VACUUM STABILITY OF LANGMUIR-BLODGETT-FILMS OF FATTY-ACIDS AND FATTY-ACID SALTS

The vacuum stability of Langmuir-Blodgett films consisting of fatty ac ids and Cd salts of fatty acids deposited on various substrates was in vestigated by means of plasma desorption mass spectrometry. Plain fatt y acid films (particularly thin ones) exhibit a remarkable instability . Exceptions occur when the films are deposited on metal substrates co vered with the natural oxide. In this case cation exchange occurs whic h results in the formation of salt (or a mixture of salt and acid) fil ms exhibiting reasonable stability. Thin films consisting of 100% salt are fairly stable in vacuum.