6 research outputs found
Isotope shift calculations for atoms with one valence electron
This work presents a method for the ab initio calculation of isotope shift in
atoms and ions with one valence electron above closed shells. As a zero
approximation we use relativistic Hartree-Fock and then calculate correlation
corrections. The main motivation for developing the method comes from the need
to analyse whether different isotope abundances in early universe can
contribute to the observed anomalies in quasar absorption spectra. The current
best explanation for these anomalies is the assumption that the fine structure
constant, alpha, was smaller at early epoch. We test the isotope shift method
by comparing the calculated and experimental isotope shift for the alkali and
alkali-like atoms Na, MgII, K, CaII and BaII. The agreement is found to be
good. We then calculate the isotope shift for some astronomically relevant
transitions in SiII and SiIV, MgII, ZnII and GeII.Comment: 11 page
Atomic calculations and search for variation of the fine structure constant in quasar absorption spectra
A brief review of the search for variation of the fine structure constant in
quasar absorption spectra is presented. Special consideration is given to the
role of atomic calculations in the analysis of the observed data. A range of
methods which allow to perform calculations for atoms or ions with different
electron structure and which cover practically all periodic table of elements
is discussed. Critical compilation of the results of the calculations as well
as a review of the most recent results of the analysis are presented.Comment: 9 pages, 2 figures. Based on the talk at the Symposium on Atomic
Physics: A Tribute to Walter Johnson, Notre Dame, 5 April 2008. Reference 26
is correcte