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The effect of silicon oxide surface segregation on the locally-resolved kinetics of the CO oxidation reaction on individual grains of a polycrystalline Pd foil was studied in situ by PEEM, MS and XPS. The silicon oxide formation induced by Si-impurity segregation at oxidizing conditions, was monitored by XPS and its impact on the global and local (spatially resolved) kinetics of the CO oxidation was determined by MS and PEEM. The results reveal a drastic inhibiting effect of silicon oxide on the Pd reactivity towards CO oxidation, manifested both in the collapse of the global CO2 formation rate and in the modified local reactive properties of individual Pd micrograins. The presence of adsorbed oxygen on the Pd surface effectively enhances the silicon segregation to the Pd surface.Graphical Abstract

Two kinds of CVD diamond films were investigated with respect to their thermoluminescent (TL) properties, especially concerning their sensitivity to ionising radiation and to daylight. The films were characterised by means of Raman/photoluminescence/FTIR spectroscopy, XRD, RBS and elastic recoil detection analysis (ERDA). Thermoluminescent (TL) responses of these materials to photons provided by radionuclide 55 Fe source (≈6 keV) over the dose range from 1 to 100 mGy were measured. Typical TL glow curve is a result of two components, one with maximum in range 160-180 °C and the second, between 307-327 °C. In irradiated samples, the first peak is caused by the exposure to daylight, which increases overall TL signal, the second is caused by irradiation by γ-photons. Exploitation of TL properties of CVD diamonds for a photon dosimetry is possible after careful daylight shielding. The sensitivity of used CVD diamond dosimeters was 10 times less than that of TLD 100 (LiF: Mg, Ti) Harshaw dosimeter.

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