Scientists at the Paul Scherrer Institute and ETH Zurich (Switzerland) have created 3D images of tiny objects showing details down to 25 nanometres (1 nanometre = 1 millionth of a millimetre). In addition to the shape, the scientists determined how particular chemical elements were distributed in their sample and whether these elements were in a chemical compound or in their pure state.
The measurements were performed at the Swiss Light Source at the Paul Scherrer Institute using a method called phase tomography. As in other types of tomography, here x-rays are shone through the sample from different directions to give images from many perspectives. These images are combined using a computer program to give a 3D image.
The method was demonstrated using a football-like structure called a “buckyball”, only 6 thousandths of a millimetre across, which was fabricated with the latest 3D laser technology. In addition to showing the shape of the object, the method allowed the scientists to pinpoint the locations of a specific chemical element (Cobalt) and deduce further information on the environment of its atoms. They made use of the fact that different elements interact differently with light of different energies, like different colours in visible light, allowing them to see the distribution of a specific element within the sample.
Being able to distinguish different elements and their compounds on the nanometre scale in three dimensions is highly relevant in the development of novel electronic and magnetic parts or more efficient catalysts for the chemical industry.
Element-Specific X-Ray Phase Tomography of 3D Structures at the Nanoscale
Claire Donnelly, Manuel Guizar-Sicairos, Valerio Scagnoli, Mirko Holler, Thomas Huthwelker,
Andreas Menzel, Ismo Vartiainen, Elisabeth Müller, Eugenie Kirk, Sebastian Gliga, Jörg Raabe, and Laura J. Heyderman.,
Phys. Rev. Lett. 114, 115501 (2015);
DOI: 10.1103/PhysRevLett.114.115501 ; Published: 20 March 2015
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 : http://www.psi.ch/media/matter-and-material
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 : http://dx.doi.org/10.1103/PhysRevLett.114.115501
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