International
Tables for
Crystallography
Volume H
Powder diffraction
Edited by C. J. Gilmore, J. A. Kaduk and H. Schenk
International Tables for Crystallography (2018). Vol. H, ch. 3.1, p. 226

Table 3.1.1 

J. P. Cline,a* M. H. Mendenhall,a D. Black,a D. Windovera and A. Heninsa

aNational Institute of Standards and Technology, Gaithersburg, Maryland, USA
Correspondence e-mail:  james.cline@nist.gov

Table 3.1.1| top | pdf |
Aberrations comprising the geometric component of the IPF

AberrationControlling parametersImpact
X-ray source width (wx) Angle subtended by source: wx/R Symmetric broadening
Receiving-slit width or PSD strip width (wr) Angle subtended by slit/strip: wr/R Symmetric broadening
Flat specimen error/equatorial divergence Angle of divergence slit: α Asymmetric broadening to low 2θ, with decreasing 2θ
PSD defocusing PSD window width, angle of divergence slit: α Symmetric broadening with 1/(tan θ)
Axial divergence   Below ∼ 100°:
 Case 1: no Soller slits Axial lengths of the X-ray source (Lx), sample (Ls) and receiving slit (Lr) relative to goniometer radius (R) asymmetric broadening to low 2θ, with decreasing 2θ
 Case 2: Soller slits define divergence angle Acceptance angles ΔI and ΔD of the incident- and diffracted-beam Soller slits else to high 2θ, with increasing 2θ
Specimen transparency Penetration factor relative to diffractometer radius 1/μR Asymmetric broadening to low 2θ, with sin(2θ)
Specimen displacement z height Displacement of specimen surface from goniometer rotation axes Displacement of profiles with cos θ