QUANTITATIVE ASPECTS OF SECONDARY ION MASS-SPECTROMETRY ANALYSIS OF PURE AND MIXED FATTY-ACID LANGMUIR-BLODGETT-FILMS

Polycrystalline silver supported pure and mixed mono- and multilayer films of eicosanoic [CH3(CH2)18COOH] and docosanoic [CH3(CH2)20COOH] acids have been prepared by the standard Langmuir-Blodgett technique. The emission of quasimoiecular ions as a function of ion dosage has been studied to infer information regarding secondary ion stability under ion bombardment. The results indicate molecular orientation and substrate dependence for (M + H)+ emission and the attenuation of (M + Ag)+ and (M — H + 2Ag)+ with increased film thickness. Data are presented for studies conducted on both quadrupole mass filter and time-of-flight instrumentation. The effects of supporting substrate morphology, instrumentation, and implications for quantification of molecular static-secondary ion mass spectrometry (static-SIMS) ion emission are discussed. © 1990, American Vacuum Society. All rights reserved.