A New Method for Fast XRPD Using a Position Sensitive Detector

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Abstract
The scanning speed of powder diffractometers can be increased by about two orders of magnitude by replacing the normal detection system (receiving slit/scintillation counter) by a linear position sensitive detector (PSD) which collects diffracted x-rays of a larger part of the diffractometer measuring arc simultaneously. The velocity increase is proportional to the section of the arc 29 in which the diffracted x-rays are detected. With respect to the Bragg-Brentano focussing geometry, a range of several degrees (typically 5°) can be tolerated without affecting the resolution remarkably. Diffractograms over extended angular regions of 2θ are received by slewing the PSD continuously along the arc while the diffracted x-rays are accumulated with their accurate 2θ angle address on a digital base. The method has been named the continuous position sensitive detection technique (CPSD). With this technique, diffraction patterns with similar quality (resolution, linearity, peak/background ratio) as conventional, scintillation counter recorded diagrams can be received at slewing rates of several hundred degrees per minute. Additionally, the CPSD technique augments the number of crystallites contributing to the diffraction intensity by the same amount, thus producing much better crystallite statistics for quantitative measurements.

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