Modulation parametric resonances and their influence on stability diagram structure

Sheretov, Ernst P.; Gurov, Victor S.; Kolotilin, B. I.

doi:10.1016/s1387-3806(99)00013-5

Cited by 10 publications

(10 citation statements)

References 5 publications

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“…As a result, the original stability region splits into islands of stability. Amplitude modulation of the main trapping voltage also produces instability bands on the stability diagram [4,8].In this paper we describe a study of the upper stable island caused by modulation of the RF or DC and RF voltages by a small auxiliary signal. The location of the stability islands for different values of the amplitude of modulation and the ratio ϭ /⍀ are given in detail.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

“…The theory of ion excitation is well-developed and has been applied to the problem of 3D ion trap tandem mass spectrometry [2,3]. The modulation of the quadrupole mass filter (QMF) voltage, U-Vcos⍀t, by a small auxiliary RF signal for resonant excitation of the ion oscillations is discussed in [4]. Data were obtained for the most general case of a periodic trapping voltage, for the 3D ion trap, and for the linear mass filter.…”

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confidence: 99%

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Upper stability island of the quadrupole mass filter with amplitude modulation of the applied voltages

Konenkov

Korol'kov

Machmudov

2005

J. Am. Soc. Mass Spectrom.

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Modulation of the voltages applied to a quadrupole mass filter (QMF), either RF or RF and DC, leads to splitting of the stability region into islands of stability. The ion optical properties, such as transmission, resolving power and peak tails of the first upper stability islands have been investigated by numerical simulation of ion trajectories. The dependence of the location of this island on the amplitude of the modulation and the parameter ϭ /⍀ ϭ Q/P where is modulation frequency, ⍀ is main angular radio frequency, and Q and P are integers, is calculated in detail. Different methods of adjusting the QMF resolution are examined. It is found that operation at the upper and lower tips of the stability islands created by amplitude modulation of the RF voltage is preferred, because of the technical simplicity of this method and a reduction of the required separation time. Amplitude modulation of the RF and DC potentials applied to a quadrupole is an example of parametric excitation. The theory of parametric resonance of different orders of the ion oscillations in quadrupole RF fields is given in [5] and investigated experimentally in [6]. Mass separation in upper stable island was used previously to modify and improve the peak shape [7]. The general problem of the calculation of stability diagrams for ion motion in periodic RF quadrupole fields is reviewed in [8]. The resonant excitation of the ion oscillations by a weak auxiliary RF signal produces strong changes in the Mathieu stability diagram [5][6][7][8][9][10]. The excitation causes instability bands, along the iso-␤ lines. As a result, the original stability region splits into islands of stability. Amplitude modulation of the main trapping voltage also produces instability bands on the stability diagram [4,8].In this paper we describe a study of the upper stable island caused by modulation of the RF or DC and RF voltages by a small auxiliary signal. The location of the stability islands for different values of the amplitude of modulation and the ratio ϭ /⍀ are given in detail. Different methods of adjusting the resolution are examined. We show that operation at the upper and lower tips of the islands created by amplitude modulation of the RF voltage is preferred because of the technical simplicity and a reduction of the required separation time. We show that a rod set that is constructed with round rods and operated with modulation of the voltages can give higher performance than an ideal quadrupole field without modulation.

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confidence: 99%

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confidence: 99%

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confidence: 99%

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Upper stability island of the quadrupole mass filter with amplitude modulation of the applied voltages

Konenkov

Korol'kov

Machmudov

2005

J. Am. Soc. Mass Spectrom.

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“…Methods other than quadrupole excitation such as modulation of the RF amplitude [27] can produce similar results. With amplitude modulation at frequency , the equation of ion motion is…”

Section: Stability Diagram With Amplitude Modulation Of the Trapping mentioning

confidence: 89%

“…Although the details of Figure 12a and b are a bit different, the qualitative structure of the diagrams is the same. Previous theoretical approaches to quadrupole excitation in quadrupole fields [6c, 21,27] were based on perturbation theory for small values of a and q. The perturbation result is valid if the parameter Q is small.…”

Section: Rf-only Quadrupole With Auxiliary Quadrupole Excitationmentioning

confidence: 99%

Matrix methods for the calculation of stability diagrams in quadrupole mass spectrometry

Konenkov

Sudakov

Douglas

2002

J. Am. Soc. Mass Spectrom.

112

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The theory of the computer calculation of the stability of ion motion in periodic quadrupole fields is considered. A matrix approach for the numerical solution of the Hill equation and examples of calculations of stability diagrams are described. The advantage of this method is that it can be used for any periodic waveform. The stability diagrams with periodic rectangular waveform voltages are calculated with this approach. Calculations of the conventional stability diagram of the 3-D ion trap and the first six regions of stability of a mass filter with this method are presented. The stability of the ion motion for the case of a trapping voltage with two or more frequencies is also discussed. It is shown that quadrupole excitation with the rational angular frequency ϭ N⍀/P (where N, P are integers and ⍀ is the angular frequency of the trapping field) leads to splitting of the stability diagram along iso-␤ lines. Each stable region of the unperturbed diagram splits into P stable bands. The widths of the unstable resonance lines depend on the amplitude of the auxiliary voltage and the frequency. With a low auxiliary frequency splitting of the stability diagram is greater near the boundaries of the unperturbed diagram. It is also shown that amplitude modulation of the trapping RF voltage by an auxiliary signal is equivalent to quadrupole excitation with three frequencies. The effect of modulation by a rational frequency is similar to the case of quadrupole excitation, although splitting of the stability diagram differs to some extent. The methods and results of these calculations will be useful for studies of higher stability regions, resonant excitation, and non-sinusoidal trapping voltages. (J Am Soc Mass Spectrom 2002, 13, 597-613)

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Linear quadrupoles in mass spectrometry

Douglas

2009

Mass Spectrometry Reviews

125

111

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The use of linear quadrupoles in mass spectrometry as mass filters and ion guides is reviewed. Following a tutorial review of the principles of mass filter operation, methods of mass analysis are reviewed. Discussed are extensions of quadrupole mass filters to higher masses, scanning with frequency sweeps of the quadrupole waveform, operation in higher stability regions, and operation with rectangular or other periodic waveforms. Two relatively new methods of mass analysis the use of "islands of stability" and "mass selective axial ejection" are then reviewed. The optimal electrode geometry for a quadrupole mass filter constructed with round rods is discussed. The use of collisional cooling in quadrupole ion guides is discussed along with ion guides that have axial fields. Finally, mass analysis with quadrupoles that have large distortions to the geometry and fields is discussed. An Appendix gives a brief tutorial review of definitions of electrical potentials and fields, as well as the units used in this article.

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Modulation parametric resonances and their influence on stability diagram structure

Cited by 10 publications

References 5 publications

Upper stability island of the quadrupole mass filter with amplitude modulation of the applied voltages

Upper stability island of the quadrupole mass filter with amplitude modulation of the applied voltages

Matrix methods for the calculation of stability diagrams in quadrupole mass spectrometry

Linear quadrupoles in mass spectrometry

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