ON THE POLYMORPHISM AND GROWTH OF STEARIC-ACID THIN-FILMS PREPARED BY VACUUM-DEPOSITION

Stearic acid (SA) vacuum-deposited on mica and on sodium chloride grew as the C polymorph of SA. Both B and C forms of SA grew on a substrate in the B form of SA. Calculations of molecular interactions of an SA crystal on the (001) NaCl and the (001) B form of SA substrates have been carried out to interpret the phenomena. Three dimers of both B and C forms are the size of the critical nucleus on the NaCl substrates. No epitaxial relation was found on these substrates. The ratio of the nucleation rates of the B and C forms was 1.4 x 10-9, and the B form never grew on the NaCl substrates. Some epitaxial relations in respect of the SA-B form substrate was found for both forms, which could grow on B form substrates. The critical nuclei has nine dimers in dimorphs. © 1990, Elsevier Science Publishers B.V.. All rights reserved.