Method and apparatus for ejecting unwanted ions in an ion trap mass spectrometer

Claim 1

An ion trap mass spectrometer apparatus comprising: an ion trap having a plurality of electrodes, means for establishing ion trapping fields within said ion trap for trapping ions over a predetermined mass range, ion excitation means for resonantly ejecting ions trapped in said ion trap including: means for determining a plurality of spaced discrete frequencies covering the range of frequencies of the characteristic motion of ions which are to be resonantly ejected from the ion trap, means for processing said discrete frequencies to generate a plurality of time dependent voltage amplitude values which vary throughout the time domain such that the frequency content of said time dependent voltage amplitude values is relatively uniform over the entire time domain, and such that the magnitude of the discrete frequencies is relatively uniform over the frequency domain, and means for applying said time dependent voltage amplitude values to said ion trap electrodes whereby to resonantly eject said ions.

Claim 11

A method for resonantly ejecting ions stored in an ion trap comprising the steps of determining a plurality of spaced discrete frequencies covering the range of frequencies of characteristic motion of the ions which are to be resonantly ejected, processing said discrete frequencies to generate a plurality of time dependent voltage amplitude values which vary throughout the time domain such that the frequency content of said time dependent voltage amplitude values is relatively uniform over the entire time domain, and such that the magnitude of the discrete frequencies is relatively uniform over the frequency domain, and applying said time dependent voltage amplitude values to said ion trap electrodes whereby to resonantly eject said ions.

Claim 12

A method for resonantly ejecting ions stored in an ion trap comprising the steps of determining a plurality of spaced discrete frequencies covering the range of frequencies of characteristic motion of the ions which are to be resonantly ejected, processing said discrete frequencies to generate a plurality of time dependent voltage amplitude values which vary throughout the time domain such that the frequency content of said time dependent voltage amplitude values is relatively uniform over the entire time domain, and such that the magnitude of the discrete frequencies is relatively uniform over the frequency domain, and applying said time dependent voltage amplitude values to said ion trap electrodes whereby to resonantly eject said ions.

Claim 16

A method for resonantly ejecting ions stored in the ion trap of a mass spectrometer which stores ions over a predetermined mass range including the steps of: determining a series of spaced sine functions which have phases that vary non-linearly with frequency, said sine functions covering the range of frequencies of the characteristic motion of ions to be ejected, summing the series of sine functions to provide a waveform which has a series of closely spaced discretely separated peaks in the frequency domain, such that the difference in ejection efficiency between an ion having a characteristic frequency of motion which coincides with a discrete frequency component of the waveform, and an ion having a characteristic frequency of motion which falls between the discrete frequency components of the waveform is small, and applying said waveform to the ion trap to resonantly eject selected ions.

Claim 17

A method for resonantly ejecting ions stored in the ion trap of a mass spectrometer which stores ions over a predetermined mass range including the steps of: determining a series of spaced sine functions which have phases that vary non-linearly with frequency, said sine functions covering the range of frequencies of the characteristic motion of ions to be ejected, summing the series of sine functions to provide a waveform which has a series of closely spaced discretely separated peaks in the frequency domain, such that the difference in ejection efficiency between an ion having a characteristic frequency of motion which coincides with a discrete frequency component of the waveform, and an ion having a characteristic frequency of motion which falls between the discrete frequency components of the waveform is small, and applying said waveform to the ion trap to resonantly eject selected ions.

Claim 18

A method for resonantly ejecting ions stored in an ion trap including the steps of: determining a series of spaced sine functions which have phases that vary non-linearly with frequency, said sine functions covering the range of frequencies of the characteristic motion of ions to be ejected, summing the series of sine functions to provide a waveform which has a series of spaced discretely separated peaks in the frequency domain, such that the difference in frequencies between successive discretely separated peaks in the frequency domain is at least four times the reciprocal of the time interval over which the waveform is to be applied, and applying said waveform to the ion trap to resonantly eject selected ions.

Claim 19

A method for resonantly ejecting ions stored in an ion trap including the steps of: determining a series of spaced sine functions which have phases that vary non-linearly with frequency, said sine functions covering the range of frequencies of the characteristic motion of ions to be ejected, summing the series of sine functions to provide a waveform which has a series of spaced discretely separated peaks in the frequency domain, such that the difference in frequencies between successive discretely separated peaks in the frequency domain is at least four times the reciprocal of the time interval over which the waveform is to be applied, and applying said waveform to the ion trap to resonantly eject selected ions.

Claim 20

A method for resonantly ejecting ions stored in an ion trap including the steps of: determining a series of spaced sine functions which have phases that vary non-linearly with frequency, said sine functions covering the range of frequencies of the characteristic motion of ions to be ejected, summing the series of sine functions to provide a waveform which has a series of spaced discretely separated peaks in the frequency domain, such that the difference in frequencies between successive discretely separated peaks in the frequency domain is at least two times the reciprocal of the time interval over which the waveform is to be applied, and applying said waveform to the ion trap to resonantly eject selected ions.

Claim 21

A method for resonantly ejecting ions stored in an ion trap including the steps of: determining a series of spaced sine functions which have phases that vary non-linearly with frequency, said sine functions covering the range of frequencies of the characteristic motion of ions to be ejected, summing the series of sine functions to provide a waveform which has a series of spaced discretely separated peaks in the frequency domain, such that the difference in frequencies between successive discretely separated peaks in the frequency domain is at least two times the reciprocal of the time interval over which the waveform is to be applied, and applying said waveform to the ion trap to resonantly eject selected ions.

Claim 26

A method for resonantly ejecting ions stored in an ion trap including the steps of: calculating a waveform in which the magnitude part of the frequency spectrum is assigned in such a way that the frequency spectrum substantially consists of a series of discretely separated peaks covering a range of frequencies corresponding to the characteristic frequencies of ions to be ejected and in which the phase part of the frequency spectrum is assigned as a nonlinear function of frequency and in which the time domain waveform is calculated by application of the inverse Fourier transform, and applying said waveform to the ion trap to resonantly eject selected ions.

Claim 27

A method for resonantly ejecting ions stored in an ion trap including the steps of: calculating a waveform in which the magnitude part of the frequency spectrum is assigned in such a way that the frequency spectrum substantially consists of a series of discretely separated peaks covering a range of frequencies corresponding to the characteristic frequencies of ions to be ejected and in which the phase part of the frequency spectrum is assigned as a nonlinear function of frequency and in which the time domain waveform is calculated by application of the inverse Fourier transform, and applying said waveform to the ion trap to resonantly eject selected ions.

Claim 28

A method for resonantly ejecting ions stored in an ion trap including the steps of: calculating a waveform in which the magnitude part of the frequency spectrum is assigned in such a way that the frequency spectrum substantially consists of a series of discretely separated peaks covering a range of frequencies corresponding to the characteristic frequencies of ions to be ejected and such that the difference in frequencies between the successive peaks in the frequency domain is at least four times the reciprocal of the time interval over which the waveform is to be applied, and in which the phase part of the frequency spectrum is assigned as a nonlinear function of frequency and in which the time domain waveform is calculated by application of the inverse Fourier transform, and applying said waveform to the ion trap to resonantly eject selected ions.

Claim 29

A method for resonantly ejecting ions stored in an ion trap including the steps of: calculating a waveform in which the magnitude part of the frequency spectrum is assigned in such a way that the frequency spectrum substantially consists of a series of discretely separated peaks covering a range of frequencies corresponding to the characteristic frequencies of ions to be ejected and such that the difference in frequencies between the successive peaks in the frequency domain is at least four times the reciprocal of the time interval over which the waveform is to be applied, and in which the phase part of the frequency spectrum is assigned as a nonlinear function of frequency and in which the time domain waveform is calculated by application of the inverse Fourier transform, and applying said waveform to the ion trap to resonantly eject selected ions.

Claim 30

A method for resonantly ejecting ions stored in an ion trap including the steps of: calculating a waveform in which the magnitude part of the frequency spectrum is assigned in such a way that the frequency spectrum substantially consists of a series of discretely separated peaks covering a range of frequencies corresponding to the characteristic frequencies of ions to be ejected and such that the difference in frequencies between the successive peaks in the frequency domain is at least two times the reciprocal of the time interval over which the waveform is to be applied, and in which the phase part of the frequency spectrum is assigned as a nonlinear function of frequency and in which the time domain waveform is calculated by application of the inverse Fourier transform, and applying said waveform to the ion trap to resonantly eject selected ions.

Claim 31

A method for resonantly ejecting ions stored in an ion trap including the steps of: calculating a waveform in which the magnitude part of the frequency spectrum is assigned in such a way that the frequency spectrum substantially consists of a series of discretely separated peaks covering a range of frequencies corresponding to the characteristic frequencies of ions to be ejected and such that the difference in frequencies between the successive peaks in the frequency domain is at least two times the reciprocal of the time interval over which the waveform is to be applied, and in which the phase part of the frequency spectrum is assigned as a nonlinear function of frequency and in which the time domain waveform is calculated by application of the inverse Fourier transform, and applying said waveform to the ion trap to resonantly eject selected ions.

Claim 32

A method for resonantly ejecting ions stored in an ion trap including the steps of: calculating a waveform in which the magnitude part of the frequency spectrum is substantially a series of discretely separated peaks covering a range of frequencies corresponding to the characteristic frequencies of ions to be ejected, and applying said waveform to the ion trap to resonantly eject selected ions.

Claim 33

A method for resonantly ejecting ions stored in an ion trap including the steps of: calculating a waveform in which the magnitude part of the frequency spectrum is substantially a series of discretely separated peaks covering a range of frequencies corresponding to the characteristic frequencies of ions to be ejected, and applying said waveform to the ion trap to resonantly eject selected ions.

Claim 34

A method for resonantly ejecting ions stored in an ion trap including the steps of: calculating a waveform in which the magnitude part of the frequency spectrum substantially consists of a series of discretely separated peaks covering a range of frequencies corresponding to the characteristic frequencies of ions to be ejected and such that the difference in frequencies between the successive peaks in the frequency domain is at least four times the reciprocal of the time interval over which the waveform is to be applied, and p1 applying said waveform to the ion trap to resonantly eject selected ions.

Claim 35

A method for resonantly ejecting ions stored in an ion trap including the steps of: calculating a waveform in which the magnitude part of the frequency spectrum substantially consists of a series of discretely separated peaks covering a range of frequencies corresponding to the characteristic frequencies of ions to be ejected and such that the difference in frequencies between the successive peaks in the frequency domain is at least four times the reciprocal of the time interval over which the waveform is to be applied, and p1 applying said waveform to the ion trap to resonantly eject selected ions.

Claim 36

A method for resonantly ejecting ions stored in an ion trap including the steps of: calculating a waveform in which the magnitude part of the frequency spectrum substantially consists of a series of discretely separated peaks covering a range of frequencies corresponding to the characteristic frequencies of ions to be ejected and such that the difference in frequencies between the successive peaks in the frequency domain is at least two times the reciprocal of the time interval over which the waveform is to be applied, and applying said waveform to the ion trap to resonantly eject selected ions.

Claim 37

A method for resonantly ejecting ions stored in an ion trap including the steps of: calculating a waveform in which the magnitude part of the frequency spectrum substantially consists of a series of discretely separated peaks covering a range of frequencies corresponding to the characteristic frequencies of ions to be ejected and such that the difference in frequencies between the successive peaks in the frequency domain is at least two times the reciprocal of the time interval over which the waveform is to be applied, and applying said waveform to the ion trap to resonantly eject selected ions.