| 摘要 |
PURPOSE:To obtain the constant ion-electron conversion efficiency accompanied with the change of sensitivity in the case where sensitivity can be varied, by installing a grid between an ion-electron conversion dinode and the electron input edge surface of a secondary electron multiplier and applying a constant electric potential. CONSTITUTION:The ion which passes through an ion outlet opened port 2 from a mass analyzing part 1 and is irradiated into the space between an ion-electron conversion dinode 3 and a grid 5 is bent downward, and irradiated to the dinode 3, and the secondary electrons are emitted from the surface. The electron passes through the screen of the grid 5 and is irradiated to the electron radiation edge surface of a secondary electron multiplier 4. This sensitivity can be varied according to the electric potential difference between the irradiation edge surface, and an electron catching electrode 41 can be shifted to the gland level, and the electron input edge surface can be shifted to a negative side. The electric field distribution in the space behind the opened port 2 is not changed because of the electric field shielding effect of the grid 5, and also the ion orbit is not changed, and also the ion catching efficiency of the dinode 3 is not changed. |
