DIMERIZATION OF POLYSTYRENE DURING STATIC SIMS MEASUREMENTS

In this work we report on the results of some static time-of-flight se condary ion mass spectrometry (TOF-SIMS) experiments performed on low- molecular-weight narrow distribution polystyrene. Evidence of cross-li nking during analysis is found, as indicated by the presence of peaks corresponding to molecules formed by linking of two initial polymer ch ains. The effect, which can be easily taken into account, does not app reciably affect the molecular weight distribution parameters obtained. However, the observed phenomenon gives the indication that, at least in the case of particularly sensitive systems, ion beam-induced modifi cation can occur also in static SIMS experiments. In addition, the obs erved phenomenon can be of relevance in modelling the sputtering of la rge molecules.