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Title: Lawrence Bragg, microdiffraction and X-ray lasers

Abstract

We trace the historical development of W. L. Bragg's `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 Bragg's 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. 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.

Authors:
 [1]
  1. Arizona State Univ., Tempe, AZ (United States)
Publication Date:
Research Org.:
Arizona State Univ., Tempe, AZ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1158815
Report Number(s):
DOE-ASU-45996
Journal ID: ISSN 0108-7673
DOE Contract Number:  
FG03-02ER45996
Resource Type:
Journal Article
Journal Name:
Acta Crystallographica. Section A, Foundations of Crystallography
Additional Journal Information:
Journal Volume: 69; Journal Issue: 6; Journal ID: ISSN 0108-7673
Publisher:
International Union of Crystallography
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Bragg's law; microdiffraction; convergent-beam electron diffraction; CBED; X-ray lasers; time-resolved diffraction

Citation Formats

Spence, John. Lawrence Bragg, microdiffraction and X-ray lasers. United States: N. p., 2012. Web. doi:10.1107/S0108767312046296.
Spence, John. Lawrence Bragg, microdiffraction and X-ray lasers. United States. doi:10.1107/S0108767312046296.
Spence, John. Thu . "Lawrence Bragg, microdiffraction and X-ray lasers". United States. doi:10.1107/S0108767312046296.
@article{osti_1158815,
title = {Lawrence Bragg, microdiffraction and X-ray lasers},
author = {Spence, John},
abstractNote = {We trace the historical development of W. L. Bragg's `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 Bragg's 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. 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.},
doi = {10.1107/S0108767312046296},
journal = {Acta Crystallographica. Section A, Foundations of Crystallography},
issn = {0108-7673},
number = 6,
volume = 69,
place = {United States},
year = {2012},
month = {11}
}