Staggering Effects in Nuclear and Molecular Spectra

Abstract

It is shown that the recently observed ΔJ=2 staggering effect (i.e. the relative displacement of the levels with angular momenta J, J+4, J+8,…, relatively to the levels with angular momenta J+2, J+6, J+10, …) seen in superdeformed nuclear bands is also occurring in certain electronically excited rotational bands of diatomic molecules (YD, CrD, CrH, CoH), in which it is attributed to interband interactions (bandcrossings). In addition, the ΔJ=1 staggering effect (i.e. the relative displacement of the levels with even angular momentum J with respect to the levels of the same band with odd J) is studied in molecular bands free from ΔJ=2 staggering (i.e. free from interband interactions/bandcrossings). Bands of YD offer evidence for the absence of any ΔJ=1 staggering effect due to the disparity of nuclear masses, while bands of sextet electronic states of CrD demonstrate that ΔJ=1 staggering is a sensitive probe of deviations from rotational behaviour, due in this particular case to the spin-rotation and spin-spin interactions.