DIRECT EMISSION OF MOLECULAR FRAGMENTS DURING THE SPUTTERING OF POLY(4-HYDROXYSTYRENE) AND DETERMINATION OF ION STRUCTURES USING TANDEM SECONDARY ION MASS-SPECTROMETRY

Poly(4-hydroxystyrene) (P4HS) has been studied using a tandem secondary ion mass spectrometer under static conditions. The secondary ion mass spectrometry (SIMS) spectrum of P4HS exhibits few ions which are not observed in the SIMS spectrum of polystyrene. The fragmentation of these oxygen-containing ions has been investigated in detail and the relevant neutral losses have been deduced. These ions are found to have structures based upon either the tropyllium ion or the styrene ion. The absence of other oxygen-containing ions is explained in terms of the ready loss of oxygen-containing neutral fragments from P4HS compared with the loss of hydrocarbon fragments. The oxygen-containing tropyllium and styrene ions are, in contrast, readily formed, and in these cases the energy barrier to formation of the oxygen-containing ion is less than the energy barrier to expulsion of oxygen-containing neutral species.