Implementation of a Penning ionization source on a FTICR instrument with ion funnel optics

Abstract

A Qh-FT-ICR equipped with an electrospray source has been recently coupled, in our laboratory, with a metastable atom bombardment (MAB) source. In this Penning ionization source, the gas phase sample is bombarded with a beam of metastable atoms in vacuum. Compared to EI, the MAB source allows the control of the internal energy and selective ionization by the use of different gases (rare gases and N 2). The FT-ICR provides accurate mass measurements thanks to its ultra-high resolution. After the adaptation of the MAB/EI source and its implementation in the FT-ICR instrument, several optimizations were carried out in order to obtain a detectable signal. The ion beam generated by the dual MAB/EI source was characterized through the study of ion kinetic energy distribution. The FTICR instrument was equipped initially with ESI source and ion funnel optics. The design of the optic lenses and applied potentials used for ions transmission from the homemade EI/MAB dual source to the ESI optics was developed using SIMION simulations. The RF and DC potentials applied to the ion funnels were tuned in order to achieve transmission of low m/ z ions with a pressure of 10 −3 mBar compared to the 1 mBar used in normal ESI operation.