SynopsisNegative secondary ion mass spectra of poly(methylmethacry1ate) (PMMA), poly(ethy1methacrylate) (PEMA), and two copolymers of methylmethacrylate (MMA) and ethylmethacrylate (EMA) are presented. The spectra were obtained with a time of flight-static secondary ion mass spectrometer without charge compensation. The structures of typical ions in the mass range 20-220 amu are given, and the intensities of these ions were used to obtain some quantitative information about the ion formation processes. It is shown that quantification of a simple two-component system like the copolymers mentioned above is rather straightforward.