The X-ray scanning microscope PtyNAMi at beamline P06 of PETRA III at DESY in Hamburg, Germany, is designed for high-spatial-resolution 3D imaging with high sensitivity. Besides optimizing the coherent ux density on the sample and the precision mechanics of the scanner, special care has been taken to reduce background signals on the detector. The optical path behind the sample is evacuated up until the sensor of a four-megapixel detector that is placed into the vacuum. In this way, parasitic scattering from air and windows close to the detector is avoided. The instrument has been commissioned and is in user operation. The main commissioning results of the low-background detector system are presented. A signal-to-noise model for small object details is derived that includes incoherent background scattering.
In this work we investigate the organic products of the synthesis of Co-based nanoparticles in benzyl alcohol. Our GC and in situ IR studies provide the experimental proofs for the formation of benzaldehyde, toluene and isopropanol in the
reaction solution. These organic products can be correlated with formation of cobalt-based nanoparticles with oxidation
state from 0 to 3+. These results shine the light on the complexity of organic and inorganic reactions in solution during crystallization of nanoparticles.
The understanding of the gas sensing mechanism at a fundamental level implies the knowledge of the state of preadsorbed
surface species. Some question marks on the commonly accepted ideas were raised by the recorded higher
sensitivity of sensors to CO in nitrogen and by the fact that the combustion of CO was observed in air and in humid
nitrogen. These facts question the monopoly of oxygen ions as the reaction partners for CO and they were the driving
force for thereby presented investigations. DRIFT Spectroscopy and resistance measurements have been simultaneously
applied to discriminate between the species that are actively taking part in the sensing processes and spectators. The
comparison between the different sensors has been focused on verifying whether the observed phenomena are general or
whether they depend on the technology. It was observed that for SnO<sub>2</sub> sensors, the reaction of oxygen, with water results
in the formation of terminal hydroxyls and the release of an electron to the conduction band. It indicates that water
compete with reducing gases for the oxygen ions. This phenomenon was independent of the technology and thus it
could be SnO<sub>2</sub> characteristic. It was shown that CO reacts preferentially with ionosorbed oxygen at the surface of tin
dioxide. In the case of lack of oxygen different scenarios are possibly dependent on hydration state of the surface.