Coherent X-ray Diffraction at NSLS-II

March 14, 2008

The purpose of this workshop is to develop the scientific and technical case for a beamline for coherent imaging experiments at NSLS-II that will be used to image crystalline matter on the nanoscale, single molecules and small clusters by Coherent X-ray Diffraction (CXD) and to image extended samples by X-ray ptychography. The Beamline Advisory Team (BAT) will be formed and will use the results of the workshop discussions to submit a Letter of Interest (LOI) to develop the beamline with NSLS-II.

One of the original justifications for building NSLS-II was to enable the science of Coherent X-ray Diffraction (CXD), which depends so strongly on the brightness of a synchrotron radiation source. There is a reasonable expectation that the technique will be able to reach atomic resolution with the current design parameters of NSLS-II, which provide almost two order more coherent flux than existing sources. In its 'single molecule' or cluster mode, the method uses a large area detector to capture the forward scattering from an individual sample for which many identical copies are available. These might be lined up on a support, aligned in a magnet or an optical trap or simply sprayed through the beam. Powerful new methods of 'classifying' the orientations of individual diffraction frames to compose a full three dimensional data set are under development and will be presented at the workshop. Classical CXD of crystalline grains will be developed further to take advantage of i) the significantly improved brightness of NSLS-II ii) the improved sample positioning technology that has emerged from the semiconductor industry iii) the improved algorithms for inverting the diffraction data to images. These advances, as well as the questions surrounding the interpretation of complex 3D images (by inversion of asymmetric diffraction patterns) will be presented at the workshop.

X-ray ptychography has recently emerged as a future extension of CXD for lensless imaging of extended samples. It has the potential of wide application to the same kinds of samples currently studied by electron microscopy, but with the unique advantages of X-rays. We expect to have workshop presentations on the method and a discussion of the instrumentation requirements needed for it to flourish at NSLS-II.

It is expected that the participants will discuss future applications of CXD methodology and discuss examples of materials systems that can be studied with the techniques, including nanoscale semiconductor devices, domain formation in ferroelectrics, magnetic domain formation, materials at high pressure and catalyst particles. Ideas for the sample environments that would be needed for the beamline to serve the user community will be discussed.

Agenda

Last Modified: April 11, 2008
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