Experimental and theoretical study of the Auger cascade following 3d→5p photoexcitation in Kr

Abstract

Resonant Auger transitions from the 3d −1 5p photoexcited states in Kr to the 4s −1 4p −1 5p and 4s −2 5p levels and subsequent Auger decay to the 4p 4 and 4s4p 5 states of Kr 2+ are studied by means of angle-resolved electron spectroscopy. The angular anisotropy parameters β are determined for most of the prominent lines in the spectrum of emitted electrons. It is found that the first-step spectator transitions are strongly anisotropic, while the secondstep participator transitions are almost isotropic. Extensive multiconfiguration Dirac-Fock calculations are performed which include correlations in all of the states involved. Noticeable improvements are achieved in comparison with early calculations. The energy position of the main spectral lines and their intensities are described satisfactorily. It turns out that the interference effects due to coherent excitation of resonances influence the anisotropy of the Auger emission significantly. The calculated β parameters agree very well with the experiment.

Investigation of the cascades in atoms using the global characteristics of spectra

“…Because the X-ray transitions accompanying the cascade decay of inner-shell vacancies are less probable than the Auger transitions, the cascade affected emission spectra are less investigated, the results are mainly obtained for inert gases [27,33,[80][81][82][83][84] as well as for Fe [37], Ag [80], and Pb, Th, U [85]. During the last years some angle resolved studies of the Auger cascades following photoexcitation from an inner shell were performed for Ar, Kr, and Xe [31,[86][87][88][89].…”

Theoretical Auger and photoionization studies for open-shell atoms and ions

“…A series of experimental and theoretical investigations have been carried out on the angular distribution spectra of resonantly excited noble gases [16][17][18][19]21]. From the comparison with observed spectra, our computations clearly demonstrated that the angular dependence of the electron emission can be understood only-if the level structure and splitting is treated properly.…”

“…For a 3d ! 5p excitation in krypton, moreover, both the excitation and de-excitation process take place coherently through a number of levels and must be described in terms of a densitymatrix approach, in order to derive the angular distribution of the emitted electrons [19]. ItÕs likely that this effect is also important in the case of the 3d…”

Level sequence and splitting identification of closely spaced energy levels by angle-resolved analysis of fluorescence light

“…However, less attention has been paid to the influence of overlapping resonances upon the atomic fluorescence, in contrast to the autoionization of inner-shell excited atoms [17][18][19]. Only rather recently, we explored the angular and polarization properties of the emitted photons in the two-step radiative cascade 1s2p…”