International
Tables for
Crystallography
Volume F
Crystallography of biological macromolecules
Edited by M. G. Rossmann and E. Arnold

International Tables for Crystallography (2006). Vol. F, ch. 9.1, pp. 177-178   | 1 | 2 |

Section 9.1.4.1. Conventional sources

Z. Dautera* and K. S. Wilsonb

aNational Cancer Institute, Brookhaven National Laboratory, NSLS, Building 725A-X9, Upton, NY 11973, USA, and bStructural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, England
Correspondence e-mail:  dauter@bnl.gov

9.1.4.1. Conventional sources

| top | pdf |

Rotating anodes were initially developed for biological scattering experiments on muscle samples and have the advantage of higher intensity compared to sealed-tube generators. They usually have a copper target providing radiation at a fixed wavelength of 1.542 Å. Alternative targets, such as silver or molybdenum, provide lower intensities at short wavelengths, but have not found general applications to macromolecules. Historically, rotating anodes were first used with nickel filters to give monochromatic Cu Kα radiation. Current systems are equipped with either graphite monochromators, a focusing mirror, or multilayer optics. The latter provide substantially enhanced intensity. Rotating anodes remain the source of choice in most structural biology laboratories. An important choice for the user is in the selection of optimal collimator aperture: this should roughly match the crystal sample dimensions. For large crystals, especially if the cell dimensions are also large, it may be preferable to use collimator settings smaller than the crystal in order to resolve the diffraction spots on the detector. The fine-focus tubes currently being developed may affect the choice of home source over the next years (Arndt, Duncumb et al., 1998[link]; Arndt, Long & Duncumb, 1998[link]).

References

Arndt, U. W., Duncumb, P., Long, J. V. P., Pina, L. & Inneman, A. (1998). Focusing mirrors for use with microfocus X-ray tubes. J. Appl. Cryst. 31, 733–741.Google Scholar
Arndt, U. W., Long, J. V. P. & Duncumb, P. (1998). A microfocus X-ray tube used with focusing collimators. J. Appl. Cryst. 31, 936–944.Google Scholar








































to end of page
to top of page