Measurement of femtometre-scale atomic displacements by X-ray absorption spectroscopy

• Published in: Nature 2005-05, Vol.435 (7038), p.78-81
• Main Authors: Pettifer, Robert F, Mathon, Olivier, Pascarelli, Sakura, Cooke, Michael D, Gibbs, Michael R. J
• Format: Article
• Language: English
• Subjects: Absorption spectroscopy; Atoms & subatomic particles; Cobalt; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Humanities and Social Sciences; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; letter; Measurements common to several branches of physics and astronomy; Metrology, measurements and laboratory procedures; multidisciplinary; Physics; Scattering; Science; Science (multidisciplinary); Spatial dimensions (e.g.: position, lengths, volume, angles, displacements, including nanometer-scale displacements); Spatial dimensions (eg, position, lengths, volume, angles, displacements, including nanometer-scale displacements); Spectrum analysis; Structure of solids and liquids; crystallography; Thin films; X- and γ-ray instruments and techniques; X- and γ-ray spectrometers; X-ray absorption spectroscopy: exafs, nexafs, xanes, etc; X-ray and γ-ray spectrometers; X-ray diffraction and scattering; X-rays
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature03516

The frequencies of extended X-ray absorption fine-structure (EXAFS) measurements, which are oscillations occurring on the high-energy side of an X-ray absorption edge, can be used to identify interatomic distances in materials. We have used a dispersive X-ray spectrometer, which has no moving components, to make rapid measurements with minimal energy drift of the difference in EXAFS from the Fe K edge in an iron-cobalt thin film undergoing periodic strain through magnetostriction. We show that magnetostriction can be detected by differential X-ray absorption. The magnitude of the recorded signal relative to the noise shows a sensitivity to mean differential atomic motion of one femtometre: a factor of 100 times more sensitive than that normally available.