TIME-RESOLVED GRAZING-INCIDENCE DIFFRACTION STUDIES OF THIN-FILMS USING AN IMAGING-PLATE CAMERA AND FOCUSING MONOCHROMATOR

A multiple imaging-plate (IP) detector system and focusing monochromat or have been developed and successfully applied to the time-resolved s tudy of phase transitions in Langmuir-Blodgett (LB) films by grazing-i ncidence X-ray diffraction (GIXD). The first reported application of i maging plates to a GIXD study was carried out by our group and proved to be very successful in the determination of thin-film structure [For an, Peng, Steitz, Barnes & Gentle (1996). Langmuir, 12, 774-777]. To e xtend the capabilities of this system, an IP camera was designed and b uilt which can accommodate up to 13 IPs (40 x 20 cm) inside the vacuum chamber of the main diffractometer at the Australian Beamline at the Photon Factory. The camera allows the enclosed IPs to be successively exposed and stored inside the diffractometer for later scanning. The f ocusing monochromator employed in this technique combines fixed exit-b eam height with sagittal focusing of the second crystal and delivers a gain in flux of >20 times when measured through a 0.1 x 0.1 mm apertu re. The utility of the system incorporating the IP camera and the focu sing monochromator has been demonstrated through the study of temperat ure-dependent phase transitions in LB films of metal fatty acids.