Open AccessThe minimum crystal size needed for a complete diffraction data set
Author(s) -
Holton James M.,
Frankel Kenneth A.
Publication year - 2010
Publication title -
acta crystallographica section d
Language(s) - English
Resource type - Journals
ISSN - 1399-0047
DOI - 10.1107/s0907444910007262
Subject(s) - diffraction , scattering , photon , optics , crystal (programming language) , compton scattering , attenuation , computational physics , anomalous scattering , detector , physics , noise (video) , wavelength , resolution (logic) , materials science , molecular physics , computer science , image (mathematics) , programming language , artificial intelligence
In this work, classic intensity formulae were united with an empirical spot‐fading model in order to calculate the diameter of a spherical crystal that will scatter the required number of photons per spot at a desired resolution over the radiation‐damage‐limited lifetime. The influences of molecular weight, solvent content, Wilson B factor, X‐ray wavelength and attenuation on scattering power and dose were all included. Taking the net photon count in a spot as the only source of noise, a complete data set with a signal‐to‐noise ratio of 2 at 2 Å resolution was predicted to be attainable from a perfect lysozyme crystal sphere 1.2 µm in diameter and two different models of photoelectron escape reduced this to 0.5 or 0.34 µm. These represent 15‐fold to 700‐fold less scattering power than the smallest experimentally determined crystal size to date, but the gap was shown to be consistent with the background scattering level of the relevant experiment. These results suggest that reduction of background photons and diffraction spot size on the detector are the principal paths to improving crystallographic data quality beyond current limits.