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Spatially resolved x-ray fluorescence (XRF) based analysis employing incident beam sizes in the low micrometer range (μ XRF) is widely used to study lateral composition changes of various types of microstructured samples. However, up to now the quantitative analysis of such experimental datasets could only be realized employing adequate calibration or reference specimen. In this work, we extent the applicability of the so-called reference-free XRF approach to enable reference-free μ XRF analysis. Here, no calibration specimen are needed in order to derive a quantitative and position sensitive composition of the sample of interest. The necessary instrumental steps to realize reference-free μ XRF are explained and a validation of ref.-free μ XRF against ref.-free standard XRF is performed employing laterally homogeneous samples. Finally, an application example from semiconductor research is shown, where the lateral sample features require the usage of ref.-free μ XRF for quantitative analysis. [ABSTRACT FROM AUTHOR]

The degradation of organic pollutants by transition metal activated peroxymonosulfate (PMS) has important application value in the field of advanced oxidation. MnO2/SiC composite catalyst was prepared by hydrothermal method on the surface of silicon carbide (SiC), which was used to activate PMS to degrade and remove methylene blue (MB) from water. The results show that MnO2 is uniformly attached to the surface of SiC in the form of particles, and the removal rate of MB by MnO2/SiC-PMS system reaches 99% within 40 min. The MnO2/SiC-PMS system can achieve high degradation efficiency of MB over a wide pH range (5.0~9.0), while 5 mmol/L Cl- and NO3- had no significant effect on the MnO2/SiC-PMS system. Phosphate and bicarbonate have quenching effect on oxidative free radicals, leading to a decrease in the degradation efficiency of MB in the MnO2/SiC PMS system. The results of free radical quenching experiments indicate that plays a major role in the MnO2/SiC-PMS system. In addition, MnO2/SiC has good recyclability. [ABSTRACT FROM AUTHOR]

The design of semiconductor-based heterojunction structures can be turned useful to raise the efficiency of nuclear micro-batteries. In this study, we have investigated a micro-power alphavoltaic battery by using a lab-made software. The nuclear battery consists of an In0.49Ga0.51P/GaAs heterostructure irradiated by americium-241 (Am241) alpha particles with an average kinetic energy of 5.485 MeV. The alphavoltaic battery exhibits an overall active area of 1 cm². Based on a comprehensive analytical model, the device current density-voltage J(V) and output electric power P(V) characteristics are simulated extracting the energy conversion efficiency. The model takes into account the reflection of the incident alpha particles, the ohmic losses, the effect of the boundary between the two layers, and the depletion region borders. Different values of the radioisotope apparent activity density, the emitter and base dopant concentrations, and the surface recombination velocities in both the front and back layers are considered during the simulations to optimize the battery performance. The present study reports that by irradiating by a 2.4 mCi/cm² Am241 source, the obtained energy conversion efficiency of the battery can reach 10.31% with a maximum output power density of 16.07 μW/cm². Therefore, In0.49Ga0.51P/GaAs heterostructure coupled with Am241 seems a promising design for long- term energy supply in harsh environments. [ABSTRACT FROM AUTHOR]