Analysis of High Pressure Area Detector Data: From Powders to Single Crystals (and vice versa). A P Hammersley^*, D Haeusermann^*, M Kunz^*, R Angel⁺, and L Finger⁺; ^*ESRF, BP 220, Grenoble 38043, France, ⁺Universitaet Bayreuth, D-95440 Bayreuth, Germany

Area detectors together with versatile analysis techniques could lead to new advances in single crystal High Pressure research, analogous to powder diffraction are detector work.

FIT2D is an analysis program which allows the integration of Debye-Scherrer rings to "2-theta scans" whilst allowing contaminating single crystal reflections e.g. diamond reflections to be avoided [1]. Such work has allowed important advances in High Pressure research, despite lower resolution than conventional diffractometers and the problem of increased background. This technique has found a number of applications in other areas of powder diffraction e.g. micro samples.

By reversing the process we can calculate and subtract the Debye-Scherrer rings leaving only Bragg reflections. Rings from the sample cell can be separated from reflections, and indexing and integration performed. This technique is unlikely to compete with conventional diffractometers for simple samples, but can offer much faster data collection and thus the possibility of time-resolved information, and can cope with more difficult problems such as mixed phases and multi-crystals.

The techniques are under development and the latest results will be shown.

[1] Hammersley A P, Svensson S O, Hanfland M, Fitch A N,

Haeusermann D (1996). High Pressure Research, 14, 235-248.