| 摘要 |
A detector for a time-of-flight mass spectrometer with high mass resolution for large masses (in the range of about ten thousand to several hundred thousand atomic mass units), comprises a convertor 2 for the conversion of large ions into smaller ions, which can then be detected with standard ion detectors for ions of smaller and average masses. The converter consists of a thin multichannel plate 2, such as is normally used for secondary-electron multiplication. However, in contrast to secondary-electron multiplication operation, it is operated at reversed polarity in order to produce large numbers of low-weight positive ions by a self-contained amplification process engaging secondary electrons accelerated in backward direction. These ions are detected by at least one further multichannel plate 3,4 in association with a collector 5 or scintillator (8). This device and operating method leads to a reduction in signal width and offer extremely high sensitivity for large ions. |
