ORCID Profile
0000-0002-4958-2609
Current Organisation
Massey University
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Publisher: Informa UK Limited
Date: 15-06-2020
Publisher: International Union of Crystallography (IUCr)
Date: 12-10-2020
DOI: 10.1107/S2053273320012188
Abstract: The deterioration of both the signal-to-noise ratio and the spatial resolution in the electron-density distribution reconstructed from diffraction intensities collected at different orientations of a s le is analysed theoretically with respect to the radiation damage to the s le and the variations in the X-ray intensities illuminating different copies of the s le. The simple analytical expressions and numerical estimates obtained for models of radiation damage and incident X-ray pulses may be helpful in planning X-ray free-electron laser (XFEL) imaging experiments and in analysis of experimental data. This approach to the analysis of partially coherent X-ray imaging configurations can potentially be used for analysis of other forms of imaging where the temporal behaviour of the s le and the incident intensity during exposure may affect the inverse problem of s le reconstruction.
Publisher: Informa UK Limited
Date: 04-05-2021
Publisher: International Union of Crystallography (IUCr)
Date: 15-09-2018
DOI: 10.1107/S2052252518010941
Abstract: It is shown that the average signal-to-noise ratio (SNR) in the three-dimensional electron-density distribution of a s le reconstructed by coherent diffractive imaging cannot exceed twice the square root of the ratio of the mean total number of scattered photons detected during the scan and the number of spatially resolved voxels in the reconstructed volume. This result leads to an upper bound on Shannon's information capacity of this imaging method by specifying the maximum number of distinguishable density distributions within the reconstructed volume when the radiation dose delivered to the s le and the spatial resolution are both fixed. If the spatially averaged SNR in the reconstructed electron density is fixed instead, the radiation dose is shown to be proportional to the third or fourth power of the spatial resolution, depending on the s ling of the three-dimensional diffraction space and the scattering power of the s le.
Publisher: International Union of Crystallography (IUCr)
Date: 20-10-2020
DOI: 10.1107/S2052252520013019
Abstract: Resolving the electronic structure of single biological molecules in their native state was among the primary motivations behind X-ray free-electron lasers. The ultra-short pulses they produce can outrun the atomic motion induced by radiation damage, but the electronic structure of the s le is still significantly modified from its original state. This paper explores the decoherence of the scattered signal induced by temporal evolution of the electronic structure in the s le molecule. It is shown that the undamaged electron density of a single-molecule s le can often be retrieved using only the two most occupied modes from the coherent mode decomposition of the partially coherent diffraction fluence.
Publisher: Informa UK Limited
Date: 04-05-2021
Publisher: Informa UK Limited
Date: 13-05-2019
No related grants have been discovered for Andrew Martin.