DEDXS - THE DIFFERENTIAL ENERGY-DISPERSIVE X-RAY SPECTROSCOPY SYSTEM AND ITS USE IN ELECTRIC-FIELD MODULATION STUDIES

The original implementation of a differential energy-dispersive X-ray spectroscopy system and its application to electric field studies suff ered from certain limitations. These have been overcome in a new desig n featuring four high-voltage photo-transistor switches with very fast rise times arranged in a bridge configuration. The enhanced system ha s a 4-step duty cycle, can handle up to 5 kV and can be switched over a six-decade range of frequency, from 1 mHz to 1 kHz. Examples from a study of the effect of electric field on the structure of LiNbO3 are u sed to illustrate experimental protocols. Investigations over periods of several days brought to light an unusual drift in the solid-state d etection system. Correction of this drift by intrinsic calibration rev ealed the remarkable precision of the new system, O(10(-5)), and showe d that X-ray refraction effects in Bragg reflection, O(5 x 10(-5)), ca n be resolved easily.