ANNEALING EFFECTS ON MOLECULAR-ORIENTATION IN EVAPORATED-FILMS OF N-PARAFFINS

The time variation in the X-ray intensities of the 006 and 110 reflections from n-C33 H68 films evaporated on glass substrates was investigated in order to elucidate the mechanism of reorientation of molecular chains during the annealing process. The experimental results revealed that the number of molecules oriented normally to the substrate increases with annealing time, while the number with lateral orientation decreases at a different rate. Further data analysis suggested that this molecular reorientation proceeds via groups consisting of about four molecules when they acquire simultaneously a thermal energy comparable to that of fusion.