OPEN TRAPPED ION CELL GEOMETRIES FOR FOURIER-TRANSFORM ION-CYCLOTRON RESONANCE MASS-SPECTROMETRY
OPEN TRAPPED ION CELL GEOMETRIES FOR FOURIER-TRANSFORM ION-CYCLOTRON RESONANCE MASS-SPECTROMETRY
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DOI：
10.1016/0168-1176(92)80006-m
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发表时间：
1992-01-15
期刊：
影响因子：
--
通讯作者：
LAUDE, DA
中科院分区：
文献类型：
--
作者：
BEU, SC;LAUDE, DA
傅里叶变换离子回旋共振质谱在捕获离子池中进行评估，捕获离子池用开放式矩形捕获电极代替垂直于磁场定位的捕获板。 与封闭电池相比，开放电池几何形状提供了更好的电池内部通道，对于外部离子注入具有明显的好处。 沿开式电池 z 轴中心线的井深度约为立方体几何形状所施加电势的 37%，但对于纵横比为 2 的细长电池，该深度增加至 81%。 创建等势场图是为了比较开放和封闭正交晶胞的捕获和激发场的轴向和径向分量。 开放电池中心的径向捕获电场稍大，但轴向激发场比封闭电池小两倍。 构建了长宽比为 2 的开放式细长单元，并将其与类似长宽比的封闭单元进行了比较。 实验上，与封闭单元的 - 32 Hz V-1 偏移相比，开放单元由于径向捕获场而获得了回旋加速器频率的 - 57 Hz V-1 偏移。 然而，与闭孔相比，开孔中的轴向喷射显着减少。 给出了将开放电池推广到多段电极组件的建议，其中激发、检测和捕获用相同的电极可互换地进行。 例如，建议将激发电位电容耦合到陷阱电极作为消除激发期间轴向喷射的简单方法。
Fourier transform ion cyclotron resonance mass spectrometry is evaluated in trapped ion cells which substitute open rectangular trapping electrodes for trapping plates positioned perpendicular to the magnetic field. Compared with closed cells, the open cell geometry offers improved access to the cell interior with obvious benefits for external ion injection. The well depth along the z-axis centerline of the open cell is about 37% of the applied potential for cubic geometry but increases to 81% for an elongated cell with aspect ratio two. Isopotential field maps are created to compare axial and radial components of trapping and excitation fields for open and closed orthorhombic cells. Radial trapping electric fields are somewhat larger in the center of the open cells but axial excitation fields are a factor of two smaller compared with the closed cell. An open elongated cell with an aspect ratio of two is constructed and compared with a closed cell of similar aspect ratio. Experimentally, a - 57 Hz V-1 shift in cyclotron frequency owing to the radial trapping field is obtained for the open cell compared with a - 32 Hz V-1 shift for the closed cell. However, axial ejection is significantly reduced in the open cell compared with the closed cell. Suggestions are given for generalizing the open cell to a multisegmented electrode assembly in which excitation, detection and trapping are performed interchangeably with the same electrodes. For example, capacitive coupling of the excitation potential to the trap electrodes is suggested as a simple means of eliminating axial ejection during excitation.