INVESTIGATION OF STEARIC-ACID AND MANGANESE STEARATE FILMS OBTAINED BY LANGMUIR-BLODGETT AND VACUUM DEPOSITION METHODS

The molecular structure and morphology of 1-100 nm films, prepared by vacuum deposition of stearic acid (HSt) and manganese stearate (MnSt(2 )) on Si, NaCl and C/NaCl substrates, have been investigated by Fourie r transform IR spectroscopy, scanning electron microscopy and transmis sion electron diffraction techniques and compared with characteristics of Langmuir-Blodgett films on Si. Contrary to previous work, more emp hasis is placed on films a few nanometres thick. The parameters (frequ encies and intensities) of the Davydov splitting components in IR spec tra are evaluated to determine the molecular orientation and intermole cular interaction in these films. HSt shows a three-dimensional growth in vacuum-deposited films on all substrates studied which is evidence of a weak interaction of H-bonded HSt dimers and the substrate. MnSt, is found to decompose upon evaporation, resulting in stearone (C17H35 )(2)CO formation and deposition. The orientation of these molecules de pends on the substrate type. A Stranski-Krastanov growth mechanism is realized owing to the strong interaction of polar stearone molecules w ith the substrates. The possible reasons for the distinction of the HS t and the stearone interactions with the substrates are discussed. The Langmuir-Blodgett films exhibit a higher thickness uniformity but low er molecular ordering than vacuum-deposited films do.