Production and Decay of Atomic K-Shell Vacancy States

Details Production and Decay of Atomic K-Shell Vacancy States Production and Decay of Atomic K-Shell Vacancy States

May 2008

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008aas...212.0309g&link_type=abstract

American Astronomical Society, AAS Meeting #212, #3.09; Bulletin of the American Astronomical Society, Vol. 40, p.185

Physics

Atomic Physics

Scientific paper

K-shell photoabsorption calculations are important for a variety of astrophysical processes, in particular, determining the elemental abundances of the interstellar medium from observed X-ray absorption spectra. Previously, we performed reliable K-shell photoabsorption calculations for oxygen and neon ions that were used to determine elemental abundances from observed X-ray binary emissions. Here, we have executed detailed R-matrix calculations for carbon ions, where we have included both Auger broadening and relaxation effects by using an optical potential and pseudoorbitals with the necessary pseudoresonance elimination respectively. Also of astrophysical importance, especially for determining the charge-state distribution following K-shell excitation and/or ionization, is the competition between fluorescence (ejection of a photon, no charge change) and Auger decay (ejection of an electron, ionic charge change of +1). Our recent investigations on the accuracy of the existing 1s-vacancy fluorescence and Auger data base have revealed numerous deficiencies in that compilation. Those data were determined from configuration average, non-relativistic, singly-charged atomic physics calculations and were then scaled up through Z=30 for all isoelectronic sequences through the iron peak elements. We demonstrate the significance of including properly such physical effects as correct configuration averaging, semi-relativistic (i.e., spin-orbit) effects, and configuration interaction. Most recently, we have performed calculations that revealed anomalous behavior of the radiative and Auger rates, and the associated fluorescence yields, of the six electron K-shell vacancy isoelectronic sequence, exhibited as non-monotonic behavior as a function of Z. This behavior is explained in terms of an accidental degeneracy, an avoided-crossing of two nearly-degenerate spin-orbit coupled states. Consequently, we have demonstrated that, in general, even interpolation of rates and yields along an isoelectronic sequence is unsafe and for one more reason, explicit calculations for each member of a sequence is necessary.
This work was funded in part by NASA (APRA), NASA (SHP) SR&T, and UK PPARC grants.

Affiliated with

Also associated with

No associations

Rating

Production and Decay of Atomic K-Shell Vacancy States does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Production and Decay of Atomic K-Shell Vacancy States, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Production and Decay of Atomic K-Shell Vacancy States will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1393777