Undistorted X-ray Absorption Spectroscopy Using s-Core-Orbital Emissions.
Detection of secondary emissions, fluorescence yield (FY), or electron yield (EY), originating from the relaxation processes upon X-ray resonant absorption has been widely adopted for X-ray absorption spectroscopy (XAS) measurements when the primary absorption process cannot be probed directly in transmission mode. Various spectral distortion effects inherent in the relaxation processes and in the subsequent transportation of emitted particles (electron or photon) through the sample, however, undermine the proportionality of the emission signals to the X-ray absorption coefficient. In the present study, multiple radiative (FY) and nonradiative (EY) decay channels have been experimentally investigated on a model system, FeCl3 aqueous solution, at the excitation energy of the Fe L-edge. The systematic comparisons between the experimental spectra taken from various decay channels, as well as the comparison with the theoretically simulated Fe L-edge XA spectrum that involves only the absorption process, indicate that the detection of the Fe 3s → 2p partial fluorescence yield (PFY) gives rise to the true Fe L-edge XA spectrum. The two key characteristics generalized from this particular decay channel-zero orbital angular momentum (i.e., s orbital) and core-level emission-set a guideline for obtaining undistorted X-ray absorption spectra in the future.
Institute of Methods for Material Development, Helmholtz-Zentrum Berlin für Materialien und Energie (HZB) , Albert-Einstein-Strasse 15, D-12489 Berlin, Germany.|Department of Chemistry, Free University Berlin , Takustrasse 3, 14195 Berlin, Germany.
Ronny
R
Golnak
Institute of Methods for Material Development, Helmholtz-Zentrum Berlin für Materialien und Energie (HZB) , Albert-Einstein-Strasse 15, D-12489 Berlin, Germany.
Jie
J
Xiao
Institute of Methods for Material Development, Helmholtz-Zentrum Berlin für Materialien und Energie (HZB) , Albert-Einstein-Strasse 15, D-12489 Berlin, Germany.|Department of Physics, Free University Berlin , Arnimallee 14, 14195 Berlin, Germany.
Kaan
K
Atak
Institute of Methods for Material Development, Helmholtz-Zentrum Berlin für Materialien und Energie (HZB) , Albert-Einstein-Strasse 15, D-12489 Berlin, Germany.
Isaak
I
Unger
Institute of Methods for Material Development, Helmholtz-Zentrum Berlin für Materialien und Energie (HZB) , Albert-Einstein-Strasse 15, D-12489 Berlin, Germany.
Robert
R
Seidel
Institute of Methods for Material Development, Helmholtz-Zentrum Berlin für Materialien und Energie (HZB) , Albert-Einstein-Strasse 15, D-12489 Berlin, Germany.
Bernd
B
Winter
Institute of Methods for Material Development, Helmholtz-Zentrum Berlin für Materialien und Energie (HZB) , Albert-Einstein-Strasse 15, D-12489 Berlin, Germany.|Department of Physics, Free University Berlin , Arnimallee 14, 14195 Berlin, Germany.
Emad F
EF
Aziz