| 摘要 |
PURPOSE:To improve the dynamic range in the stage of data acquisition by changing over and setting alternately the gain of a secondary electron multiplier to >=2 kinds of preliminarily selected and set values at every prescribed time. CONSTITUTION:The ions ionized by an ion source 1 pass through an exit slit 2 and are subjected to energy selection in an electric field 3; thereafter the ions are mass-dispersed in a magnetic field 4. The ions having specific mass number pass through a collector slit 5 and the signal is amplified by the secondary electron multiplier 6. The amplified signal is detected by a detector 7. The magnetic field is therefore continuously swept from 0 to the specific value by a magnetic field power source 8 in order to obtain mass spectra. The measurement is changed over and repeated by multivoltages 9 which are varied at every measuring point of chromatographic peaks by a CPU control device 10. The gain of the multiplier 6 is thus changed and the dynamic range is expanded. |
