Untersuchung von CeOx−,PrOx\mathrm{CeO_x-, PrO_x}- und CexPr1−xO2−δ\mathrm{Ce_xPr_{1-x}O_{2-\delta}}-Filmen auf Si(111) mittels hochenergetischer Röntgen-Photoelektronenspektroskopie

The intention of this work is to shed light on two much discussed topics in the study of rare earth oxides (REO) by hard x-ray photoelectron spectroscopy (HAXPES): (i) Due to the comlex spectral shape of the Ce3d region, there have been many discussions on proper approaches to determine the concentration of Ce$^3+$ and Ce$^4+$ species in CeO$_x$ over the last decades. (ii) Recently, the true electron structure of rare earth oxides gained new attention, since ab intio calculations showed the necessity of considering additional inter atomic charge transfer to Ce5d levels. Using HAXPES and resonant HAXPES, the question of the true electronic structure of rare earth oxides is approached from the experimental side. As a third topic, the obtained results for cerium oxide and praseodymium oxide are applied in order to investigate the plasma oxidized mixed oxide Ce$_x$Pr$_1−x$O$_2−δ$ grown on Si(111) during thermal reduction

Nanosecond X-ray photon correlation spectroscopy using pulse time structure of a storage-ring source

X-ray photon correlation spectroscopy (XPCS) is a routine technique to study slow dynamics in complex systems at storage-ring sources. Achieving nanosecond time resolution with the conventional XPCS technique is, however, still an experimentally challenging task requiring fast detectors and sufficient photon flux. Here, the result of a nanosecond XPCS study of fast colloidal dynamics is shown by employing an adaptive gain integrating pixel detector (AGIPD) operated at frame rates of the intrinsic pulse structure of the storage ring. Correlation functions from single-pulse speckle patterns with the shortest correlation time of 192 ns have been calculated. These studies provide an important step towards routine fast XPCS studies at storage rings

Characterization of the AGIPD1.1 readout chip and improvements with respect to AGIPD1.0

AGIPD, the Adaptive Gain Integrating Pixel Detector, is a hybrid detector with a frame rate of 4.5 , a dynamic range up to 12.4 photons, as well as single photon resolution, developed for the European XFEL (Eu.XFEL). The final 1 Mpixel detector system consists of 16 tiled modules each one with 16 readout chips. The single ASIC is 64 x 64 pixels, each with a size of 200 x 200 . Each pixel can store up to 352 images. This work is focused on the characterization of AGIPD1.1, the second version of the full scale ASIC, and the improvements with respect to AGIPD1.0. From the measurements presented in this paper we show that the flaws observed in AGIPD1.0 (i.e. ghosting, crosstalk, slow readout speed) have been fixed in AGIPD1.1. In addition the main performance parameters such as noise, dynamic range and so on were measured for the new version of the ASIC and will be summarized