POWDER DIFFRACTION IN THE RANGE OF MILLISECONDS

Powder diffraction studies with synchrotron radiation were performed on a time scale down to 2.5 ms at the HASYLAB beamline B2 with a commercial 1024 pixel linear photodiode-array detector system (OMA III, EG&G-PARC). The flux rate of 2 x 10(8) photons s-1 at a wavelength of 1.26 angstrom achieved by using a toroidal mirror and a standard double-crystal Si(111) monochromator was measured with an ionization chamber at the focus. With a synthetic multilayer to select the desired wavelength instead of the standard monochromator, a flux rate of 1.5 x 10(10) photons s-1 was measured at a wavelength of 1.31 angstrom. The shortest possible recording times for a complete powder pattern of calcium fluoride were 200 ms with the crystal monochromator and 2.5 ms with the multilayer. The angular resolution for both cases is discussed. The high-speed data collection was successfully applied with the double-crystal and multilayer monochromators to the recording of more-complex patterns and to monitor a phase transformation in order to demonstrate the feasibility of kinetic studies on the millisecond time scale.