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The stability diagram with some ions under trapping parameters used for this work

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posted on 2013-09-06, 00:00 authored by C Kyriakides, B S Clarke, V H S Kwong

Figure 1. The stability diagram with some ions under trapping parameters used for this work. The coordinates az and qz are dependent on the ion's m/q, the rf potential's frequency (Ω0), amplitude (V0) and offset (U0) as well as the trap's length and radius (2z0 and r0). They are given by a_{z}=\displaystyle\frac{-16qU_{0}}{m\left(r_{0}^{2}+2z_{0}^{2}\right)\Omega _{0}^{2}}\quad { \rm and \quad }q_{z}=\frac{8qV_{0}}{m\left(r_{0}^{2}+2z_{0}^{2}\right)\Omega _{0}^{2}}. The ion's m/q value is also indicated. Only ions with m/q inside the region labelled stable will remain inside the trap. The first two sets of rf amplitude, frequency and dc offset, • and ▪, respectively, are used to eliminate the unwanted ions as m/q = 1, 2 and higher are placed well outside the stable regions. The eliminated ions will affect the intensity of the stored ion of interest (m/q = 1.5). In the final (third) set,, the ion of interest now free of the unwanted ions is stored under optimum conditions.


We report our measured values for the sum of single and double charge transfer rate coefficients between 3He2 + and H2, CH4, N2 and CO. Our values are 2.4 ± 0.2 × 10−9 cm3 s−1 for H2, 6.3 ± 0.9 × 10−9 cm3 s−1 for CH4, 4.0 ± 0.3 × 10−9 cm3 s−1 for N2 and 4.7 ± 0.4 × 10−9 cm3 s−1 for CO. The values are obtained at equivalent temperatures of 1200–2400 K.


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