| 摘要 |
<p>A mass spectrometer comprising ion source means (1) for producing ions characteristic of a sample to be analysed; ion detector means (14) for receiving at least some of said ions; magnetic sector analyzing means (18) and electrostatic analyzing means (8) disposed in any order between said ion source means (1) and said ion detector means (14); wherein said magnetic sector analyzing means (18) comprises means for dispersing ions according to their mass-to-charge ratios and for transmitting ions whose mass-to-charge ratios lie within a predetermined range and have a first kinetic energy; said electrostatic analyzing means (8) comprises means for generating an electrostatic field for deflecting ions having different kinetic energies around different curved trajectories such that ions having a second kinetic energy, lower than said first kinetic energy, are deflected around a central curved trajectory (15) and transmitted through said electrostatic analyzing means (8), and the strength of said electrostatic field is substantially equal to the strength of a similar reference field multiplied by the ratio of said second and said first kinetic energies when the strength of said reference field is that necessary to deflect ions having said first kinetic energy around said central curved trajectory (15); and means (11) are provided prior to said magnetic sector analyzing means for changing the kinetic energy of ions to said first kinetic energy and (4) prior to said electrostatic analyzing means for changing the kinetic energy of ions to said second kinetic energy. <IMAGE></p> |
