| 摘要 |
An improved ion detection system and method for detection of low or high mass ions. A target having a low work function, photoemissive surface layer is employed to fragment the incident ions and produce secondary negative ions and electrons. The target surface preferably is formed of a thin layer of an alkali antimonide compound, bialkali antimonide compound, multi-alkali antimonide compound, cesiated III - V semiconductor compound, or other photoemissive material having a relatively low band gap energy and electron affinity. Additionally, the photoemissive material should have a low thermionic emission level at room temperature to reduce noise levels in the detector. The secondary ions and electrons may be detected by a conventional electron multiplier detector. The potential difference between the target surface and electron multiplier detector is chosen to accelerate the secondary ions and electrons to the electron multiplier detector with an energy corresponding to high detection efficiency.
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