Diffraction by nanocrystals

• Published in: Journal of the Optical Society of America. A, Optics, image science, and vision Vol. 30; no. 12; p. 2627
• Main Authors: Chen, Joe P J, Millane, Rick P
• Format: Journal Article
• Language: English
• Published: United States 01.12.2013
• Subjects: Algorithms; Computer Simulation; Crystallography, X-Ray - methods; Image Processing, Computer-Assisted; Lasers; Monte Carlo Method; Nanoparticles - chemistry; Nanotechnology - methods; X-Ray Diffraction
• ISSN: 1520-8532
• DOI: 10.1364/JOSAA.30.002627

X-ray femtosecond nanocrystallography is a new, potentially powerful technique for imaging biological macromolecules that uses ensemble-averaged measurements of diffraction of x-ray free-electron laser pulses from nanocrytalline specimens. Nanocrystals have some diffraction characteristics that are distinct from those of macroscopic crystals, due to the presence of different kinds of unit cell in the crystal and of truncated unit cells on the crystal surface. Expressions are derived for diffraction by nanocrystals with variable and incomplete unit cells, averaged over a distribution of crystal sizes and shapes. The diffraction contains differently modulated Bragg components that are due to interference effects within and between the full and incomplete unit cells. Estimates are obtained for the relative magnitudes of the components. The nature of the diffraction is illustrated by two-dimensional simulations. Implications for molecular imaging are discussed.