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We have performed Raman studies of a LiNiPO4 single crystal at temperatures below and above the phase transition to a magnetically ordered state at 5 and 25 K, respectively. A shift of some phonon lines during the transition to a magnetically ordered state was observed that is explained by a significant spin-phonon interaction. We identified the anomalous Raman lines using the shell-model calculation. It was found that with an increase in temperature, some external vibrational modes shift to the low-frequency region, and the internal vibrational modes of the (PO4)3– tetrahedra shift to the high-frequency region. This anomalous behavior of the vibrational modes is explained by the presence of magnetostriction that can selectively act on the bonds between ions in the crystal upon the transition to a magnetically ordered state. [ABSTRACT FROM AUTHOR]

LiNiPO4, multifunctional material with potential ionic current and magnetoelectric applications, was studied by IR optical spectroscopy and lattice dynamic shell-model calculations. We present IR phonon parameters of lithium-nickel-phosphate, both experimental (at T = 30 K) and calculated ones. Multiferroic properties of lithium-nickel-phosphate were confirmed by temperature evolution of phonon band parameters due to spin-phonon interaction revealed for a number of phonon modes. The most pronounced effect was registered for B2u IR-vibrational mode near 202 cm−1, which demonstrates anomalous temperature behavior in the vicinity of magnetic ordering (TN = 21.8 K) indicating the coupling to the magnetic subsystem. This mode is assigned to the complex normal vibration including the librations of the PO4 tetrahedra, out-of-plane vibrations of the Li atoms, and the in-plane vibrations of the magnetic Ni atoms along the b axis. The detected phonon shift at TN can be explained by the striction phenomena. [ABSTRACT FROM AUTHOR]

The first-excited state g factor of 26 Mg has been measured relative to the g factor of the Mg 24 ( 2 1 + ) state using the high-velocity transient-field technique, giving g = + 0.86 ± 0.10 . This new measurement is in strong disagreement with the currently adopted value, but in agreement with the sd -shell model using the USDB interaction. The newly measured g factor, along with E ( 2 1 + ) and B ( E 2 ) systematics, signal the closure of the ν d 5 / 2 subshell at N = 14 . The possibility that precise g -factor measurements may indicate the onset of neutron pf admixtures in first-excited state even–even magnesium isotopes below 32 Mg is discussed and the importance of precise excited-state g -factor measurements on sd shell nuclei with N ≠ Z to test shell-model wavefunctions is noted. [ABSTRACT FROM AUTHOR]

Abstract: By taking nuclear core excitations into account, detailed structure calculations of 89  Λ Y have been performed as a function of the Λ spin–orbit splitting. The obtained wave functions have been used to estimate the reaction cross sections within the distorted-wave impulse approximation (DWIA). A theoretical explanation is given quantitatively for the first time of how to understand the doublet substructure of each major peak observed in medium-heavy hypernuclear production. A small Λ spin–orbit splitting of around is deduced, a value consistent with the small ΛN two-body spin–orbit interactions deduced from γ-ray measurements in three light hypernuclei. [Copyright &y& Elsevier]

A detailed investigation of the contribution from Coulomb effects to the observed mirror energy difference diagrams in nuclei in the lower part of the upper fp shell is presented by means of large-scale shell-model calculations. [ABSTRACT FROM AUTHOR]

The β decay of 96Ag (Z=47,N=49) was investigated by measuring positrons, X rays as well as β-delayed protons and γ rays. The γ radiation was studied by means of germanium detectors and a NaI total-absorption spectrometer. Two β-decaying isomers in 96Ag were established with half-lives of 4.40(6) and 6.9(6) s and tentative spin–parity assignments of (8+) and (2+), respectively. For both isomers, the intensities of β transitions to low-lying levels of 96Pd (Z=46,N=50) and β-delayed proton decays to levels in 95Rh (Z=45,N=50) were measured. Several new 96Pd levels were firmly established. The level energies, their γ decays and the Gamow–Teller decay of 96Ag are compared to shell-model predictions. A new low-lying level in 95Rh was found at 680 keV excitation energy. Through a comparison with low-lying states of N=50 isotones, this level is interpreted as the first excited 7/2+ state built on the proton 9/2+ ground state. The assignments of further excited states in 95Rh are discussed. [Copyright &y& Elsevier]

The yrast and a few of the yrare negative-parity states in the 49V nucleus have been investigated employing the 27Al(28Si, α 2p)49V reaction. Most of the levels and the deexciting γ rays, reported earlier in 49V, have been observed in this measurement using the Indian National Gamma Array (INGA) spectrometer. Mean lifetimes up to the band-terminating state have been extracted following Doppler Shift Attenuation Method (DSAM), and reduced transition probabilities have been deduced. Large Scale Shell Model (LSSM) calculations in the full fp shell employing various effective interactions with no restrictions imposed on the valence orbitals have been performed. The results that have been obtained from calculations are in fair agreement with the experimentally obtained values. [ABSTRACT FROM AUTHOR]