Patent ID: 6852971
Filing Date: 2005-02-08
Classification: H01J

Abstract:
1. A charge-reducing device comprising: a sample ion source which generates multiple-charged sample ions; first and second linear ion traps arranged in series; an AC power supply system which supplies a dipole AC electric field to said first linear ion trap; an opposite-charged ion source which generates opposite-charged ions with respect to said multiple-charged sample ions; wherein said multiple-charged sample ions are introduced into said first and second linear ion traps, and said multiple-charged sample ions in said first and second linear ion traps lose kinetic energy by collision with a gas filling said first and second linear ion traps; wherein said multiple-charged sample ions in said second linear ion traps are transferred to said first linear ion trap; and wherein said opposite-charged ions are introduced into said first linear ion trap upon condition that, to said opposite-charged ions, an electrostatic potential of said second linear ion trap is set higher than an electrostatic potential of said first linear ion trap such that said opposite-charged ions are not introduced into said second linear ion trap and a charge-reducing reaction between said opposite-charged ions and said multiple-charged sample ions takes place in said first linear ion trap and said charge-reducing reaction does not take place in said second linear ion trap, and upon condition that said dipole AC electric field, having a frequency of a secular motion of charge-reduced ions by said charge-reducing reaction or having a frequency band including a frequency of a secular motion of said charge-reduced ions, is applied to said first linear ion trap by said AC power supply system such that said charge-reduced ions excited selectively by said dipole AC electric field are selectively transferred to said second linear ion trap from said first linear ion trap.