Multipole ion trap as cluster-ion source

We have developed a new type of ion trap, an external multipole static attraction ion trap (EMSIT) for use as a cluster-ion source. The EMSIT consists of 36 linear pole electrodes of nearly equal length arranged in a 6x6 square lattice and a cylindrical cage electrode surrounding the pole edges. An ion-trapping field is generated between the multipole and the cage electrode by applying ac and dc voltages to the pole electrodes. Simulation results indicated that the EMSIT can confine the ions with a wide range of mass values in the ion-trapping field and act as a mass-selective ion source using the central four poles as an ion extraction guide. In fact, we observed that Xe+ ions were confined in the EMSIT for more than 1 s in the presence of He buffer gas of 5.0x10-2 Pa. Hydrogenated Si cluster ions, SinHx+ (n=2-6), were grown from SiH4 gas and extracted with mass selection, indicating that the EMSIT acts as a cluster-ion source. (author)