Intensity measurement with a fixed specimen in a neutron single-crystal diffractometer

In neutron single-crystal diffractometry integrated intensities are usually measured by rotating the specimen through the reflecting position. It is possible, however, to produce a monochromatic beam with properties that allow intensity measurement with a fixed specimen. For this bent monochromators are especially suitable, but plane mosaic-crystal monochromators in antiparallel (+) position can also be used. The production, suitability and use of a plastically bent germanium monochromator is discussed. By means of a structure determination of the room-temperature phase of NH4Br, intensity measurements with a fixed specimen are compared with measurements of integrated intensities. With regard to accuracy, the methods are equivalent. With a bent germanium monochromator, the intensity measurement with a fixed specimen leads, especially in the range of high Bragg angles, to a reduction of the measuring time by a factor of at least two.