Lawrence Bragg, microdiffraction and X-ray lasers

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4 Scopus citations

Abstract

We trace the historical development of W. L. Braggs law and the key experimental observation which made it possible using polychromatic radiation at a time when neither X-ray wavelengths nor cell constants were known. This led, through his phasing and solving large mineral structures (without use of a computer), to work on metals, proteins, bubble rafts and his X-ray microscope. The relationship of this to early X-ray microdiffraction is outlined, followed by a brief review of electron microdiffraction methods, where electron-probe sizes smaller than one unit cell can be formed with an interesting failure of Braggs law. We end with a review of recent femtosecond X-ray snapshot diffraction from protein nanocrystals, using an X-ray laser which generates pulses so short that they terminate before radiation damage can commence, yet subsequently destroy the sample. In this way, using short pulses instead of freezing, the nexus between dose, resolution and crystal size has been broken, opening the way to time-resolved diffraction without damage for a stream of identical particles.

Original languageEnglish (US)
Pages (from-to)25-33
Number of pages9
JournalActa Crystallographica Section A: Foundations of Crystallography
Volume69
Issue number1
DOIs
StatePublished - Jan 1 2013

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Keywords

  • Braggs law
  • CBED
  • X-ray lasers
  • convergent-beam electron diffraction
  • microdiffraction
  • time-resolved diffraction

ASJC Scopus subject areas

  • Structural Biology

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