Mass Spectrometer
First Claim
1. A mass spectrometer having an ion optical system for transporting ions to a next stage, which is characterized in that the ion optical system includes:
- a) a virtual multipole rod ion optical element having 2×
N pieces of virtual rod electrodes (where N is an integer equal to or greater than two) arranged so as to surround an ion beam axis, each virtual rod electrode being composed of M pieces of plate electrodes spaced along the ion beam axis (where M is an integer equal to or greater than three); and
b) a voltage-applying means for applying radio-frequency voltages in a following manner;
in each set of the 2×
N plate electrodes arranged around the ion beam axis, a same radio-frequency voltage is applied to any two plate electrodes opposing each other across the ion beam axis, and two radio-frequency voltages having a same amplitude and a phase difference of 180 degrees are respectively applied to any two plate electrodes neighboring each other around the ion beam axis; and
in each set of the M plate electrodes forming one virtual rod electrode, a phase of the radio-frequency voltage applied to at least one of the plate electrodes is different from a phase of the radio-frequency voltage applied to another plate electrode.
1 Assignment
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Accused Products
Abstract
One virtual rod electrode (11) is composed by arraying a plurality of plate electrodes (111, . . . , 118) along an ion beam axis, and a quadrupole ion optical element (1) is constructed by arranging four virtual rod electrodes (11, 12, 13 and 14) around an ion beam axis C. A voltage-applying unit alternately applies two radio-frequency voltages having a phase difference of 180 degrees for each of the plate electrodes in one virtual rod electrode. By this voltage application, the quadrupole component of the radio-frequency electric field created within a space surrounded by the four virtual rod electrodes is decreased, while higher-order multipole components are increased. The quadrupole component yields high ion convergence and mass selectivity, while the higher-order components provide high ion transmission efficiency and ion acceptance. The general ion transport efficiency can be improved by appropriately adjusting the ion optical characteristics according to the installation environment of the ion optical system and the conditions before and after the ion optical system.
25 Citations
14 Claims
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1. A mass spectrometer having an ion optical system for transporting ions to a next stage, which is characterized in that the ion optical system includes:
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a) a virtual multipole rod ion optical element having 2×
N pieces of virtual rod electrodes (where N is an integer equal to or greater than two) arranged so as to surround an ion beam axis, each virtual rod electrode being composed of M pieces of plate electrodes spaced along the ion beam axis (where M is an integer equal to or greater than three); andb) a voltage-applying means for applying radio-frequency voltages in a following manner;
in each set of the 2×
N plate electrodes arranged around the ion beam axis, a same radio-frequency voltage is applied to any two plate electrodes opposing each other across the ion beam axis, and two radio-frequency voltages having a same amplitude and a phase difference of 180 degrees are respectively applied to any two plate electrodes neighboring each other around the ion beam axis; and
in each set of the M plate electrodes forming one virtual rod electrode, a phase of the radio-frequency voltage applied to at least one of the plate electrodes is different from a phase of the radio-frequency voltage applied to another plate electrode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification