High resolution electron energy loss spectroscopy of fatty acids prepared by langmuir-blodgett techniques on polycrystalline silver

The surface of monomolecular layers of fatty acids prepared by Langmuir-Blodgett methods on polycrystalline silver has been studied by High Resolution Electron Energy Loss Spectroscopy (HREELS). Results demonstrate HREELS sensitivity to large molecules in molecular organizates on polycrystalline substrates. Spectra are interpreted in comparison with infrared vibrational data; results allow differentiation of degrees of unsaturation. The carbonyl vibration loss is observed as a weak feature, explained as due to the orientation of the fatty acid heads "down" on the subtrate surface approximately 20 Å from the scattering interaction.