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Title: Soft x Rays from a Free-electron Laser Resolve a Single, Micron-sized Structure

Abstract

If photons are to map an object's structure, their wavelength must be no bigger than the object's finest features. But the shorter the wavelength, the greater the destructive energy each photon packs. Structural biologists get away with using x rays to map proteins and other biomolecules, but only because countless identical copies of a molecule, when arrayed in a crystal, share the radiation dose.

Authors:
Publication Date:
OSTI Identifier:
20849481
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics Today; Journal Volume: 60; Journal Issue: 1; Other Information: DOI: 10.1063/1.2709544; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CRYSTALS; FREE ELECTRON LASERS; MOLECULES; PHOTONS; PROTEINS; RADIATION DOSES; SOFT X RADIATION; WAVELENGTHS

Citation Formats

Day, Charles. Soft x Rays from a Free-electron Laser Resolve a Single, Micron-sized Structure. United States: N. p., 2007. Web. doi:10.1063/1.2709544.
Day, Charles. Soft x Rays from a Free-electron Laser Resolve a Single, Micron-sized Structure. United States. doi:10.1063/1.2709544.
Day, Charles. Mon . "Soft x Rays from a Free-electron Laser Resolve a Single, Micron-sized Structure". United States. doi:10.1063/1.2709544.
@article{osti_20849481,
title = {Soft x Rays from a Free-electron Laser Resolve a Single, Micron-sized Structure},
author = {Day, Charles},
abstractNote = {If photons are to map an object's structure, their wavelength must be no bigger than the object's finest features. But the shorter the wavelength, the greater the destructive energy each photon packs. Structural biologists get away with using x rays to map proteins and other biomolecules, but only because countless identical copies of a molecule, when arrayed in a crystal, share the radiation dose.},
doi = {10.1063/1.2709544},
journal = {Physics Today},
number = 1,
volume = 60,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
}
  • X-ray crystallography is remarkably successful at yielding atomic-resolution structures of proteins and other biological molecules. But that success has relied on growing macroscopic crystals. The countless identical molecules arrayed in a crystal share a radiation dose orders of magnitude higher than any one of them could tolerate alone. Moreover, the interference of x rays elastically scattered from the molecules concentrates the scattering intensity in a set of Bragg peaks. The larger the crystal, the better the signal-to-noise ratio.
  • We have demonstrated diffraction from Si(111) crystal using x rays from highly ionized Ar ions produced by laser irradiation with an intensity of 6x10{sup 18}W/cm{sup 2} and a pulse duration of 30 fs acting upon micron-sized Ar clusters. The measured total photon flux and linewidth in the He{sub {alpha}}{sub 1} line (3.14 keV) were 4x10{sup 7}photons/shot/4{pi}sr and 3.7 eV (full width at half maximum), respectively, which is sufficient to utilize as a debris-free light source for time-resolved x-ray diffraction studies.
  • Coherent harmonic generation using single-pass free-electron lasers is a promising method for generating coherent radiation in the vacuum ultraviolet and x-ray spectral region. We propose a simple scheme allowing one to generate powerful coherent radiation in the soft x-ray region by making use of present available technology. The method relies on the possibility of creating substantial bunching in a relativistic electron beam, while limiting the growth of its energy spread. The validity of the scheme is demonstrated using a simple one-dimensional model. Results are confirmed by three-dimensional simulations.
  • We report on single-pulse resonant magnetic scattering experiments using soft x-ray pulses generated by the free-electron laser FLASH at DESY. We could record a magnetic diffraction pattern from a Co/Pt multilayer sample at the Co M{sub 2,3} edge with a single 30-fs-long FEL pulse. The analysis of the magnetic small-angle scattering signal for subsequent pulses indicates a threshold energy density below which there is no indication that the magnetic properties of the sample might be altered.
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