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A unified formulation of dichroic signals using the Borrmann effect and twisted photon beams

DOI: 10.1038/s41598-018-23627-5 DOI Help

Authors: Stephen P. Collins (Diamond Light Source) , Stephen W. Lovesey (Diamond Light Source; ISIS Facility)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Scientific Reports , VOL 8

State: Published (Approved)
Published: May 2018

Open Access Open Access

Abstract: Dichroic X-ray signals derived from the Borrmann effect and a twisted photon beam with topological charge lā€‰=ā€‰1 are formulated with an effective wavevector. The unification applies for non-magnetic and magnetic materials. Electronic degrees of freedom associated with an ion are encapsulated in multipoles previously used to interpret conventional dichroism and Bragg diffraction enhanced by an atomic resonance. A dichroic signal exploiting the Borrmann effect with a linearly polarized beam presents charge-like multipoles that include a hexadecapole. A difference between dichroic signals obtained with a twisted beam carrying spin polarization (circular polarization) and opposite winding numbers presents charge-like atomic multipoles, whereas a twisted beam carrying linear polarization alone presents magnetic (time-odd) multipoles. Charge-like multipoles include a quadrupole, and magnetic multipoles include a dipole and an octupole. We discuss the practicalities and relative merits of spectroscopy exploiting the two remarkably closely-related processes. Signals using beams with topological charges l ā‰„ 2 present additional atomic multipoles.

Journal Keywords: Electronic properties and materials; Theory and computation

Subject Areas: Physics

Technical Areas: Theoretical Physics

Added On: 23/05/2018 10:12


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Physics Theoretical Physics

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