Capilliaries are predominantly used either for very small sample amounts, when the sample has to be air-tightly sealed, or when the sample requires accessory heating or tempering.
As capillaries only cover approximately 10% of the X-ray cross section, the intensity of the refraction lines is one order of magnitude smaller than that of flat samples. In addition, the refraction lines increase in width due to the greater sample thickness of the capillaries from 0.2mm to 0.5mm. Despite this it is still possible to record spectra of high quality due to the optimised geometry of the G670 and its high-resolution detection method.
At first the capillaries are mounted in a brass tube which is in turn mounted on a small adjustable goniometer head. After this, a microscope is used to gyrationally centre the sample and then mounted on the sample holder. This contains a small direct current motor which rotates the capillaries at approx. 60 revs/min.