Total reflection X-ray fluorescence (TXRF) analysis is a well-established method to monitor lowest level contamination on semiconductor surfaces. Even light elements on a wafer surface can be excited effectively when using high-flux synchrotron radiation in the soft X-ray range. To meet current industrial requirements in nondestructive semiconductor analysis, the Physikalisch-Technische Bundesanstalt (PTB) operates dedicated instrumentation for analyzing light element contamination on wafer pieces as well as on 200- and 300-mm silicon wafer surfaces. This instrumentation is also suited for grazing incidence X-ray fluorescence analysis and conventional energy-dispersive X-ray fluorescence analysis of buried and surface nanolayered structures, respectively. The most prominent features are a high-vacuum load-lock combined with an equipment front end module and a UHV irradiation chamber with an electrostatic chuck mounted on an eight-axis manipulator. Here, the entire surface of a 200- or a 300-mm wafer can be scanned by monochromatized radiation provided by the plane grating monochromator beamline for undulator radiation in the PTB laboratory at the electron storage ring BESSY II. This beamline provides high spectral purity and high photon flux in the range of 0.078-1.86 keV. In addition, absolutely calibrated photodiodes and Si(Li) detectors are used to monitor the exciting radiant power respectively the fluorescence radiation. Furthermore, the footprint of the excitation radiation at the wafer surface is well-known due to beam profile recordings by a CCD during special operation conditions at BESSY II that allow for drastically reduced electron beam currents. Thus, all the requirements of completely reference-free quantitation of TXRF analysis are fulfilled and are to be presented in the present work. The perspectives to arrange for reference-free quantitation using X-ray tube-based, table-top TXRF analysis are also addressed.

A new single crystal from isotopically enriched silicon was used to determine the Avogadro constant N A by the x-ray-crystal density method. The new crystal, named Si28-23Pr11, has a higher enrichment than the former 'AVO28' crystal allowing a smaller uncertainty of the molar mass determination. Again, two 1 kg spheres were manufactured from this crystal. The crystal and the spheres were measured with improved and new methods. One sphere, Si28kg01a, was measured at NMIJ and PTB with very consistent results. The other sphere, Si28kg01b, was measured only at PTB and yielded nearly the same Avogadro constant value. The mean result for both 1 kg spheres is N A = 6.022 140 526(70) × 10 23 mol −1 with a relative standard uncertainty of 1.2 × 10 −8 . This value deviates from the Avogadro value published in 2015 for the AVO28 crystal by about 3.9(2.1) × 10 −8 . Possible reasons for this difference are discussed and additional measurements are proposed.

To search for the lowest energy nuclear isomeric transition in 229 Th in solid samples, a novel adsorption technique which prepares 229 Th atoms on a surface of CaF 2 is developed. Adsorbed 229 Th is exposed to highly intensive undulator radiation in the wavelength range between 130 and 320 nm, which includes the indirectly measured nuclear resonance wavelength 160(10) nm. After the excitation, fluorescence from the sample is detected with a VUV sensitive photomultiplier tube. No clear signal relating to the nuclear transition is observed and possible reasons are discussed.

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Photon-in/photon-out experiments at thin specimens have been carried out to determine L-subshell fluorescence yields as well as Coster-Kronig transition probabilities of Au, Pb, Mo, and Pd using radiometrically calibrated instrumentation in the Physikalisch-Technische Bundesanstalt (PTB) laboratory at the electron storage ring BESSY II in Berlin. An advanced approach was developed in order to derive the fluorescence line intensities by means of line sets of each subshell that were corrected for self-absorption and broadened with experimentally determined detector response functions. The respective photoelectric cross sections for each subshell were determined by means of transmission measurements of the same samples without any change in the experimental operating condition. All values derived were compared to those of earlier works. A completely traceable uncertainty budget is provided for the determined values.The complete understanding of atomic excitation and emission processes as well as the exact knowledge of related cross sections are crucial for quantitative investigations of elemental concentrations in unknown specimens by x-ray spectrometry. The emitted spectral response of an unknown sample following the excitation by x rays is based on both the specimen's elemental composition and the related atomic processes, the probability of which depends on a set of atomic fundamental parameters. For the quantitative determination of the respective elemental concentrations, the cross sections for photoionization of the (sub)shell and for both elastic and inelastic scattering, the related fluorescence yield, and transition probabilities associated with the specific inner-shell excitations have to be exactly known. Therefore, the uncertainty of these fundamental parameters is relevant for reference-based as well as reference-free x-ray fluorescence analysis results. Here, a reliable uncertainty budget is needed [1-3].Krause et al.[4] estimated relative uncertainties by comparing of theoretical total photoionization cross sections with those determined experimentally, which have still mostly remained valid since the late 1970's [5]. In addition, one may assume that most of the relative uncertainties are estimated rather from the compilation of available data than from the individual experimental uncertainty budget. An example of a compilation-based uncertainty indication is the compilation of theoretical data by Puri et al. published in 1993 for elements 25 Z 96 based on the relativistic Dirac-Hartree-Slater model [6], which states only a fitting error of 2% for elements with higher Z.The fluorescence yields as well as Coster-Kronig (CK) transition probabilities were investigated in earlier works, e.g., by electron-induced high-resolution x-ray fluorescence spectroscopy, Kα-Lα-coincidence methods [7]. When monochromatic tunable synchrotron radiation became available, photoionization experiments were also carried out, but the respective relative uncertainties could not be reduced significantly [5]. This was partially...