| 摘要 |
Ions supplied in the form of a pulse are introduced into an ion trap through an ion entering orifice while a rectangular voltage of a frequency higher than the frequency at which the best trap is accomplished is applied to a ring electrode from a trap voltage generating unit. With this, since a well of a pseudo ion potential is formed in a radial direction in the ion trap, the spread of ions of low m/z values introduced previously is suppressed. A part of ions is introduced into the ion trap, and thereafter the frequency of the rectangular voltage applied to the ring electrode is lowered stepwise to the frequency at which the best trap is accomplished. As a result, the ions of the low m/z values introduced previously can be efficiently trapped, and introduction of ions of high m/z values reaching the ion trap later is not hindered. Consequently, ions of a wide range of m/z values can be trapped in the ion trap with high efficiency |
