Research team led by DESY and MAX IV scientists adapts important X-ray analysis method for use with difficult-to-move samples
Sometimes a change of perspective can make a world of difference. A team of scientists from DESY and MAX IV as well as University of Bayreuth has rearranged the method in which one can use an X-ray beam to image a sample without using high-quality lenses. The method, called ptychography, has been widely used at synchrotrons and free-electron lasers to analyse the inner workings of materials quickly enough while avoiding major damage to the sample by the X-rays. The team has turned the standard method of ptychography on its head: Instead of moving the sample around the X-ray beam, they have figured out how to move the X-ray beam itself in a way that does not alter the properties of the X-rays while still accomplishing the effect of ptychographic analysis. Moreover, they have tested the method on a sample that is in and of itself difficult to move – short-lived states of matter under extreme conditions of pressure and temperature. The team has published their findings in the Proceedings of the U.S. National Academy of Sciences (PNAS).
X-ray ptychography has become, in recent years, a standard technique in the toolbox of researchers using X-ray light sources. In a wide variety of fields, including biology and geology, the technique has been critical for imaging the interiors of samples up to atomic-scale detail non-destructively, revealing details on a scale that methods of light and electron microscopy cannot reach. Up to now, ptychography has been accomplished by using extremely precise sample movers that would change the position of the sample relative to the X-ray beam by tiny lengths – sometimes to the nanometre level – creating a grid pattern of sequentially imaged spots that eventually revealed the full image. Called high-resolution phase-contrast imaging, it has provided insights into the nanoscale structures of tiny biological structures, mineral deposits, computer chips and much more.
Read more on the DESY website
Image: Two views of an extreme-states experiment: To the left is an X-ray micrograph of the sample set up, which consisted of a piece of elemental iron surrounded by solid oxygen, itself surrounded by a rhenium gasket within a diamond anvil cell creating intense pressure. To the right is a ptychographic reconstruction of the area of the sample hit by X-rays, shown with a green circle. In that area using their new ptychographic method, the team could reconstruct the oxidation of the iron being melted by the intense pressure. An extreme-states experiment of this kind has not before been imaged in this way.
Credit: Tang Li, DESY
