ANALYSIS OF POLYMER SURFACES BY SIMS-17 - AN ASSESSMENT OF THE ACCURACY OF THE MASS ASSIGNMENT USING A HIGH-MASS RESOLUTION TOF-SIMS INSTRUMENT

The prospects for obtaining highly accurate mass assignments in polymer surface studies using state-of-the-art time-of-flight secondary ion mass spectrometry (ToF-SIMS) have been investigated systematically. For a thick film of poly(ethylene terephthalate) (PET), the reproducibility of mass measurement in both positive ion (range m/z = 0-600) and negative ion (range mit 0-350) modes has been studied in statistical fashion over a period of several months. Glyceryl monostearate, representing a typical polymer additive, was studied both on PET and as a very thin film on aluminum in order to compare the behavior of insulating and conducting samples. The effect of different mass calibration strategies (including use of atomic and molecular species), mass interferences and metastable peaks on mass accuracy also have been investigated. Finally, the importance of peak intensity for mass resolution and achievable mass accuracy has been determined. The results show that a useful mass accuracy of better than 20 ppm can be achieved over a mass range m/z = 0-600 for these polymer film surface studies under routine operating conditions.