Patent US2849241A successfully refreshed from Google Patents.
Patent US4761545A successfully refreshed from Google Patents.
US4761545A
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Tailored excitation for trapped ion mass spectrometry
Assignee: OHIO STATE UNIVERSITY RESEARCH FOUNDATION COLUMBUS OH AN OH NON-PROFIT ORG
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Filing: 1986-05-23
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Granted: 1988-08-02
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Expires: 2006-05-23
Abstract
Abstract An ion cyclotron resonance cell has applied thereto an excitation which has a time domain waveform which is the inverse Fourier transform of a frequency domain excitation spectrum which has been chosen by the user to yield selective excitation and/or suppression of ranges of ion mass-to-charge ratios. To minimize the dynamic range of the time domain signal resulting from the inverse Fourier transform, the phases of the various discrete frequency components in the frequency domain spectrum which are used in calculating the inverse Fourier transform are not constant but rather are varied as a function of the frequency of the components. The phase of each component is assigned such that the frequency components in the time domain signal are not all in phase at any point in time, thereby avoiding large magnitude spikes in the time domain waveform. The phases of the various frequency components may follow a non-linear function of the frequencies of the components, such as a quadratic function. By varying phase in this manner, the time domain signal which is applied to the excitation plates of the ion cyclotron resonance cell has a frequency domain power spectrum which is substantially flat over the specified band or bands of frequencies of interest. The time domain waveform may be shifted and/or weighted before being applied to the excitation plates. Tailored excitation may also be applied in this manner to the end plates of an ion trap cell to cause tailored ejection of specific bands or ranges of ions with retention of remaining ions within the cell.
Inventors
- 👤 Alan G. Marshall
- 👤 Tom L. Ricca
- 👤 Tao-Chin L. Wang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 15:20
CPC Classifications
H; H01; H01J; H01J49/00; H01J49/26; H01J49/34; H01J49/42; H01J49/4205; H01J49/424; H01J49/36; H01J49/38; H01J49/426; H01J49/427
Claims Analysis
Total Claims: 48
Claim 1
Independent Claim
114 words
Ion mass spectrometry apparatus comprising: (a) an ion cell including a plurality of electrode plates; (b) means for detecting motion of ions in the cell and providing a signal indicative thereof; (c) excitation means connected to the ion cell for producing an electric field in the cell which has a time domain waveform which is a selectively weighted and shifted inverse Fourier transform of components at discrete frequencies of a selected frequency domain excitation spectrum wherein the phases of the discrete frequency components are varied by the excitation means as a non-constant function of the frequencies of the components such that the frequency components are not all in phase at any point in time.
Claim 2
Dependent Claim
114 words
Ion mass spectrometry apparatus comprising: (a) an ion cell including a plurality of electrode plates; (b) means for detecting motion of ions in the cell and providing a signal indicative thereof; (c) excitation means connected to the ion cell for producing an electric field in the cell which has a time domain waveform which is a selectively weighted and shifted inverse Fourier transform of components at discrete frequencies of a selected frequency domain excitation spectrum wherein the phases of the discrete frequency components are varied by the excitation means as a non-constant function of the frequencies of the components such that the frequency components are not all in phase at any point in time.
Claim 3
Dependent Claim
25 words
The apparatus of claim 1 in which the phases of the discrete frequency components are varied by the excitation means as a non-linear, continuous function.
Claim 4
Dependent Claim
23 words
The apparatus of claim 2 wherein the phases of the discrete frequency components are varied by the excitation means as a quadratic function.
Claim 5
Dependent Claim
30 words
The apparatus of claim 1 wherein the phases of the discrete frequency components are varied by the excitation means as a nonlinear function of frequency having at least one discontinuity.
Claim 6
Dependent Claim
65 words
The apparatus of claim 1 wherein the excitation means includes means for mixing a first higher frequency carrier signal with a time domain signal which is the inverse Fourier transform of the selected frequency domain excitation spectrum and wherein the excitation means produces an electric field in the cell which varies in accordance with the first higher frequency signal modulated by the time domain signal.
Claim 7
Dependent Claim
54 words
The apparatus of claim 5 including means for mixing the signal indicative of an ion motion with a second higher frequency carrier signal to produce a mixed signal having sum and difference frequency components and including means for filtering the mixed signal to isolate the difference frequency components indicative of an ion resonance response.
Claim 8
Dependent Claim
127 words
The apparatus of claim 1 wherein the excitation means includes: (a) digital memory means for storing digital data in sequential locations which can be selectively read out, a magnitude of the digital data stored corresponding to the time domain waveform which is the selectively weighted and shifted inverse Fourier transform of the selected frequency domain excitation spectrum; (b) digital-to-analog converter means connected to receive digital data input from the digital memory means and connected for providing its output analog signal to the ion cell; (c) means for selectively controlling the output of the digital data stored in the digital memory means to the digital-to-analog converter means to control the application of the time domain waveform in the digital memory means in analog form to the ion cell.
Claim 9
Dependent Claim
69 words
The apparatus of claim 7 wherein the magnitude of the digital data stored in the digital memory means corresponds to a time domain waveform which is the inverse Fourier transform of the selected frequency domain excitation spectrum with, superimposed thereon, a magnitude envelope which varies as a function of time from zero magnitude at the beginning and end of the time domain waveform to a maximum magnitude level therebetween.
Claim 10
Dependent Claim
105 words
The apparatus of claim 1 wherein the means for detecting includes an amplifier means, having its input connected to a plate of the ion cell serving as a detector plate, for providing an output signal which is an amplified output of an electrical signal at the detector plate; and further including: analog-to-digital converter means, connected to the output of the amplifier means, for converting the output signal thereof from an analog to a digital data signal; means connected to receive the analog-to-digital converter means digital data output for providing output data indicative of the Fourier transform of the data signal from the analog-to-digital converter means.
Claim 11
Dependent Claim
74 words
The apparatus of claim 1 wherein the excitation means produces an electric field which has a time domain waveform which is the inverse Fourier transform of the selected frequency domain excitation spectrum with, superimposed thereon, a weighting function magnitude envelope which varies from a zero magntiude level at the beginning of the time domain waveform up to a maximum level decreases to a zero magnitude level at the end of the time domain waveform.
Claim 12
Dependent Claim
30 words
The apparatus of claim 3 wherein the derivative of the phase function with respect to the frequencies of the discrete frequency components does not exceed in absolute value π radius.
Claim 13
Independent Claim
154 words
A method of providing ion excitation to an ion cell, comprising the steps of: (a) creating a desired frequency domain spectrum which corresponds to selected mass-to-charge ratios of a range or ranges of ions to be detected and range or ranges of ions to be excluded from detection; (b) selecting discrete frequency components of the frequency domain spectrum and applying to each such component a phase such that the phase of each of the selected components varies as a non-constant function of frequencies of the components such that the frequency components are not all in phase at any point in time; (c) inverse Fourier transforming the selected frequency components to provide data indicative of a time domain waveform corresponding to a selectively weighted and shifted inverse Fourier transform; (d) applying an electric field to the ion cell which has a time domain waveform which corresponds to the data indicative of the time domain waveform.
Claim 14
Independent Claim
154 words
A method of providing ion excitation to an ion cell, comprising the steps of: (a) creating a desired frequency domain spectrum which corresponds to selected mass-to-charge ratios of a range or ranges of ions to be detected and range or ranges of ions to be excluded from detection; (b) selecting discrete frequency components of the frequency domain spectrum and applying to each such component a phase such that the phase of each of the selected components varies as a non-constant function of frequencies of the components such that the frequency components are not all in phase at any point in time; (c) inverse Fourier transforming the selected frequency components to provide data indicative of a time domain waveform corresponding to a selectively weighted and shifted inverse Fourier transform; (d) applying an electric field to the ion cell which has a time domain waveform which corresponds to the data indicative of the time domain waveform.
Claim 15
Dependent Claim
19 words
The method of claim 12 in which the phase of the frequency components varies as a non-linear, continuous function.
Claim 16
Dependent Claim
17 words
The method of claim 13 wherein the phase of the frequency components varies as a quadratic function.
Claim 17
Dependent Claim
26 words
The method of claim 12 in which the phase of the discrete frequency components varies as a nonlinear function of frequency having at least one discontinuity.
Claim 18
Dependent Claim
91 words
The method of claim 12 including, after the step of inverse Fourier transforming to provide data indicative of a time domain waveform, the additional step of applying a weighting function magnitude envelope to the data indicative of the time domain waveform which increases from a zero magnitude level at the beginning of the time domain waveform up to a maximum level a selected period of time later, remains at the maximum level over an intervening interval, and decreases to a zero magnitude level at the end of the time domain waveform.
Claim 19
Dependent Claim
93 words
The method of claim 12 including, after the step of inverse Fourier transforming the selected frequency components, the additional steps of converting the data indicative of the time domain waveform to an analog time domain signal and mixing a first higher frequency carrier signal with the analog time domain signal to provide a heterodyne signal, and wherein in the step of applying an electric field, the electric field applied has a time domain waveform which corresponds to the heterodyne signal comprising the mixed time domain signal and the first higher carrier frequency signal.
Claim 20
Dependent Claim
25 words
The method of claim 12 including the additional step of detecting cyclotron resonance motion of ions in the cell and providing a signal indicative thereof.
Claim 21
Dependent Claim
66 words
The method of claim 17 including the additional steps of detecting cyclotron resonance motion of ions in the cell and providing a signal indicative thereof, mixing the signal indicative of the ion cyclotron resonance motion with a second higher frequency carrier signal to produce a mixed signal having sum and difference frequency components, and isolating the difference frequency components indicative of the ion cyclotron resonance response.
Claim 22
Dependent Claim
80 words
The method of claim 12 wherein in the step of applying an electric field to the ion cell, the electric field has a time domain waveform which is the inverse Fourier transform of the selected frequency domain excitation spectrum with, superimposed thereon, a magnitude envelope which varies from a zero magnitude level at the beginning of the time domain waveform up to a maximum level and decreases to a zero magnitude level at the end of the time domain waveform.
Claim 23
Dependent Claim
30 words
The method of claim 14 wherein the derivative of the phase function with respect to the frequencies of the discrete frequency components does not exceed in absolute value π radians.
Claim 24
Dependent Claim
279 words
In an ion cyclotron resonance mass spectrometer of the type having an ion cyclotron resonance cell including excitation plates and detection plates, a magnet producing a substantially constant unidirectional magnetic field through the ion cyclotron resonance cell such that the electric field from potentials applied to the excitation plates is transverse to the applied magnetic field, means connected to the detector plates of the cell for detecting resonance motion of ions in the cell and providing a signal indicative thereof, and excitation amplifier means connected to the excitation plates for applying electrical potentials to the plates to form an electric field between the plates in accordance with an input signal to the excitation amplifier means, the improvement comprising: (a) digital memory means containing digital data stored in sequential locations, a magnitude of the digital data stored corresponding to a time domain waveform which is a selectively weighted and shifted inverse Fourier transform of components at discrete frequencies of a selected frequency domain excitation spectrum, wherein the phases of the discrete frequency components are varied by the excitation means as a non-constant function of the frequencies of the components such that the frequency components are not all in phase at any point in time; (b) digital-to-analog converter means connected to receive digital data input from the digital memory and connected for providing its output analog signal corresponding to the digital data to the excitation amplifier means; and (c) means for selectively controlling the output of the data stored in the digital memroy means to the digital-to-analog converter means to control the application of the time domain waveform in the digital memory means in analog form to the excitation amplifier means.
Claim 25
Dependent Claim
279 words
In an ion cyclotron resonance mass spectrometer of the type having an ion cyclotron resonance cell including excitation plates and detection plates, a magnet producing a substantially constant unidirectional magnetic field through the ion cyclotron resonance cell such that the electric field from potentials applied to the excitation plates is transverse to the applied magnetic field, means connected to the detector plates of the cell for detecting resonance motion of ions in the cell and providing a signal indicative thereof, and excitation amplifier means connected to the excitation plates for applying electrical potentials to the plates to form an electric field between the plates in accordance with an input signal to the excitation amplifier means, the improvement comprising: (a) digital memory means containing digital data stored in sequential locations, a magnitude of the digital data stored corresponding to a time domain waveform which is a selectively weighted and shifted inverse Fourier transform of components at discrete frequencies of a selected frequency domain excitation spectrum, wherein the phases of the discrete frequency components are varied by the excitation means as a non-constant function of the frequencies of the components such that the frequency components are not all in phase at any point in time; (b) digital-to-analog converter means connected to receive digital data input from the digital memory and connected for providing its output analog signal corresponding to the digital data to the excitation amplifier means; and (c) means for selectively controlling the output of the data stored in the digital memroy means to the digital-to-analog converter means to control the application of the time domain waveform in the digital memory means in analog form to the excitation amplifier means.
Claim 26
Dependent Claim
25 words
The apparatus of claim 22 in which the phases of the discrete frequency components are varied by the excitation means as a non-linear, continuous function.
Claim 27
Dependent Claim
23 words
The apparatus of claim 23 wherein the phases of the discrete frequency components are varied by the excitation means as a quadratic function.
Claim 28
Dependent Claim
30 words
The apparatus of claim 2 wherein the phases of the disccrete frequency components are varied by the excitation means as a nonlinear function of frequency having at least one discontinuity.
Claim 29
Dependent Claim
38 words
The apparatus of claim 22 including means for mixing a first higher frequency carrier signal with the time domain signal output from the digital-to-analog converter means and wherein the mixed signal is provided to the excitation amplifier means.
Claim 30
Dependent Claim
54 words
The apparatus of claim 26 including means for mixing the signal indicative of an ion resonance motion with a second carrier frequency signal to produce a mixed signal having sum and difference frequency components and including means for filtering the mixed signal to isolate the difference frequency components indicative of an ion resonance response.
Claim 31
Dependent Claim
104 words
The apparatus of claim 22 wherein the means for detecting includes an amplifier means, having an input connected to a detector plate of the ion cyclotron resonance cell, for providing an output signal which is an amplified output of the electrical signal at the detector plate, and further including: analog-to-digital converter means, connected to the output of the amplifier means, for converting the output signal thereof from an analog to a digital data signal; means connected to receive the analog-to-digital converters means digital data output for providing output data indicative of the Fourier transform of the digital data signal from the analog-to-digital converter means.
Claim 32
Dependent Claim
70 words
The apparatus of claim 22 wherein the memory means has stored therein a time domain waveform which is the inverse Fourier transform of the selected frequency domain excitation spectrum with, superimposed thereon, a magnitude envelope which varies from a zero magnitude level at the beginning of the time domain waveform up to a maximum level and decreases to a zero magnitude level at the end of the time domain waveform.
Claim 33
Dependent Claim
30 words
The apparatus of claim 22 wherein the derivative of the phase function with respect to the frequencies of the discrete frequency components does not exceed in absolute value π radians.
Claim 34
Dependent Claim
123 words
In an ion trap cell of the type having a ring electrode and end plate electrodes, an ionizing source, and a means for detecting ions ejected from the cell to produce a signal indicative thereof, the improvement comprising: excitation means connected to the end plates of the cell for producing an electric field in the cell which has a time domain waveform which is the selectively weighted and shifted inverse Fourier transform of components at disorete frequencies of a selected frequency domain excitation spectrum wherein the phases of the discrete frequency components are varied by the excitation means as a non-constant function of the frequencies of the components such that the frequency components are not all in phase in any point in time.
Claim 35
Dependent Claim
123 words
In an ion trap cell of the type having a ring electrode and end plate electrodes, an ionizing source, and a means for detecting ions ejected from the cell to produce a signal indicative thereof, the improvement comprising: excitation means connected to the end plates of the cell for producing an electric field in the cell which has a time domain waveform which is the selectively weighted and shifted inverse Fourier transform of components at disorete frequencies of a selected frequency domain excitation spectrum wherein the phases of the discrete frequency components are varied by the excitation means as a non-constant function of the frequencies of the components such that the frequency components are not all in phase in any point in time.
Claim 36
Dependent Claim
24 words
The apparatus of claim 31 wherein the phases of the discrete frequency components are varied by the excitation means as a non-linear, continuous function.
Claim 37
Dependent Claim
23 words
The apparatus of claim 32 wherein the phases of the discrete frequency components are varied by the excitation means as a quadratic function.
Claim 38
Dependent Claim
30 words
The apparatus of claim 33 wherein the phases of the discrete frequency components are varied by the exictation means as a nonlinear function of frequency having at least one discontinuity.
Claim 39
Dependent Claim
69 words
The apparatus of claim 31 wherein the excitation means includes means for mixing a first higher frequency carrier signal with a time domain signal which is the selectively weighted and shifted inverse Fourier transform of the selected frequency domain excitation spectrum and wherein the excitation means produces an electric field in the cell which varies in accordance with the first carrier frequency signal modulated by the time domain signal.
Claim 40
Dependent Claim
55 words
The apparatus of claim 35 including means for mixing the signal indicative of ions ejected from the cell with a second carrier frequency signal to produce a mixed signal having sum and difference frequency components and including means for filtering the mixed signals to isolate the difference frequency components indicative of an ion ejection response.
Claim 41
Dependent Claim
137 words
The apparatus of claim 31 wherein the excitation means includes: (a) digital memory means for storing digital data in sequential locations which can be selectively read out, a magnitude of the digital data stored corresponding to the time domain waveform which is the selectively weighted and shifted inverse Fourier transform of the selected frequency domain excitation spectrum; (b) digital-to-analog converter means connected to receive digital data input from the digital memory means and connected for providing its output analog signal corresponding to the digital data to the end plates of the ion trap cell; (c) means for selectively controlling the output of the digital data stored in the digital memory means to the digital-to-analog converter means to control the application of the time domain waveform in the digital memory in analog form to the ion trap cell.
Claim 42
Independent Claim
181 words
A method of ejecting selected mass-to-charge ratio ions from an ion trap cell of the type having a ring electrode and end plates, comprising the steps of: (a) creating a desired frequency domain spectrum which corresponds to selected mass-to-charge ratios of a range or ranges of ions to be ejected and range or ranges of ions to be held within the cell; (b) selecting discrete frequency components of the frequency domain spectrum and applying to each such component a phase such that the phase of each of the selected components varies as a non-constant function of frequencies of the components such that the frequency components are not all in phase at any point in time; (c) inverse Fourier transforming the selected frequency components to provide data indicative of a time domain waveform corresponding to the selectively weighted and shifted inverse Fourier transform; (d) applying a voltage to the end plates of the ion trap to create an electric field in the ion trap cell which has a time domain waveform which corresponds to the data indicative of the time domain waveform.
Claim 43
Independent Claim
181 words
A method of ejecting selected mass-to-charge ratio ions from an ion trap cell of the type having a ring electrode and end plates, comprising the steps of: (a) creating a desired frequency domain spectrum which corresponds to selected mass-to-charge ratios of a range or ranges of ions to be ejected and range or ranges of ions to be held within the cell; (b) selecting discrete frequency components of the frequency domain spectrum and applying to each such component a phase such that the phase of each of the selected components varies as a non-constant function of frequencies of the components such that the frequency components are not all in phase at any point in time; (c) inverse Fourier transforming the selected frequency components to provide data indicative of a time domain waveform corresponding to the selectively weighted and shifted inverse Fourier transform; (d) applying a voltage to the end plates of the ion trap to create an electric field in the ion trap cell which has a time domain waveform which corresponds to the data indicative of the time domain waveform.
Claim 44
Dependent Claim
19 words
The method of claim 38 in which the phase of the frequency components varies as a non-linear, continuous function.
Claim 45
Dependent Claim
17 words
The method of claim 39 wherein the phase of the frequency components varies as a quadratic function.
Claim 46
Dependent Claim
25 words
The method of claim 38 wherein the phase of the discrete frequency components varies as a nonlinear function of frequency having at least one discontinuity.
Claim 47
Independent Claim
207 words
A method of obtaining mass spectra from an ion cyclotron resonance mass spectrometer having enhanced dynamic range, comprising the steps of: (a) applying broadband excitation to an ion cyclotron resonance cell to acquire an ion cyclotron resonance spectrum; (b) creating a desired frequency domain spectrum having excitation bands at selected mass-to-charge ratios corresponding to selected large peaks in the previously acquired spectrum; (c) selecting discrete frequency components of the frequency domain spectrum and applying to each such component a phase such that the phase of each of the selected components varies as a non-constant function of frequencies of the components such that the frequency components are not all in phase at any point in time; (d) inverse Fourier transforming the selected frequency components to provide data indicative of a time domain waveform corresponding to the selectively weighted and shifted inverse Fourier transform; (e) applying an electric field to the ion cell which has a time domain waveform which corresponds to the data indicative of the time domain waveform at a power level to eject ions in the excitation bands; and (f) applying a broadband excitation to the ion cell to acquire an ion cyclotron resonance spectrum containing the peaks corresponding to the ions remaining in the cell.
Claim 48
Independent Claim
207 words
A method of obtaining mass spectra from an ion cyclotron resonance mass spectrometer having enhanced dynamic range, comprising the steps of: (a) applying broadband excitation to an ion cyclotron resonance cell to acquire an ion cyclotron resonance spectrum; (b) creating a desired frequency domain spectrum having excitation bands at selected mass-to-charge ratios corresponding to selected large peaks in the previously acquired spectrum; (c) selecting discrete frequency components of the frequency domain spectrum and applying to each such component a phase such that the phase of each of the selected components varies as a non-constant function of frequencies of the components such that the frequency components are not all in phase at any point in time; (d) inverse Fourier transforming the selected frequency components to provide data indicative of a time domain waveform corresponding to the selectively weighted and shifted inverse Fourier transform; (e) applying an electric field to the ion cell which has a time domain waveform which corresponds to the data indicative of the time domain waveform at a power level to eject ions in the excitation bands; and (f) applying a broadband excitation to the ion cell to acquire an ion cyclotron resonance spectrum containing the peaks corresponding to the ions remaining in the cell.
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