Secondary ion formation from functional polymer systems in static secondary ion mass spectrometry

Abstract

The process of emission of structurally related secondary ions from functional polymers under keV ion bombardment is investigated. Competition between ion formation mechanisms is apparent in static SIMS analysis of functionalized polymer systems. Complementary positive and negative “ion pair” emission is favorable when the fragmentation of the polymer structure results in charge stabilized ions. These processes are illustrated by SIMS analysis of poly(aryl methacrylates) and by comparison to previous laser desorption mass spectrometry results of the same materials. The generation of n-mer fragment ions, from bond breaking along the chain of a polymer, is illustrated by the analysis of a series of functionalized nitrogen containing polymers and from poly(styrene sulfonic acid). In these cases, pre-existing localized charge at the surface of a polymer has a direct effect on the measured peak intensities and the presence or absence of structurally related ions. The analysis of polymeric surface reactivity due to different solid state isomeric structures at the surface is investigated through the surface modification of isomeric poly(vinyl pyridines) (P2VP and P4VP). This allows for differentiation of these systems as well as insight into the extent of static SIMS primary ion modification of the material under analysis.