Powder Handling Device for Analytical Instruments

This invention is a system and associated method for causing a fine-grained powder in a sample holder to undergo at least one of three motions (vibration, rotation or translation) at a selected motion frequency in order to expose a statistically relevant population of grains in random orientation to a diffraction or fluorescent source. One or more measurements of diffraction, fluorescence, spectroscopic interaction, transmission, absorption and/or reflection can be made on the sample, using x-rays or light in a selected wavelength region. In one embodiment, the invention allows the relaxation of sample preparation and handling requirements for powder X-ray Diffraction (pXRD). The sample, held between two thin plastic windows, undergoes granular convection similar to a heated liquid, causing the individual grains to move past a collimated X-ray beam in random orientation over time. The result is an X-ray diffraction pattern having the correct diffracted intensities without a requirement for specialized mechanical motions. A major improvement over conventional sample preparation and handling techniques for pXRD is the potential to characterize larger grain-size material, resulting in a significant relaxation of the constraints on sample preparation (grinding). The powder handling system as described extends the range of useful grain sizes for XRD/ X-ray fluorescence (XRF) from a few micrometers (m) to several hundred m. Inclusion of the powder handling system enables automated instruments such as CheMin, a robotic XRD/XRF instrument designed and developed by NASA, to analyze as-received or coarsely powdered samples on NASAs Mars Science Laboratory rover, or in extreme, toxic or hazardous environments on Earth.