Back-reflection energy-dispersive X-ray diffraction: a novel diffraction technique with almost complete insensitivity to sample morphology

A novel X-ray diffraction (XRD) technique, which exhibits almost complete insensitivity to the morphology of and distance to the sample, is presented for the first time. This technique applies energy-dispersive XRD (EDXRD) in a back-reflection geometry, with 2θ ≃ 180°. Although this geometry leads to low resolution of diffraction peaks and the greatest overlap with fluorescence peaks, it nevertheless yields a combination of properties that are unique in the field of X-ray diffractometry. It is likely that diffraction patterns can be obtained with no or very minimal sample preparation. Furthermore, the intrinsic geometry of the method and the simplicity inherent to EDXRD enables a compact lightweight instrument design, suitable for field-portable or hand-held XRD and X-ray fluorescence analysis. Application to geological and planetary science is emphasized in this paper. The characteristics of the technique are elucidated via theoretical considerations and ray-trace modelling, and the simplest possible implementation is described.