x-ray free-electron laser

“…Below the L edge, at 1.5 keV, the highest yield is found for Kr 3+ corresponding to single-photon M-shell ionization as observed at synchrotrons [26,27]. The predicted ion yield for Kr 4+ is too low, probably due to the disregard of double Auger decay which occurs in 31% of the 3d photoionization events [26]. For higher charge states, reached by absorption of additional photons, the theoretical and experimental data fit very well, indicating that the dominant processes are properly taken into account.…”

“…The ion yield for 1.5 keV photon energy is drawn in black (dark gray) and for 2 keV in red (light gray). Below the L edge, at 1.5 keV, the highest yield is found for Kr 3+ corresponding to single-photon M-shell ionization as observed at synchrotrons [26,27]. The predicted ion yield for Kr 4+ is too low, probably due to the disregard of double Auger decay which occurs in 31% of the 3d photoionization events [26].…”

Effectiveness of projectile screening in single and multiple ionization of Ne by B2+

“…Indeed, inner or deeper valence shell ionization followed by postcollisional electron emission, like Auger, Coster-Kronig, or shake-off processes, can generate a vacancy cascade and highly charged target ions are produced after the collisional process. Only recently, after the exclusive measurement of multiple ionization of Ne by fast protons [13], the dynamic signatures of these time-delayed mechanisms were clearly identified and a good description of multiple ionization was obtained by combining the independent electron approximation with branching ratios for multiple ionization obtained from photoionization measurements [14][15][16][17][18][19]. This approach has been successfully used in the last years to describe multiple ionization in the intermediate-to high-velocity regime for several multielectron atoms [9,10,12,13,20,21,29,30].…”

Coincidence Measurements of Krypton-Krypton Collisions

“…Indeed, a study of the energy levels of krypton indicates that many such Auger electrons with energies between 40 and 255 eV are possible. Krause and Carlson, 14 who studied M-shell vacancies in krypton, indicate that in 31% of the cases two, rather than one, Auger electrons are emitted. These would contribute to a continuum rather than to welldefined electron peaks.…”