Applications of laboratory-based X-ray microbeam diffraction and fluorescence analysis

Abstract

The quantitative structural and chemical analysis of bulk materials is generally done using x-ray diffraction and fluorescence techniques. This is due, in large part, to the vast body of work which has gone into characterizing the x-ray scattering process and the ease with which this interaction canbe kinematically modeled to high precision. Other salient features of x-ray analytical techniques aretheir use as subsurface probes, they require minimal specimen preparation, and ambient conditions are generally adequate for analysis. However, as microanalytical tools, these techniques were typically abandoned because of the difficulty encountered in confining the x-rays to dimensions <<.1 mm with sufficient intensity for a timely analysis. Recently, there has been a rekindled interestin x-ray microbeam analysis because of the reintroduction of tapered capillaries as total reflection x-ray optics. Tapered capillaries can essentially capture larger solid angles nearer the x-ray sourceand act as x-ray wave guides to transport the x-rays to the specimen with high efficiency. It is now possible using laboratory x-ray sources, to produce x-ray beams suitable for diffraction or fluorescence analysis, with diameters in the range of 3-12 μm. X-ray diffraction patterns have been acquired from diffraction volumes as small as 2 μm and fluorescence maps with 5 μm spatialresolution have been demonstrated.