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A pair of transverse wobbling bands is observed in the nucleus ^{135}Pr. The wobbling is characterized by ΔI=1, E2 transitions between the bands, and a decrease in the wobbling energy confirms its transverse nature. Additionally, a transition from transverse wobbling to a three-quasiparticle band comprised of strong magnetic dipole transitions is observed. These observations conform well to results from calculations with the tilted axis cranking model and the quasiparticle rotor model.

High-spin states in 72Br were studied with the EUROBALL III spectrometer using the 40Ca(40Ca,alpha3p1n) reaction. The negative-parity band observed in this experiment displays a signature inversion around spin I = 16. The interpretation within the cranked Nilsson-Strutinsky approach shows that this signature pattern is a signal of a substantial triaxial shape change with increasing spin where the nucleus evolves from a triaxial shape with rotation about the intermediate axis at low spin through a collective prolate shape to a triaxial shape but with rotation about the shortest principal axis at high spin.

Rotational bands with strong magnetic dipole transitions have been observed in the doubly odd nuclei ${}^{82}\mathrm{Rb}$ and ${}^{84}\mathrm{Rb}$. These bands show the characteristic features of magnetic rotation. They are the first evidence of this new kind of nuclear excitation in the $A\ensuremath{\approx}80$ region. The results are well reproduced within the framework of the tilted axis cranking model on the basis of four-quasiparticle configurations of the type $\ensuremath{\pi}(\mathrm{fp})\ensuremath{-}\ensuremath{\pi}({g}_{9/2}^{2})\ensuremath{-}\ensuremath{\nu}({g}_{9/2})$.

The electromagnetic dipole strength below the neutron-separation energy has been studied for the xenon isotopes with mass numbers A = 124, 128, 132 and 134 in nuclear resonance fluorescence experiments using the ELBE bremsstrahlung facility at Helmholtz-Zentrum Dresden-Rossendorf and the HIgS facility at Triangle Universities Nuclear Laboratory Durham. The systematic study gained new information about the influence of the neutron excess as well as of nuclear deformation on the strength in the region of the pygmy dipole resonance. The results are compared with those obtained for the chain of molybdenum isotopes and with predictions of a random-phase approximation in a deformed basis. It turned out that the effect of nuclear deformation plays a minor role compared with the one caused by neutron excess. A global parametrization of the strength in terms of neutron and proton numbers allowed us to derive a formula capable of predicting the summed E1 strengths in the pygmy region for a wide mass range of nuclides.

The M1 excitations in the nuclide 90Zr have been studied in a photon-scattering experiment with monoenergetic and linearly polarized beams from 7 to 11 MeV. More than 40 J(π)=1+ states have been identified from observed ground-state transitions, revealing the fine structure of the giant M1 resonance with a centroid energy of 9 MeV and a sum strength of 4.17(56) μ(N)(2). The result for the total M1 strength and its fragmentation are discussed in the framework of the three-phonon quasiparticle-phonon model.

The M1 excitations in the nuclide 90Zr have been studied in a photon-scattering experiment with monoenergetic and linearly polarized beams from 7 to 11 MeV. More than 40 J(π)=1+ states have been identified from observed ground-state transitions, revealing the fine structure of the giant M1 resonance with a centroid energy of 9 MeV and a sum strength of 4.17(56) μ(N)(2). The result for the total M1 strength and its fragmentation are discussed in the framework of the three-phonon quasiparticle-phonon model.

A photon scattering experiment has been performed on the odd-[ital A] nucleus [sup 143]Nd. Strong dipole excitations have been detected in the energy region around 3.2 MeV. This is near the expected position of the two-phonon (2[sup +][direct product]3[sup [minus]]) multiplet in the even-even neighboring nucleus [sup 142]Nd. The summed dipole strength between 2.8 and 3.6 MeV in [sup 143]Nd is in agreement with the sum rule for weak particle coupling to the core nucleus [sup 142]Nd. Model calculations in a harmonic approximation are in a very good agreement with the experiment and they suggest a two-phonon (2[sup +][direct product]3[sup [minus]]) particle structure of the excitations in [sup 143]Nd.

Three rotational bands in 74Kr were studied up to (in one case one transition short of) the maximum spin I(max) of their respective single-particle configurations. Their lifetimes have been determined using the Doppler-shift attenuation method. The deduced transition quadrupole moments reveal a modest decrease, but far from a complete loss of collectivity at the maximum spin I(max). This feature, together with the results of mean field calculations, indicates that the observed bands do not terminate at I = I(max).

The nuclides {sup 98}Mo and {sup 100}Mo have been studied in photon-scattering experiments by using bremsstrahlung produced from electron beams with kinetic energies from 3.2 to 3.8 MeV. Six electromagnetic dipole transitions in {sup 98}Mo and 19 in {sup 100}Mo were observed for the first time in the energy range from 2 to 4 MeV. A specific feature in the two nuclides is the deexcitation of one state with spin J=1 to the 0{sup +} ground state as well as to the first excited 0{sup +} state, which cannot be explained in standard models. We present a model that allows us to deduce the mixing coefficients for the two 0{sup +} shape-isomeric states from the experimental ratio of the transition strengths from the J=1 state to the 0{sup +} ground state and to the 0{sup +} excited state.

The nuclides 98Mo and 100Mo have been studied in photon-scattering experiments by using bremsstrahlung produced from electron beams with kinetic energies from 3.2 to 3.8 MeV. Six electromagnetic dipole transitions in 98Mo and 19 in 100Mo were observed for the first time in the energy range from 2 to 4 MeV. A specific feature in the two nuclides is the de-excitation of one state with spin J = 1 to the 0+ ground state as well as to the first excited 0+ state, which cannot be explained in standard models. We present a model that allows us to deduce the mixing coefficients for the two 0+ shape-isomeric states from the experimental ratio of the transition strengths from the J = 1 state to the 0+ ground state and to the 0+ excited state.

Following theoretical predictions of competing prolate and oblate potential-energy minima, we present experimental evidence for the coexistence of prolate and oblate nuclear shapes which are associated in a given nucleus with the same single-quasiproton orbital. Prolate \ensuremath{\Delta}I=2 and oblate \ensuremath{\Delta}I=1 bands observed in the $^{119}\mathrm{I}$ nucleus are proposed as built on an ${\mathrm{h}}_{11/2}$ proton with low K and high K, respectively.

In an axially symmetric, strongly rotating quadrupole deformed nucleus, the projection /ital K/ of the angular momentum along the symmetry axis is a partially conserved quantity. A /ital K/ isomer (/ital K/=25) at low excitation energy has been observed in /sup 182/Os which decays into the ground-state band (/ital K/=0). The associated electromagnetic lifetime at spin /ital I/approx.25 can be interpreted in terms of tunneling of a system displaying strong pairing fluctuations across a barrier which separates configurations in which the nucleus rotates about the symmetry axis and about an axis perpendicular to it. A hindrance factor approx.10/sup /minus/6/--10/sup /minus/9/ for the process is calculated, in overall agreement with the data.

Evidence is presented for a ..pi..h/sub 9/2/ band crossing at surprisingly low rotational frequency in the odd-neutron /sup 185/Pt and odd-proton /sup 183/Ir nuclei. The proton nature of the crossing is indicated by measured B(M1;I..-->..I-1)/B(E2;I..-->..I-2) ratios, strongly supported by theoretical values from both the semiclassical Doenau and Frauendorf approach and a variable-core particle-rotor calculation employing cranked-shell-model matrix elements. However, the actual crossing frequency is greatly overestimated by the cranking method using generally accepted model parameters.