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Methoden und Instrumentierung Poster: Mi., 14:00–16:30 M-P57
Absolute determination of resonant Raman scattering cross sections for
silicon
Matthias Müller 1 , Birgit Kanngießer 2 , Burkhard Beckhoff 1 , Gerhard
Ulm 1
1 Physikalisch-Technische Bundesanstalt, Abbestraße 2-12, 10587 Berlin – 2 Technische
Universität Berlin, Hardenbergstr. 36, 10623 Berlin
The resonant Raman scattering (RRS) of X-rays in the vicinity of the K-absorption
edge of silicon was studied. The investigation was carried out at the plane grating
monochromator beamline for undulator radiation of the PTB laboratory at BESSY
II in Berlin. Cross sections were determined absolutely [1] for a wide energy range of
incident photons with small relative uncertainties employing calibrated instrumentation
avoiding any reference samples. The experimentally determined values differ clearly
from the theoretical ones found in the literature.
This work was motivated by the disturbing continuous background a substrate or
a matrix element can produce in total reflection x-ray fluorescence analysis (TXRF)
and x-ray fluorescence analysis (XRF). That background can affect dramatically the
lower limits of detection for trace elements with fluorescence lines below the resonant
absorption edge of a matrix or a substrate element. One example is the detection of
Al and Mg on silicon wafers, where the incident radiation with photon energy below
the silicon K-edge is resonantly scattered at the silicon 2p electrons. For reference-free
quantitative analysis by either TXRF or XRF the knowledge of the cross sections for
the RRS is important for the correct background calculation.
[1] M. Müller, B. Beckhoff, G. Ulm, and B. Kanngießer, Phys. Rev. A (2006) accepted
[2] C.Streli et al., Spectrochim. Acta B 58 (2003) 2113
[3] M. Kolbe, B. Beckhoff, M. Krumrey, G. Ulm, Spectrochim. Acta B 60 (2005) 505