X-ray-scattering information obtained from near-field speckle

Whenever coherent radiation impinges on a scattering object, a speckled intensity pattern is produced. In the far field the speckle size and shape do not mirror any properties of the object. Here we show that, in spite of the limited spatial coherence of synchrotron radiation, speckles with remarkable properties can be observed when the sensor is placed in the near field. The statistical analysis of these speckles generates static and dynamic X-ray-scattering data, and the results from two typical scattering samples are given. When compared with conventional far-field techniques, the method enables a substantial increase of around four orders of magnitude in the beam size and power and opens the way to a previously inaccessible region of scattering angles. It also offers the possibility of tracking the spatio-temporal evolution of complex fluids and other inhomogeneous systems.