Probabilities for adiabatic or near-adiabatic state transformation within a highly excited shell of Li(n = 25) were studied experimentally and theoretically for a time dependent electric field, E⃗(t), and a constant magnetic field, B⃗. The fields were sufficiently weak and the time dependence slow enough such that only states belonging to the chosen shell were involved. The studies show that the dynamics are governed by the approximate hydrogenic character of the system in most cases, but for some specific time dependences it is influenced strongly by core interactions as expressed through the quantum defects, δl. The s-state is effectively decoupled from the rest of the n = 25 manifold due to a very large quantum defect. However the quantum defects of the p, d and f states are shown to play a decisive role in the dynamics. The core interactions lead to avoided crossings, non-adiabatic state transformations, and possibly even phase-interference effects. When a resonance condition pertaining to the hydrogenic character of the system is fulfilled, a linear Stark state is transformed completely into a circular Stark state oriented along E⃗f.

We describe the experimental setup at Centro Atómico Bariloche for the measurement of doubly differential electron distributions, in energy and angle of emission, induced by atomic collisions. We present detailed information about the performance of the equipment including a discussion of instrumental effects that could have affected the measured spectra.

Magnetic, compositional and morphological properties of Zn-Fe-oxide core-shell bimagnetic nanoparticles (MNPs) were studied for three samples with 0.00, 0.06 and 0.10 Zn/Fe ratios, as obtained from Particle-Induced X-ray Emission analysis. The bimagnetic nanoparticles were produced in one step synthesis by the thermal decomposition of the respective acetylacetonates. The nanoparticles present an average particle size between 25-30 nm as inferred from Transmission Electron Microscopy (TEM). High-Resolution TEM images clearly show core-shell morphology for the particles in all samples. The core is composed by an antiferromagnetic (AFM) phase with Wüstite (Fe 1-y O) structure, while the shell is composed by Zn x Fe 3-x O 4 ferrimagnetic (FiM) spinel phase. Despite the low solubility of the Zn in the Wüstite, Electron energy-loss spectroscopy (EELS) analysis indicates that the Zn is distributed almost homogeneously in the whole nanoparticle. This result gives information on the formation mechanisms of the particle, indicating that the Wüstite is formed firstly, and the superficial oxidation results in the FiM ferrite phase with similar Zn concentration than the core. Magnetization and in-field Mössbauer spectroscopy of the Zn-richest nanoparticles indicate that the AFM phase is strongly coupled to the FiM structure of the ferrite shell, resulting in a bias field (H EB) appearing below T N FeO , with H EB values that depends on the core-shell relative proportion. Magnetic characterization also indicates a strong magnetic frustration for the samples with higher Zn concentration, even at low temperatures.