A microprocessor-controlled continuous-flow cryostat for single-crystal X-ray diffraction in the range 10-300 K

A low-temperature attachment for Weissenberg cameras operating in the range 10-300 K is described. It consists of an Oxford Instruments continuous-flow helium cryostat and a laboratory-built microprocessor-based temperature controller. The temperature stability and accuracy of the controller are both to better than ±0.1 K over the entire range of operation. Helium consumption is 0.2 l h^-1 at 200 K, 0.3 l h^-1 at 100 K, 0.65 l h^-1 at 30 K and 1.5 l h^-1 at 10 K. Slight modifications to the Weissenberg camera enable it to be operated in a continuous-recording mode, in which a series of oscillation photographs may be taken at different temperatures. The very sophisticated temperature programming system allows complex experiments of this type to be carried out automatically, requiring no intervention by the operator.