Application of Micro- and Nanobeams for Materials Science

Abstract

Owing to the spatial resolution and sensitivity (i.e., signal-to-background ratio), nano-and micro-X-ray beams are emerging tools with a strong impact in materials science. Although the optical quality of the X-ray focusing devices has limited the progress of X-ray microscopy, recent advances in fabrication techniques as well as in theoretical approaches have pushed the spatial resolution toward the diffraction limit. As a result, materials research using nano-and micro-X-ray beams has begun to extend toward the atomic domain, with concomitant and continuous developments of multiple analytical tools. The study of micro-/nanoscale objects, small embedded domains with weak signals, and/or heterogeneous structures at the (sub)micrometer scales has required the use of intense X-ray pencil beams. Additionally, stimulated by the great brilliance with reduced emittance of current third-generation synchrotron sources and new developments in X-ray detector technology, today intense (sub)micron X-ray beams are available with a variety of focusing devices. Finally, thanks to the multiple interactions of X-rays with matter, these X-ray probes can be used for manifold purposes, such as ultrasensitive elemental/chemical detection using X-ray fluorescence/X-ray absorption, or for identification of minority phases and/or strain fields by Xray diffraction with (sub)micron resolution. Here we describe how (sub)micrometer X-ray beams are produced and used today using refractive, reflective, and diffractive X-ray optics. We show that micro-and nano-X-ray beams are key tools for space-resolved determination of structural and electronic properties and for chemical speciation of nanostructured or composite materials. Selected recent examples will range from phase separation in single nanowires to visualization of dislocations and buried interfacial defects to domain distortions and quantum confinement effects. Keywords