On the use of a four-circle X-ray diffractometer

Three methods of using a four-circle x-ray diffractometer are described. According to method No 1 the crystal is orientated with one given crystallographic axis parallel to the phi axis of the instrument and a reciprocal axis normal to the first axis is set perpendicular to the χ and phi axes. The cell dimensions must be accurately known. According to method No 2 the crystal is set up with an arbitrary unknown orientation which is found by measurement on the diffractometer. The cell dimensions must be known as in method No 1. According to method No 3 the crystal is set up with an arbitrary unknown orientation and the cell dimensions need not be known at all. Both the orientation and the cell dimensions are found in the course of the work.