A new ion funnel for improving the transmission of low mass ions

Abstract

To solve the problem of low mass ion discrimination of conventional ion funnel and optimize ion transmission, a new ion funnel with a quadrupolar electrode configuration, was evaluated, based on the theoretical modeling, in this paper. The theoretical model was constructed by using the SIMION and the performance characteristics of the new ion funnel was simulated systematically by calculating the ion trajectory under different operating conditions. As the low mass ions lossed at the exit of ion funnel was mainly due to the opposite phase radio frequency (RF) voltage applied to the front and rear electrodes, the new ion funnel configuration rotated RF by 90 degrees and suppressed the axial potential wells near the ion funnel exit. The transmission efficiencies of the conventional and the new ion funnels for ions with low mass to charge ratio (m/z) were compared under the same operating conditions. The results showed that the new ion funnel configuration could improve the transmission efficiency by about 10% as compared to the conventional ion funnel in the m/z range below 70 while there was little differences in the transmission efficiency for high m/z ions.