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This content will become publicly available on February 1, 2019

Title: Grating-based holographic diffraction methods for X-rays and neutrons: phase object approximation and dynamical theory

A method dubbed grating-based holography was recently used to determine the structure of colloidal fluids in the rectangular grooves of a diffraction grating from X-ray scattering measurements. Similar grating-based measurements have also been recently made with neutrons using a technique called spin-echo small-angle neutron scattering. The analysis of the X-ray diffraction data was done using an approximation that treats the X-ray phase change caused by the colloidal structure as a small perturbation to the overall phase pattern generated by the grating. In this paper, the adequacy of this weak phase approximation is explored for both X-ray and neutron grating holography. Additionally, it is found that there are several approximations hidden within the weak phase approximation that can lead to incorrect conclusions from experiments. In particular, the phase contrast for the empty grating is a critical parameter. Finally, while the approximation is found to be perfectly adequate for X-ray grating holography experiments performed to date, it cannot be applied to similar neutron experiments because the latter technique requires much deeper grating channels.
Authors:
ORCiD logo [1] ; ORCiD logo [2] ;  [3] ;  [3] ; ORCiD logo [4] ; ORCiD logo [4] ; ORCiD logo [5]
  1. Indiana Univ., Bloomington, IN (United States). Center for Exploration of Energy and Matter and Physics Dept.
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biology and Soft Matter Division
  3. Rutherford Appleton Lab., Oxford (United Kingdom). ISIS Facility
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science
  5. Indiana Univ., Bloomington, IN (United States). Center for Exploration of Energy and Matter and Physics Dept. ; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Neutron Sciences Directorate
Publication Date:
Grant/Contract Number:
AC05-00OR22725; FG02-09ER46279
Type:
Accepted Manuscript
Journal Name:
Journal of Applied Crystallography (Online)
Additional Journal Information:
Journal Name: Journal of Applied Crystallography (Online); Journal Volume: 51; Journal Issue: 1; Journal ID: ISSN 1600-5767
Publisher:
International Union of Crystallography
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 36 MATERIALS SCIENCE; grating-based holography; phase object approximation; dynamical theory
OSTI Identifier:
1422549