Salazar Gary A, Masujima Tsutomu
Analytical Molecular Medicine and Devices Laboratory, Faculty of Frontier Medical Sciences, Graduate School of Hiroshima University, Minami-ku, Hiroshima, Japan.
J Am Soc Mass Spectrom. 2008 Sep;19(9):1367-74. doi: 10.1016/j.jasms.2008.05.022. Epub 2008 Jun 11.
The behavior of a completely new ion trap is shown with SIMION 7.0 simulations. The simulated trap, which was a mix of a linear and a 3D trap, was made by axially setting two ion guides with a gap between them. Each guide consisted of three rods with three symmetrically delayed radio frequency (rf) voltages (tripole). The "injected" ions were linearly contained by pulsed potentials on the entrance and exit plates. Then the three-dimensional (3D) rf field in the gap, which was created by the tripole special rod arrangement, could trap the ions when the translational energy was dampened by collisions with low-pressure nitrogen. Because the injected ions were trapped in the small gap, the trapping cycle could be repeated many times before ion ejection, so a high concentrated ion cloud could be obtained. This trapping and accumulation methodology is not possible in most conventional multipole linear traps with even number of poles. Compared with quadrupole linear trap at the same rf amplitude, tripole lost more ions due to strong charge repulsion in the ion cloud. However, tripole could catch up the ions at higher voltage. Radial and axial mass-independent ejection of the ions localized in the tripole gap was very simple, compared with conventional linear ion traps that need extra and complicated electrodes for effective axial ejection.
利用SIMION 7.0模拟展示了一种全新离子阱的行为。模拟的离子阱是线性阱和三维阱的混合体，通过轴向设置两个离子导向器并在它们之间留出间隙制成。每个导向器由带有三个对称延迟射频（rf）电压的三根杆组成（三极）。“注入”的离子通过入口和出口板上的脉冲电势被线性约束。然后，由三极特殊杆排列产生的间隙中的三维（3D）rf场，当平移能量因与低压氮气碰撞而衰减时，可以捕获离子。由于注入的离子被困在小间隙中，在离子射出之前捕获循环可以重复多次，因此可以获得高浓度的离子云。这种捕获和积累方法在大多数具有偶数极的传统多极线性阱中是不可能实现的。与相同射频幅度下的四极线性阱相比，三极由于离子云中强烈的电荷排斥而损失更多离子。然而，三极在更高电压下可以捕获离子。与需要额外复杂电极进行有效轴向射出的传统线性离子阱相比，位于三极间隙中的离子的径向和轴向质量无关射出非常简单。
