A preferred orientation correction to describe a fiber texture under glancing incidence

Simeone, D.; Gosset, D.; Baldinozzi, G.

doi:10.1107/S0021889812045736

Figure 1
Schematic description of a powder scan in asymmetric diffraction conditions. The sample frame is determined by the three orthonormal vectors $[{\bf X}_{\rm S}]$ , $[{\bf Y}_{\rm S}]$ and $[{\bf Z}_{\rm S}]$ . The vector $[{\bf Z}_{\rm S}]$ is normal to the surface of the sample. The scattering plane is defined by the incident wavevector $[{\bf k}_{\rm inc}}]$ and the $[{\bf Z}_{\rm S}]$ vector. The incidence angle $[\alpha]$ is the angle between $[{\bf k}_{\rm inc}}]$ and the $[{\bf Y}_{\rm S}]$ vector lying on the surface of the sample. In asymmetric scattering geometry, the scattering vector $[{\bf q}_{hkl}}]$ associated with the hkl reflection is in general not parallel to $[{\bf Z}_{\rm S}]$ . The angle $[\omega_{hkl}]$ between these two vectors, lying in the scattering plane, is equal to $[({{2\theta_{hkl}} / {2}}-\alpha)]$ , where $[2\theta_{hkl}]$ is the Bragg angle associated with the hkl reflection. Only a small part of the diffracted intensity along the Debye-Scherrer ring (solid circle; red in the electronic version of the journal) is collected by the detector.