MULTIPLICITIES OF SECONDARY IONS EMITTED IN MACROMOLECULAR ION IMPACTEVENTS

A multiply-charged macromolecular accelerator (MUMMA) consisting of an electrospray ion source and a quadrupole mass spectrometer is employe d in studies of secondary ion emission under bombardment by multiply-c harged macromolecular ions. A time-of-flight (TOF) mass spectrometer i s interfaced to the MUMMA for analysis of the secondary ions originati ng from collision events of the primary ions with different targets. T he 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 ejectio n in a single macromolecular ion impact event are reported. The depend ence of the total secondary ion multiplicities on the projectile ion m ass and velocity provides the basis of a phenomenological model for se condary ion ejection by multiply-charged macromolecular ions.