Multiplicities of secondary ions emitted in macromolecular ion impact events

Abstract

A multiply-charged macromolecular accelerator (MUMMA) consisting of an electrospray ion source and a quadrupole mass spectrometer is employed in studies of secondary ion emission under bombardment by multiply-charged macromolecular ions. A time-of-flight (TOF) mass spectrometer is interfaced to the MUMMA for analysis of the secondary ions originating from collision events of the primary ions with different targets. The mass of the projectiles ranges from 1.1 to 66 kDa and their energy from 10 to 520 keV. Initial results on negative secondary ion ejection in a single macromolecular ion impact event are reported. The dependence of the total secondary ion multiplicities on the projectile ion mass and velocity provides the basis of a phenomenological model for secondary ion ejection by multiply-charged macromolecular ions.