Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J49/00—Particle spectrometers or separator tubes
  • H01J49/26—Mass spectrometers or separator tubes
  • H01J49/34—Dynamic spectrometers
  • H01J49/42—Stability-of-path spectrometers, e.g. monopole, quadrupole, multipole, farvitrons
  • H01J49/426—Methods for controlling ions
  • H01J49/427—Ejection and selection methods
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J49/00—Particle spectrometers or separator tubes
  • H01J49/02—Details
  • H01J49/022—Circuit arrangements, e.g. for generating deviation currents or voltages ; Components associated with high voltage supply
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J49/00—Particle spectrometers or separator tubes
  • H01J49/26—Mass spectrometers or separator tubes
  • H01J49/34—Dynamic spectrometers
  • H01J49/42—Stability-of-path spectrometers, e.g. monopole, quadrupole, multipole, farvitrons
  • H01J49/426—Methods for controlling ions
  • H01J49/4295—Storage methods

Definitions

• This invention relates to quadrupole mass spectrometry.
• the invention relates to quadrupole mass spectrometry.
• the invention relates to quadrupole mass spectrometry.
• quadrupole ion trap device such as a linear quadrupole ion trap device
• the invention also relates to
• structure includes a pair of x-electrodes 1 , a pair of y-electrodes 2, an ion entrance plate
• Both plates 3,4 can be used to set a potential barrier to prevent
• the quadrupole ion trap structure includes a
• Patent No. 2,939,952 teaches a method of generating a sinusoidal high frequency voltage
• RF voltage is usually referred to as a radio frequency (RF) voltage.
• a RF power supply comprises a driving electric circuit and a resonating
• the RF voltage being proportion to mass-to-charge ratio when the RF frequency is fixed.
• rectangular wave d ⁇ ving is associated with digital frequency scanning and timing
• the method of this invention utilizes a time-varying rectangular wave voltage applied to
• a quadrupole ion trap device for ion trapping, selection, and/or mass analyzing
• quadrupole ion trap device including creating a digital signal, using the digital signal to
• a quadrupole ion trap device means for creating a digital signal, a set of switches
• the said quadrupole ion trap device may be an ion trapping system in a form of linear
• ion trap structure that can be used to generate a quadruople electric field for storing and/or
• Figure l a shows a known linear form of quadrupole ion trap structure
• Figure lb shows a known 3-D rotationally-symmetric quadruople ion trapping structure
• FIG. 2 shows a time-varying rectangular wave voltage in accordance with the invention
• Figure 3a is a block schematic diagram showing one embodiment of a drive apparatus
• Figure 3b is a block schematic diagram showing another embodiment of a drive apparatus
• Figure 4 shows the characteristics of ion motion in a quadrupole ion trap driven by
• Figure 5 illustrates the stable region (shown hatched) in a plot of a against q for ion
• the rectangular wave voltage shown in Figure 2 has a width w, at a high voltage level V,
• Figure 3a shows an example of a drive apparatus for generating the rectangular wave
• the drive apparatus includes a clock 1 1 for generating a high
• a count unit 13 has a number of counters and
• a mass scan control unit 14 which sets the
• the digital signal 15 having the required pulse pattern is then supplied to a switch circuit
• Switches 16 and 17 are typically bipolar or FET
• An adaption circuit between the count unit 13 and the switches 16,17 may be
• Switch 16 is connected to a low level DC
• control signal 15 the high and low level voltages V,,V 2 which form the rectangular wave
• Figure 3b shows yet another example of driving apparatus for generating the rectangular
• Synthesiser (DDS) 25 and fast comparator 26 to generate the digital control signal.
• DDS 25 produces a periodic waveform of a certain frequency preset by the mass control
• digital signal 15 is precisely generated and then used to control the switch circuit in the manner already described.
• the dipole excitation voltage may have a range of
• AC waveforms such as harmonic sinusoidal waveform, a broad-band multi
• the excitation voltage source may be also in the form of switch
• circuits which are controlled by digital signals which have a predetermined relationship
• the DC power supply 19 may be set at a voltage having the
• the resultant DC voltage offset can be cancelled out by applying a DC bias voltage
• each of another pair of diagonally opposed electrodes is driven by a similar switch circuit
• C,D,G,H can be derived from the condition at the start of the half cycle
• the trajectory of an ion can be calculated by alternatively using the two phase space
• ions can be separated into ions undergoing stable motion and ions
• GB 1346393 and a paper by the same inventor have disclosed the method of choosing band-width of the stability region by varying the duty cycle of the rectangular wave and
• This frequency will be referred to as the intrinsic frequency of the ion motion.
• excitation AC voltage can be a single frequency, sinusoidal voltage or a rectangular wave
• excitation frequency ⁇ () e.g. from 0 to ⁇ f.
• f can be varied by increasing or decreasing the values of N w l and N w2 if the digital counting method is used to generate the digital control signal
• the switching circuitry used to generate the rectangular wave voltage will have limited
• a broad band waveform generator In the case of broad band excitation, a broad band waveform generator can still be used
• the rectangular wave voltage driven quadrupole mass spectrometry has the
• the rectangular wave voltage may be generated using a switching circuit which does not
• a practical range may be from 10kHz to 10MHz. It is known from the
• scanning is made wider by varying frequency than by varying voltage within certain
• a rectangular waveform can be defined using more parameters than is the case for a
• sinusoidal wavefo ⁇ n e.g. amplitude, repetition rate, number of transitions within each
• the rectangular waveform pattern can easily be changed
• a switching circuit used to generate a rectangular wave voltage consumes less power than

Landscapes

• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Electron Tubes For Measurement (AREA)
• Other Investigation Or Analysis Of Materials By Electrical Means (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (2)

Family

ID=10863000

Family Applications (1)

Country Status (7)

Cited By (17)

Families Citing this family (29)

Family Cites Families (21)

• 1999
  • 1999-10-19 GB GBGB9924722.3A patent/GB9924722D0/en not_active Ceased
• 2000
  • 2000-10-16 EP EP00968112A patent/EP1222680B1/en not_active Expired - Lifetime
  • 2000-10-16 JP JP2001531124A patent/JP4668496B2/ja not_active Expired - Fee Related
  • 2000-10-16 RU RU2002113091/28A patent/RU2249275C2/ru not_active IP Right Cessation
  • 2000-10-16 WO PCT/GB2000/003964 patent/WO2001029875A2/en not_active Ceased
  • 2000-10-16 US US10/089,963 patent/US7193207B1/en not_active Expired - Lifetime
  • 2000-10-16 DE DE60043067T patent/DE60043067D1/de not_active Expired - Lifetime

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