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GIXRF

GIXRF

In X-ray fluorescence analysis, electrons from inner atomic shells are excited by incident X-ray photons. The subsequent decay of these excited states leads to the emission of element-specific X-ray fluorescence radiation. Quantitative conclusions about the material composition can be drawn by an energy-selective measurement of the X-ray fluorescence intensities using calibrated instrumentation. By means of a grazing incidence of the excitation X-rays on the sample (GIXRF), depth-dependent element distributions can also be determined with this method.
For periodic nanostructures it is possible to generate a standing wave field surrounding the structure. By rotating the lattice structure around two axes with respect to the incident X-ray beam, this interference between the incident and the outgoing wave can be used to vary the locations of maximum electric field strength within the structure and thus scan the nanostructure with a sub-nm resolution. The intensity of the resulting fluorescence radiation is proportional to the excitation electric field strength in the medium. The evaluation of the data therefore requires a numerical modeling of the spatial field strength distribution. A finite element method can be used in the simulation for line grating structures. For 3D structures, however, the numerical effort for the short wavelengths is so high that a rigorous calculation of the near fields is hardly possible. However, approximation methods such as MB-DDT can close this gap (see numerical simulations).
At PTB PGM Beamline at BESSY II, GIXRF experiments can be performed in an energy range from 80 eV to 1860 eV. A calibrated Silicon Drift Detector (SDD) is available for the energy dispersive detection of the emitted fluorescence radiation. A 2-axis goniometer can be used to adjust the samples in ultra-high vacuum. The angle of incidence can be aligned with an accuracy of less than 0.01°.
Further information can be found under   [Opens external link in current window7.24 Röntgenspektrometrie].

 

PGM Beamline
Energy range:80 eV - 1.86 keV
Photon flux: 10^10 / s
Beam waist:40 mm x 140 mm
Divergence:0.03°
Energy resolution:10^-4
Preferred sample sizes:20 mm x 20 mm

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