| 摘要 |
An isotopic-ratio mass spec- trometer comprises an r.f, or micro- wave induced plasma ion source (1, 2, 3), an electrostatic ion-energy ana- lyzer (75), a magnetic sector ion-mo- mentum analyzer (82) wherein ions are dispersed at a first potential ac- cording to their mass-to-charge ra- tios, and two or more ion collectors (77) for receiving ions of different mass-to-charge ratios, wherein an apertured electrically conductive sampling member (19) is provided adjacent to the plasma (3) and com- municates between the plasma and a first vacuum enclosure (23) evacuat- ed by first pumping means (25); an apertured skimmer member (28) sep- arates the first vacuum enclosure from a second vacuum enclosure (4) evacuated by second pumping means (5); an apertured differential pump- ing member (6) separates the second vacuum enclosure from a third vacuum enclosure (7) evacuated by third pumpin g means (43); an apertured analyzer entrance member (46) separates the third vacuum enclosure from a vacuum envelope (75, 76, 77) in which the electrostatic ion-energy ana- lyzer, ion-momentum analyzer, and ion detectors are disposed, the vacuum envelope being evacuated by fourth pumping means (131); and means (40) are provided for maintaining the sampling member at a second potential whereby ions generated in the plasma passthrough each of the apertures and are accelerated to have a kinetic energy suitable for their mass analysis in the ion- momentum analyzer at said first potential.
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