| 摘要 |
PURPOSE:To provide an adequate scanning width for any mass and to permit sure centering by varying the mass scanning width in centering of a peak according to mass. CONSTITUTION:An ion accelerating voltage is set at VO, and the magnetic field of a magnet 1 is set at a calculated value BO so that the ion of mass MO is detected with a detector 4. A standard sample is then introduced into an ion source 2 and the ion of the mass MO is detected with the detector 4, the detected signal thereof is fed to a CPU5. The excitation of the magnet 1 is swept in a small range around the BO. The CPU5 detects the change in the ion detection signal in this stage and stops sweeping the magnet excitation in the place where the ion detection signal is max. The CPU holds the excitation in said stage. The ion accelerating voltage when a measuring sample is introduced into the ion source is set at the calculated value V1 for the ion of mass M1 to be detected. The ion accelerating voltage is swept in a range of a specified width DELTAV around the V1, and the point where the ion detection signal is max. is detected with the CPU5, by which the ion accelerating voltage is fixed. |
