Precision physics of simple atoms: QED tests, nuclear structure and fundamental constants

Quantum electrodynamics is the first successful and still the most successful quantum field theory. Simple atoms, being essentially QED systems, allow highly accurate theoretical predictions. Because of their simple spectra, such atoms have been also efficiently studied experimentally frequently offering the most precisely measured quantities. Our review is devoted to comparison of theory and experiment in the field of precision physics of light simple atoms. In particular, we consider the Lamb shift in the hydrogen atom, the hyperfine structure in hydrogen, deuterium, helium-3 ion, muonium and positronium, as well as a number of other transitions in positronium. Additionally to a spectrum of unperturbed atoms, we consider annihilation decay of positronium and the g factor of bound particles in various two-body atoms. Special attention is paid to the uncertainty of the QED calculations due to the uncalculated higher-order corrections and effects of the nuclear structure. We also discuss applications of simple atoms to determination of several fundamental constants

In-situ incorporation of Ce-zeolite during soft sparking plasma electrolytic oxidation

This study demonstrates that the optimisation of electrical processing parameters during plasma electrolytic oxidation allows the single-step incorporation of nanoparticles with complex 3D structures into the outer porous structure of the growing PEO coating. In particular, this work evaluates the zeolite particle uptake mechanism during the soft sparking regime. Four aluminate-based electrolytes with different concentrations of zeolite nanoparticles (0–10 g l−1) were studied. The encapsulation of Ce within the zeolite nanoparticles (Ce-zeolite) was evaluated by FTIR, SEM/EDS, XRD and TGA. The successful incorporation of zeolite in PEO coatings was confirmed by SEM-EDS and FIB/TEM. Zeolite and Ce-loaded nanoparticles were incorporated non-reactively by adsorption and entrapment into molten oxide during coating growth at the surface of PEO coatings. Reactive incorporation was also identified in the inner layers as a result of the field assisted migration of the nanoparticles through flaws and defects, leading to their thermal decomposition. The corrosion behaviour of PEO coatings improved noticeably upon the addition of zeolite nanoparticles, whereas the inclusion of cerium within zeolite led to an incremental improvement in performance.</p