X-ray diffraction of pentacosdiyne-8,10 acid-1 Langmuir-Blodgett film

Abstract

Pentacosdiyne-8,10 acid-1 (PCDA) was synthesized and deposited by the Langmuir-Blodgett (LB) technique on to glass, quartz and gold-covered glass slides. X-ray diffraction at low angle has been used to investigate the periodic structure of the LB film and the effect of polymerization on the structure. Up to seven Bragg diffraction peaks were observed in the 2θ angle range from 1‡ to 15‡. From these, the spacings of molecules in the LB film and the angle of molecular orientation on the substrate were calculated, A molecular arrangement model was employed to calculate the intensities of diffraction peaks. The calculated result was in qualitative agreement with the experimental phenomenon of the “even-odd intensity oscillation”.