INSITU X-RAY-DIFFRACTION OF DIACETYLENE MONOLAYERS

The in situ surface crystalline parameters of two diacetylene, 12-8 and 16-8 monolayers on a LiOH/H2O substrate, were measured by glancing incidence synchrotron X-ray diffraction. The monolayers were formed in an ultra-clean quartz trough by the addition method and further compressed by a pivot barrier. Diffraction scans were measured on non-polymerized and pre-polymerized monolayers. Surface pressure was monitored by Whilhelmy plate, which was then removed before polymerization and exposure to the X-ray beam. The monolayers were illuminated by low-angle (0.098-degrees off of the surface plane) incident X-rays (7600eV, 1.63 angstrom) from the NRL Materials Research Line, X-23B, at NSLS, Brookhaven National Laboratory.