Full metadata
Title
Phasing two-dimensional crystal diffraction pattern with iterative projection algorithms
Description
Phase problem has been long-standing in x-ray diffractive imaging. It is originated from the fact that only the amplitude of the scattered wave can be recorded by the detector, losing the phase information. The measurement of amplitude alone is insufficient to solve the structure. Therefore, phase retrieval is essential to structure determination with X-ray diffractive imaging. So far, many experimental as well as algorithmic approaches have been developed to address the phase problem. The experimental phasing methods, such as MAD, SAD etc, exploit the phase relation in vector space. They usually demand a lot of efforts to prepare the samples and require much more data. On the other hand, iterative phasing algorithms make use of the prior knowledge and various constraints in real and reciprocal space. In this thesis, new approaches to the problem of direct digital phasing of X-ray diffraction patterns from two-dimensional organic crystals were presented. The phase problem for Bragg diffraction from two-dimensional (2D) crystalline monolayer in transmission may be solved by imposing a compact support that sets the density to zero outside the monolayer. By iterating between the measured stucture factor magnitudes along reciprocal space rods (starting with random phases) and a density of the correct sign, the complex scattered amplitudes may be found (J. Struct Biol 144, 209 (2003)). However this one-dimensional support function fails to link the rod phases correctly unless a low-resolution real-space map is also available. Minimum prior information required for successful three-dimensional (3D) structure retrieval from a 2D crystal XFEL diffraction dataset were investigated, when using the HIO algorithm. This method provides an alternative way to phase 2D crystal dataset, with less dependence on the high quality model used in the molecular replacement method.
Date Created
2016
Contributors
- Zhao, Yun (Author)
- Spence, John C.H. (Thesis advisor)
- Schmidt, Kevin (Committee member)
- Weierstall, Uwe (Committee member)
- Kirian, Richard (Committee member)
- Zatsepin, Nadia (Committee member)
- Arizona State University (Publisher)
Topical Subject
Resource Type
Extent
viii, 99 pages : illustrations (some color)
Language
eng
Copyright Statement
In Copyright
Primary Member of
Peer-reviewed
No
Open Access
No
Handle
https://hdl.handle.net/2286/R.I.40706
Statement of Responsibility
by Yun Zhao
Description Source
Retrieved on Feb. 20, 2017
Level of coding
full
Note
thesis
Partial requirement for: Ph.D., Arizona State University, 2016
bibliography
Includes bibliographical references (pages 83-87)
Field of study: Physics
System Created
- 2016-12-01 07:00:58
System Modified
- 2021-08-30 01:20:52
- 3 years 2 months ago
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