Spectra of polystyrene film surfaces achieving a resolution of 2.55 meV (20.4 cm−1) were recorded using new generation high resolution electron energy loss spectroscopy spectrometers. Spectra show a high number of characteristic energy losses corresponding to infrared- and Raman-active modes. Mechanisms involved in the electron interaction with the film surface were unraveled through their energy dependence. Impact is the predominant mechanism revealing an analysis depth of some angstroms. Absence of dipole mechanisms is related to a surface conformation where phenyl rings are mostly perpendicular to the substrate.