Adaptation of a linear diffractometer to measure three X-ray reflections quasi-simultaneously

Abstract

A single-crystal linear diffractometer has been adapted to measure three reflections quasi-simultaneously in the flat-cone setting. Three counters are mounted in echelon, with their windows vertically above each other, at the end of a draw tube whose length may be so adjusted that x-rays from reflections in three adjacent reciprocal lattice levels are recorded in the course of a single measurement cycle. The outputs from the detectors are fed into three parallel amplifying and counting chains and the results are recorded sequentially on punched paper tape by means of a printing-out programmed scaler. Modifications to the diffractometer control system permit the blind region of the flat-cone setting to be avoided automatically. The data-processing computer programme has been amended to take account of the new system of measurement. Practical experience with the diffractometer is described. The increased rate of data collection is particularly valuable when crystals are liable to irradiation damage.