The density of atomic oxygen in an oxygen rf discharge in the Gaseous Electronics Conference reference cell is determined from the intensity ratios of the argon λ=750 nm line (2p1–1s2) and the atomic oxygen lines λ=777 nm (5P–5S) and λ=844 nm (3P–3S). Laser induced fluorescence spectroscopy with two-photon excitation is applied to the oxygen plasma, and the results of both methods are compared. The improved actinometry is based on the calculation of electronic collisional excitation of the upper levels of these transitions. The required information on the electron energy distribution function is obtained from a model calculation of the discharge. Good agreement of the results are obtained, if excitations via dissociative channels and also quenching rates are accounted for.

Axial distributions of negative oxygen ions in an asymmetric, capacitively coupled oxygen radiofrequency discharge (of the gaseous electronics conference reference cell type) are investigated. The O − ion densities are measured by detecting the electrons released after photo-detachment with a Langmuir probe.At small power and a pressure of approximately 10 Pa the axial distributions of both the O − ions and the electrons are flat. At higher power (characterized by voltage amplitudes in excess of 200 V) both quantities exhibit maxima in the central region between the electrodes. These maxima are displaced with increasing pressure (>50 Pa) towards the driven electrode. The absolute concentration of O − is insensitive to admixtures of argon up to 50%. This can be understood, if one assumes that the dominant loss channel for the negative ions involves metastable O 2 (a 1 g ) molecules. This assumption is confirmed by measurements taken with the discharge operating in a pulsed mode.

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Self-biased magnetoelectric (ME) composites, defined as materials that enable large ME coupling under external AC magnetic field in the absence of DC magnetic field, are an interesting, challenging and practical field of research. In comparison to the conventional ME composites, eliminating the need of DC magnetic bias provides great potential towards device miniaturization and development of components for electronics and medical applications. In this review, the current state-of-the-art of the different selfbiased structures, their working mechanisms, as well as their main characteristics are summarized. Further, the nature and requirement of the self-biased magnetoelectric response is discussed with respect to the specific applications. Lastly, the remaining challenges as well as future perspective of this research field are discussed.