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Energy‐dispersive phase plate for magnetic circular dichroism experiments in the X‐ray range
Author(s) -
Giles C.,
Malgrange C.,
Goulon J.,
De Bergevin F.,
Vettier C.,
Dartyge E.,
Fontaine A.,
Giorgetti C.,
Pizzini S.
Publication year - 1994
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889893007976
Subject(s) - optics , spectrometer , magnetic circular dichroism , circular polarization , collimated light , x ray magnetic circular dichroism , photon energy , physics , spectral line , photon , laser , astronomy , microstrip
A 220 diamond phase plate was combined with an energy‐dispersive absorption spectrometer to convert linearly polarized X‐rays into circularly polarized photons and to detect circular magnetic X‐ray dichroism (CMXD) from ferromagnetic samples. In these experiments, carried out at LURE, the energy‐dispersive spectrometer was equipped with a bent Si (311) polychromator and vertically collimating slits accepting essentially a linearly polarized incident beam. The quarter‐wave plate was operated in the Bragg geometry but well outside the range of quasi total reflection, with the consequence that the forward‐diffracted beam was circularly polarized with a polarization rate approaching 80% over the whole energy bandpass of the polychromator. CMXD spectra of GdFe 2 and GdCo 2 intermetallic compounds were recorded at ca 7.2 keV near the Gd L III absorption edge: they are essentially identical to the spectra commonly recorded with elliptically polarized X‐ray photons collected out of the orbit plane of the storage ring. It is suggested that the energy‐dispersive phase plate will be very useful to detect CMXD spectra with energy‐dispersive spectrometers exploiting the well collimated linearly polarized emission of standard undulators installed on the storage rings of the third generation.