In the interaction of two electric quadrupoles, there is at short range a contact term proportional to the second derivative of a delta function. This contact term contributes to the hyperfine splitting of bound states of two particles with spin one or higher-for example the bound state of Ω − and a nucleus with spin one. The contact hyperfine splitting occurs in states with orbital angular mom...

The previous analysis of the short-range NN repulsion originating from the Goldstone boson exchange hyperfine interaction between constituent quarks is revisited. We study in which respects the repulsion depends on the radial form of the spin-spin quark-quark force. We show that while the radial form affects the structure of the 6Q wave function, the short-range repulsion in the NN system persi...

A study of the hydrogen hyperfine couplings of the Mn-cluster of the oxygen-evolving complex of Photosystem II in the S(2) state of the Kok cycle by means of hyperfine sublevel correlation spectroscopy was achieved. Features corresponding to hyperfine interaction of at least two hydrogen nuclei were detected. Combining our results with previous ENDOR data, hyperfine constants were determined, a...

Organic semiconductors offer a unique environment to probe the hyperfine coupling of electronic spins to a nuclear spin bath. We explore the interaction of spins in electron-hole pairs in the presence of inhomogeneous hyperfine fields by monitoring the modulation of the current through an organic light emitting diode under coherent spin-resonant excitation. At weak driving fields, only one of t...

We present a detailed theoretical analysis of the noble-gas nuclear spin relaxation due to the anisotropic magnetic-dipole hyperfine interaction between the noble-gas nucleus and alkali-metal valence electron vis à vis the already well-understood (spin-conserving) isotropic magnetic-dipole hyperfine interaction in alkali-metal–noble-gas systems. We find that, for all pairs in which the noblegas...

The muonic helium atom (μe2He) represents the simple three-body atomic system. The interaction between magnetic moments of the muon and electron leads to the hyperfine structure (HFS) of the energy levels. The investigation of the energy spectrum of this atom is important for the check of quantum electrodynamics for three-particle bound state. The ground state hyperfine splitting was measured m...

We present the results of a detailed study of the thermally assisted-resonant-tunneling relaxation rate of Mn12 acetate as a function of an external, longitudinal magnetic field and find that the data can be fit extremely well to a Lorentzian function. No hint of inhomogeneous broadening is found, even though some is expected from the Mn nuclear hyperfine interaction. This inconsistency implies...

A first testing ground for QED in the combined presence of a strong Coulomb field and a strong magnetic field is provided by the precise measurement of the hyperfine structure splitting of hydrogenlike 209Bi. We present a complete calculation of the one-loop self-energy correction to the first-order hyperfine interaction for various nuclear charges. In the low-Z regime we almost perfectly agree...

A high-precision examination of the hyperfine spectrum of 6LiI in comparison with 7LiI shows a shift in the iodine nuclear electric quadrupole moment that cannot be accounted for by a model in which the electric field gradient at the iodine site is assumed to depend only upon the internuclear distance between Li and I. The other hyperfine interactions are consistent between the two isotopomers,...

Relativistic formulas for the electric quadrupole moment of a hydrogenlike atom, induced by the hyperfine interaction, are derived for ns and np1/2 states. Both the magnetic dipole and electric quadrupole hyperfine interactions are taken into account. The formulas are valid for ions with arbitrary nuclear charge and spin. The induced quadrupole moment is compared with the nuclear quadrupole mom...