A schematic of the Quadrupole-Cell-Quadrupole (QCQ) instrument is shown below. As with the MALDI-Sector instrument, a variety of ion sources can be used with this instrument. However, in recent years, the main focus of the experiments conducted on the QCQ instrument has been the study of the interactions of transition metal cluster ions with various neutral ligands. To accomplish this goal, the primary method used for ionization has been pulsed laser vaporization of a translating/rotating metal rod in an Ar bath gas. A XeCl excimer laser is used in the experiment operating at a wavelength of 308 nm with a power output of approximately 300 mJ/pulse.
    Clusters exiting the source are mass selected by the first quadrupole mass filter and injected into the drift/reaction cell. When conducting a mobility experiment, the cell is typically filled with 5 Torr of He. When temperature-dependent equilibrium data or time-dependent rate data is the focus of the experiment, the cell is filled with a gas mixture typically composed of 0.0015 - 0.5 Torr of reactant gas and 4.5 Torr of He. In some in cases, the cell is filled only with the reactant gas at pressures up to 5 Torr. Clusters exiting the cell are then mass selected by a second quadrupole mass filter and detected with an electron multiplier. The upper mass limit of the quadrupoles is approximately m/z = 1800. The QCQ cell has a temperature range of 80 - 800 K. Further details concerning this instrument can be found in Kemper, P. R.; Weis, P.; Bowers, M. T. Int. J. Mass Spectrom. Ion Proc. 1997, 160, 17-37.