Ion Mobility Mass Spectrometry: The design of a new high-resolution ion mobility instrument with applications toward electronic-state characterization of first-row transition metal cations

The design of an instrument that couples a 2-m-long, high-resolution ion mobility drift tube with a quadrupole mass spectrometer is described. The system has been designed to be capable of separating/resolving ionic species having collision cross sections that differ by approximately 1%. Ion funnels are positioned at both the entrance and exit of the drift tube to maximize ion transmission into and out of the drift region of the system. The quadrupole mass analyzer has a mass range of m / z = 1–500. To characterize the performance of the instrument, the reduced mobilities for both the ground-state and electronic excited-state configurations of the first-row transition metal cations have been measured. The results obtained are compared to reduced mobilities previously reported. In all cases, ions were generated using pulsed-laser vaporization of metal targets. The reduced mobility of Sc + is presented here for the first time. A discussion of the relative merits of short and long drift–length mobility instruments is included, as well as an examination of the accuracy expected in the present instrument.