Non destructive nanoscale characterization with x-ray: the case of SAXS/WAXS

P. Panine
Xenocs, FR

Keywords: nanoscale, characterization, x-ray, SAXS/WAXS

Summary:

Characterization at the nanoscale in soft materials is usually difficult, sample preparation in conventional microscopy being often considered as a blocking point. Characterization of buried nanostructure in a solid matrix is also often difficult without sample destruction, slicing techniques etc... In these cases, x-ray techniques have a major asset due to the high penetration power in matter, enabling investigation of bulk material, without preparation, even on high-z containing materials, both in liquid or solid state or even in the gas state. Moreover, the information has usually a high statistical quality, since data arise from a large volume average, in contradiction to local probe usually encountered in classical microscopy. This technique is known as small angle scattering and is usually coupled to wide angle x-ray scattering. This combination offers to covers over a broad range of characteristic dimensions, from 1.5 Å up to 10000 Å. The quality of a small angle scattering setup, the experimental time and the ultimate performances expected at low values of q-wave vector are strongly related to the flux density on the sample. Further, the propagation of the beam used for the experiment towards the detector is driving the performances of the instrument. In the synchrotron beamlines, the time resolution and the finest beam size are the main asset of existing setup. Laboratory setups are recently emerging again with reasonable experimental times and two strategies are coexisting, the first one is to use a convergent beam focused on the detector and the second is based on a parallel beam and long sample-to-detector distances. In the convergent case, the flux level is privileged while in the parallel beam configuration, lowest values of wave vector are sought. The aim of this paper is to rapidly introduce the SAXS technique and to cover both synchrotron and laboratory setups, and to present the recent progress in the hardware. More specially, progress in the field of single reflexion multilayer optics [1] and collimation devices [2] will be emphasized.