title: Two stability islands of quadrupole mass filter near q = 0.9 created by auxiliary radio frequency voltage.
abstract: We report the numerical investigations of quadrupole mass filters concerning stability islands created by auxiliary radio frequency (RF) voltage with high and low frequencies near q = 0.9. The islands are located along the q axis near boundary value q = 0.908 with a low a parameter. The analysis is based upon the matrix method for stability diagram calculations and ion trajectory numerical simulation. The trajectory of ion motions is generated using Runge-Kutta-Nystrom-Dormand-Prince (RK-N-DP) order integration. The ion source model with Gaussian distribution of initial positions and transverse velocities is used. In RF-only operation mode, a resolution power of about R(0.1) = 600 without peak tails is achieved with a separation time of about 50 RF cycles. Relatively high resolution power of about 2000-3000 is observed in DC+RF separation mode with a low frequency auxiliary RF signal. The boundaries of stability diagram for additional RF voltage with high frequency are strongly diffused until the separation time is increased up to n = 300 RF cycles. The strong influence of phase shifts between main drive RF voltage and small auxiliary RF voltage on transmission is also examined. In DC + RF mode, the period of transmission varies with phase shift of pi or one period of the main drive RF voltage; and in RF-only mode this period is pi/2.
authors: Department of Chemistry, Fudan University, 220 Handan Road, Shanghai, 200433, China.
authors: Chan
authors: C
authors: Luo
authors: Gongyu
authors: G
authors: Jiang
authors: Nikolai V
authors: NV
authors: Konenkov
authors: Chuanfan
authors: C
authors: Ding