X-ray wave guiding using three-beam Bragg-surface diffraction

A diffraction-type of X-ray wave guide, in contrast to refraction-type, is proposed using three-beam diffraction geometry to generate a surface diffracted beam propagating along the direction of the wave guide. The three-beam Bragg-Surface diffraction involves a symmetric Bragg reflection and a surface diffraction. The former is used to guide a wide-angle incident beam into a silicon crystal. The simultaneously occurring surface diffraction then guides the diffracted beam propagating along the direction of the wave guide that is parallel to the crystal surface. A wave guide with a shallow ditch is then manufactured along the direction of the surface diffraction using the conventional lithographic technique. As a whole the wave guide consists of a three-layer structure of tantalum/photon resist (PMMA)/tantalum, on the Silicon substrate. The surface diffracted X-rays can then be confined in and guided along the layer of photon resist. Details of the design of the wave guide and synchrotron diffraction experiments will be reported.