Accurate experimental determination of gallium K- and L3-shell XRF fundamental parameters

The fluorescence yield of the K- and L3-shell of gallium was determined using the radiometrically calibrated (reference-free) X-ray fluorescence instrumentation at the BESSY II synchrotron radiation facility. Simultaneous transmission and fluorescence signals from GaSe foils were obtained, resulting in K- and L3-shell fluorescence yield values consistent with existing database values(omega_Ga_K=0.515 +- 0.019, omega_Ga_L3=0.013 +- 0.001). For the first time, these standard combined uncertainties are obtained from a properly constructed Uncertainty Budget. These K-shell fluorescence yield values support Bambynek's semi-empirical compilation from 1972: these and other measurements yield a combined recommended value of omega_Ga_K=0.514 +- 0.010. Using the measured fluorescence yields together with production yields from reference Ga-implanted samples where the quantity of implanted Ga was determined at 1.3% traceable accuracy by Rutherford backscattering spectrometry, the K-shell and L3-subshell photoionization cross sections at selected incident photon energies were also determined and compared critically with the standard databases.Comment: 17 pages, 6 figure

Titanium and titanium oxides at the K- and L-edges: validating theoretical calculations of X-ray absorption and X-ray emission spectra with measurements

Using well-calibrated experimental data we validate theoretical X-ray absorption spectroscopy (XAS) as well as X-ray emission spectroscopy (XES) calculations for titanium (Ti), titanium oxide (TiO), and titanium dioxide (TiO$_2$) at the Ti K- and L-edges as well as O K-edge. XAS and XES in combination with a multi-edge approach offer a detailed insight into the electronic structure of materials since both the occupied and unoccupied states, are probed. The experimental results are compared with ab initio calculations from the OCEAN package which uses the Bethe-Salpeter equation (BSE) approach. Using the same set of input parameters for each compound for calculations at different edges, the transferability of the OCEAN calculations across different spectroscopy methods and energy ranges is validated. Thus, the broad applicability for analysing and interpreting the electronic structure of materials with the OCEAN package is shown

Experimental determination of X-ray atomic fundamental parameters of nickel

Abstract X-ray atomic properties of Nickel were investigated in a singular approach that combines different experimental techniques to obtain new and useful reliable values of atomic fundamental parameters for X-ray spectrometric purposes and for comparison to theoretical predictions. We determined the mass attenuation coefficients in an energy range covering the L- and K- absorption edges, the K-shell fluorescence yield and the Kb/Ka and Kb1,3/Ka1,2 transition probability ratios. The obtained line profiles and linewidths of the Ka and Kb transitions in Ni can be considered as the contribution of the satellite lines arising from the [KM] shake processes suggested by Deutsch et al. [1] and Ito et al. [2]. Comparison of the new data with several databases showed a good agreement but also discrepancies were found with existing tabulated values

Theoretical and experimental determination of LL-shell decay rates, line widths, and fluorescence yields in Ge

Fluorescence yields (FYs) for the Ge L shell were determined by a theoretical and two experimental groups within the framework of the International Initiative on X-Ray Fundamental Parameters Collaboration. Calculations were performed using the Dirac-Fock method, including relativistic and QED corrections. The experimental value of the L3FYωL3 was determined at the Physikalisch-Technische Bundesanstalt undulator beamline of the synchrotron radiation facility BESSY II in Berlin, Germany, and the Lα1,2 and Lβ1 line widths were measured at the Swiss Light Source, Paul Scherrer Institute, Switzerland, using monochromatized synchrotron radiation and a von Hamos x-ray crystal spectrometer. The measured fluorescence yields and line widths are compared to the corresponding calculated values

Grazing incidence x ray fluorescence analysis for non destructive determination of In and Ga depth profiles in Cu In,Ga Se2 absorber films

Development of highly efficient thin film solar cells involves band gap engineering by tuning their elemental composition with depth. Here we show that grazing incidence X ray fluorescence GIXRF analysis using monochromatic synchrotron radiation and well characterized instrumentation is suitable for a non destructive and reference free analysis of compositional depth profiles in thin films. Variation of the incidence angle provides quantitative access to the in depth distribution of the elements, which are retrieved from measured fluorescence intensities by modeling parameterized gradients and fitting calculated to measured fluorescence intensities. Our results show that double Ga gradients in Cu In1 x,Gax Se2 can be resolved by GIXR

Efficient high-resolution X-ray emission spectrometry using synchrotron radiation

Das Ziel der vorliegenden Arbeit bestand darin, durch die Erhöhung der Sensitivität eines wellenlängendispersiven Spektrometers (WDS) im Spektralbereich weicher Röntgenstrahlung Zugang zu hochauflösender Röntgenemissionsspetrometrie an nanoskaligen Materialien leichter Elemente und Übergangsmetallen zu erhalten. Die Erhöhung der Sensitivität wurde durch eine Refokussierung der anregenden Undulatorstrahlung erreicht. Mit der erhöhten Sensitivität des WDS konnten zum einen die chemischen Spezies verschiedener, nominell 100 nm dicker Titanoxide ermittelt werden. Die Kombination aus Refokussieroptik und kalibriertem Spektrometer ermöglichte zum anderen die Detektion und Entfaltung der L-Fluoreszenzlinien von nanoskaligen Titanoxiden. Mit der Kalibrierung des Spektrometers wurde eine zuverlässige Bestimmung der bindungsabhängigen Übergangswahrscheinlichkeiten der Titan La- und Ll-Fluoreszenzlinien erreicht. Die Bestimmung der Übergangswahrscheinlichkeit in Abhängigkeit des Bindungszustandes wurde bisher nach bestem Wissen im Spektralbereich weicher Röntgenstrahlung noch nicht durchgeführt. Die Güte der Refokussierung wurde durch verschiedene Diagnostik charakterisiert. Es konnten vertikale Halbwertsbreiten von ca. 10 µm bis 20 µm und horizontale Halbwertsbreiten von ca. 12 µm bis 25 µm über ein Energiebereich von 180 eV bis 1310 eV erreicht werden. Über kalibrierte Photodioden war es möglich, sowohl die effektive Transmission der Monokapillare zu bestimmen, als auch den absoluten Photonenfluss zu überwachen. Es konnte mit Hilfe der Refokussierung experimentell eine Erhöhung des Photonenflusses um den Faktor von 4.9 erreicht werden. Durch die Erhöhung des Photonenflusses ist es möglich, nanoskaligen Materialien zu untersuchen. Anhand der Bestimmung der Nachweisgrenze von Bor Ka und Titan La konnte gezeigt dies werden. In beiden Fällen wurde eine Nachweisgrenze von 0.4 nm äquivalenter Schichtdicke (rund 1*10-7 g/cm2 bis 2*10-7 g/cm2 bzw. 3*1015 Atome/cm2 bis 5*1015 Atome/cm2). Mit dem um die Refokussierung erweiterten WDS wurde Röntgenemissionsspektrometrie an verschiedenen Titanoxiden durchgeführt. Dabei konnte die chemische Bindung anhand der hochauflösenden Röntgenemissionsspektren identifiziert werden. Zusätzlich zur Bestimmung des Bindungszustandes wurde resonante Röntgenemissionsspektroskopie durchgeführt, mit der im Prinzip Informationen über die besetzten und unbesetzten Elektronenzustände der Valenzelektronen gewonnen werden können. Um eine quantitative Analyse der Titan L-Fluoreszenzlinien durchzuführen, musste das WDS kalibriert werden. Dazu wurde das Ansprechverhalten des Spektrometers durch direkte Undulatorstrahlung experimentell bestimmt und mittels einer Modellfunktion für das Ansprechverhalten die Ansprechfunktionen für den gesamten erfassten Energiebereich modelliert und parametrisiert. Mit ihnen können die Emissionsspektren zuverlässig entfaltet werden und sie erlauben damit eine genaue Bestimmung der Fluoreszenzintensitäten. Die relativen Unsicherheiten der Intensitäten werden in dieser Arbeit mit ca. 15 % abgeschätzt. Es wurden die Übergangswahrscheinlichkeit der Titan L3-Fluoreszenzlinien in Abhängigkeit des Bindungszustandes bestimmt. Für metallisches Titan beträgt die Übergangswahrscheinlichkeit für die Titan Ll-Fluoreszenzlinie 0.59(6) und fällt dann mit steigendem Oxidationszustand ab. Bei Titandioxid beträgt die Übergangswahrscheinlichkeit für die Titan Ll-Fluoreszenzlinie lediglich 0.46(7).The aim of the present work is to get access to high-resolution X-Ray Emission Spectrometry (XES) at nanoscaled materials, consisting of light elements and transition metals, by the increase of the sensitivity of a Wavelength-Dispersive Spectrometer (WDS) in the soft X-Ray range. The increase of the sensitivity was achieved by a refocusing of the incident radiation. With the increased sensitivity of the WDS, it was possible to determine the chemical species of different, nominal 100 nm thin titanium oxides. The combination of the refocusing optic and calibrated spectrometer enabled the detection and deconvolution of the L-fluorescence radiation of these nanoscaled titanium oxides. Due to the calibration of the spectrometer, a reliable determination of the transition probabilities of the titanium La- and Ll-fluorescence lines as a function of the chemical state is possible. To the best of my knowledge, the determination of the transition probabilities as a function of the chemical state in the soft X-Ray range has not been investigated yet. The quality of the refocusing was characterized using different diagnostic tools. Vertical full width at half maximum (FWHM) values of the focused beam between 10 µm to 20 µm and horizontal FWHM values between 12 µm and 25 µm could be achieved over an energy range of 180 eV to 1310 eV. Using calibrated photodiodes, it was possible to determine the absolute transmission of the used single bounce monocapillary as well as to monitor the absolute photon flux. By means of the refocusing, it was possible to increase the photon flux by a factor of 4.9 experimentally. The increase of the photon flux enables the analysis of nanoscaled materials with the used spectrometer. This could be shown based on the determination of the lower limit of detection of boron Ka and titanium La. In both cases, the lower limit of detection of 0.4 nm equivalent layer thickness was achieved (about 1*10-7 g/cm2 to 2*10-7 g/cm2 or 3*1015 atoms/cm2 to 5*1015 atoms/cm2 , respectively). With the spectrometer extended by the refocusing, XES at different titanium oxides could be performed. Using the high-resolution XES, the chemical species of the different titanium oxides could be identified. In addition to the chemical speciation, it is now possible to do Resonance Inelastic X-Ray Scattering (RIXS). With this method, information about the occupied and unoccupied electronic states of the valence electrons can be revealed. For a quantitative analysis of the titanium L-fluorescence lines, the WDS had to be calibrated. For this purpose, the response behavior of the spectrometer was experimental determined using direct undulator radiation. By means of a model function for the response behavior, the response functions could be modeled and parameterized for the whole covered energy range. The response functions lead to a reliable deconvolution of the emission spectra and thereby allow an accurate determination of the fluorescence intensities. In this work, the relative uncertainties of the intensities are estimated with about 15 %. The transition probabilities of the titanium L3-fluorescence lines were determined as a function of the chemical state. For metallic titanium, the transition probability of the titanium Ll-fluorescence line amounts to 0.59(6) and decreases with increasing oxidation state of the titanium. For titanium dioxide, the transition probability of the titanium Ll-fluorescence line only amounts to 0.46(7)