R A Gordon et al 2009 J. Phys.: Conf. Ser. 190 012047 doi:10.1088/1742-6596/190/1/012047
R A Gordon1, M W Haverkort2, Subhra Sen Gupta3 and G A Sawatzky3
Show affiliationsInformation on valence orbitals and electronic interactions in single crystal systems can be obtained through orientation-dependent x-ray measurements, but this can be problematic for a cubic system. Polarisation-dependent x-ray absorption measurements are common, but are dominated by dipole transitions which, for a cubic system, are isotropic even though a cubic system is not. Many edges, particularly for transition metals, do have electric quadrupole features that could lead to dichroism but proximity to the dipole transition can make interpretation challenging. X-ray Raman Spectroscopy (XRS) can also be used to perform orientation-dependent near-edge measurements – not only dependent on the direction of the momentum transfer but also its magnitude, q. Previous XRS measurements on polycrystalline materials revealed that multipole (higher order than dipole) transitions are readily observable in the pre-threshold region of rare earth N4,5 edges, actually replacing the dipole at high-q. We have extended these studies to examine orientation-dependent XRS for CeO2 and MnO single crystals, as prototype systems for theoretical treatment. Dichroism is observed at both the Ce N4,5 and Mn M2,3 edges in these cubic materials.
78.30.Hv Other nonmetallic inorganics
Issue 1 (2009)
R A Gordon et al 2009 J. Phys.: Conf. Ser. 190 012047
I A Buyanova et al 2006 J. Phys.: Condens. Matter 18 449
P. Kharb et al. 2006 ApJ 652 177
Tetsuya Takeuchi et al 2002 J. Phys.: Condens. Matter 14 L261
F Merola et al 2009 J. Micromech. Microeng. 19 125006
C P Ballance and D C Griffin 2004 J. Phys. B: At. Mol. Opt. Phys. 37 2943
A Ślebarski et al 2006 J. Phys.: Condens. Matter 18 10319
R Kramer et al 2005 Phys. Med. Biol. 50 3681
G. Risaliti et al. 1999 ApJ 522 157
David Garfinkle and Carsten Gundlach 1999 Class. Quantum Grav. 16 4111