The knowledge of atomic fundamental parameters such as mass attenuation coecients with low uncertainties, is of decisive importance in elemental quantication using X-ray uorescence analysis techniques. Several databases are accessible and frequently used within a large community of users. These compilations are most often in good agreement for photon energies in the hard X-ray ranges. However, they signicantly dier for low photon energies and around the absorption edges of any element. In a joint cooperation of the metrology institutes of France and Germany, mass attenuation coecients of copper and zinc were determined experimentally in the photon energy range from 100 eV to 30 keV by independent approaches using monochromatized synchrotron radiation at SOLEIL (France) and BESSY II (Germany), respectively. The application of high-accuracy experimental techniques resulted in mass attenuation coecient datasets determined with low uncertainties that are directly compared to existing databases. The novel datasets are expected to enhance the reliability of mass attenuation coecients.
It has been previously shown that two effects cause dramatic changes in the x-ray absorption and emission spectra from the N K edge of the insulating crystal ammonium nitrate. First, vibrational disorder causes major changes in the absorption spectrum, originating not only from the thermal population of phonons, but, significantly, from zero-point motion as well. Second, the anomalously large broadening (~ 4 eV) of the emission originating from nitrate σ states is due to unusually short lifetimes of quasiparticles in an otherwise extremely narrow band. In this work we investigate the coupling of these effects to core and valence excitons that are created as the initial x-ray excitation energy is progressively reduced toward the N edge. Using a GW/Bethe-Salpeter approach, we show the extent to which this anomalous broadening is captured by the GW approximation. The data and calculations demonstrate the importance that the complex self-energies (finite lifetimes) of valence bands have on the interpretation of emission spectra. We produce a scheme to explain why extreme lifetimes should appear in σ states of other similar compounds.
The determination of the thickness and elemental composition is an important part of the characterization of nanolayered structures. For buried nanolayers, X-ray fluorescence spectrometry is a qualified method for the thickness determination whereas conventional electron emission based methods may reach their limits due to rather restricted information depths. The aim of the presented investigation was the comparison of reference-free X-ray fluorescence spectrometry under conventional and grazing incidence conditions offering complementary information with respect to quantification reliability, elemental sensitivity, and layer sequences. For this purpose, buried boron-carbon layers with nominal thicknesses of 1, 3, and 5 nm have been studied using monochromatized undulator radiation in the laboratory of the Physikalisch-Technische Bundesanstalt (PTB) at the synchrotron radiation facility BESSY II. The results for the two beam geometries are compared and show particulate good agreements, thus encouraging the complementary use of both methodologies.
Improvement in the performance of functional nanoscaled devices involves novel materials, more complex structures, and advanced technological processes. The transitions to heavier elements and to thicker layers restrict access to the chemical and physical characterization of the internal material interfaces. Conventional nondestructive characterization techniques such as X-ray photoelectron spectroscopy suffer from sensitivity and quantification restrictions whereas destructive techniques such as ion mass spectrometry may modify the chemical properties of internal interfaces. Thus, novel methods providing sufficient sensitivity, reliable quantification, and high information depths to reveal interfacial parameters are needed for R&D challenges on the nanoscale. Measurement strategies adapted to nanoscaled samples enable the combination of Near-Edge X-ray Absorption Fine Structure and Grazing Incidence X-ray Fluorescence to allow for chemical nanometrology of internal material interfaces. Their validation has been performed at nanolayered model structures consisting of a silicon substrate, a physically vapor deposited Ni metal layer, and, on top, a chemically vapor deposited B(x)C(y)N(z) light element layer.
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