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Staggering Effects in Nuclear and Molecular Spectra

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Published: Dec 5, 2019
DOI: https://doi.org/10.12681/hnps.2193
Dennis Bonatsos
Institute of Nuclear Physics, NCSR "Demokritos"
C. Daskaloyannis
Department of Physics, Aristotle University of Thessaloniki
S. B. Drenska
Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences
N. Karoussos
Institute of Nuclear Physics, NCSR "Demokritos"
J. Maruani
Laboratoire de Chimie Physique, CNRS and UPMC
N. Minkov
Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences
P. P. Raychev
Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences
R. P. Roussev
Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences
Abstract

It is shown that the recently observed AI = 2 staggering seen in superdeformed nuclear bands is also occurring in certain electronically excited rotational bands of diatomic molecules, in which it is attributed to interband interactions (bandcrossings). In addition, a AI = 1 staggering effect (i.e. a relative displacement of the levels with even angular momentum I with respect to the levels of the same band with odd /) is seen in molecular bands free from AI = 2 staggering (i.e. free from interband interactions/bandcrossings). The magnitude of the AI = 1 staggering is found to be constant as a function of 7, in agreement with the predictions of algebraic models (u(ll) model, u(16) model, Vector Boson Model) used for the description of octupole nuclear bands, i.e. bands corresponding to pear-like shapes, suggesting that the presence of AI = 1 staggering in rotational bands of diatomic molecules could be attributed in general to the inequality of the masses of the two atoms of which the molecule is composed. The existence of the AI = 1 staggering effect is corroborated by the fact that separate Dunham expansions for the even levels and the odd levels of such bands give similar but different parameter sets.

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