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Lecture Stefaan Cottenier


14 January 2011 FWN-Building 5113.0201, Nijenborgh 4, 9747 AG, Groningen
Speaker: Dr. Stefaan Cottenier
Affiliation: Center for Molecular Modeling (CMM), Ghent University, Belgium
Title: Electron penetration into the nucleus and its effect on the quadrupole interaction
Date: Fri Jan 14, 2011
Start: 11.00
Location: FWN-Building 5113.0201
Host: M. Filatov
Telephone: +31 50 363 4377


A series expansion of the interaction between a nucleus and its surrounding electron distribution provides terms that are well-known in the study of hyperfine interactions: the familiar quadrupole interaction and the less familiar hexadecapole interaction. If the penetration of electrons into the nucleus is taken into account, various corrections to these multipole interactions appear. The best known correction is a scalar term related to the isotope shift and the isomer shift. This seminar, however, discusses a related tensor correction, which modifies the quadrupole interaction if electrons penetrate the nucleus: the quadrupole shift. We describe the mathematical formalism and provide first-principles calculations of the quadrupole shift for a large set of solids. Fully relativistic calculations that explicitly take a finite nucleus into account turn out to be mandatory. Our analysis shows that the quadrupole shift becomes appreciably large for heavy elements. Implications for experimental high-precision studies of quadrupole interactions and quadrupole moment ratios are discussed. Most of the content of this seminar is reported in Ref. [1], updated with very recent experimental follow-up work [2].

[1] K. Koch, K. Koepernik, D. Van Neck, H. Rosner, S. Cottenier, Physical Review A 81 (2010) 032507.

 [2] D. Dewald, J. Grabow, in preparation.


Last modified:22 October 2012 2.31 p.m.