Determination of analytic potentials from finite element computations

Barlow, Stephan E.; Taylor, Aimee; Swanson, Kenneth R.

doi:10.1016/s1387-3806(00)00452-8

Cited by 7 publications

(4 citation statements)

References 9 publications

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“…In this work we follow the semi‐analytical method proposed years ago by Dawson and Whetton 15. The analytical description of the potential is based on spatial harmonics, as has been widely used in many theoretical studies16–22 of the nature of nonlinear resonances17,, 18 or ion motion in an ion trap with distorted fields 16,. 19,, 20 The potentials for higher multipoles constructed with round rods have been discussed by Boerboom21 and Rama Rao et al 22…”

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confidence: 99%

Influence of the 6th and 10th spatial harmonics on the peak shape of a quadrupole mass filter with round rods

Douglas

Konenkov

2002

Rapid Comm Mass Spectrometry

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The influence of the ratio of the rod radius, r, to field radius, r(0), on the peak shape for a linear quadrupole mass filter constructed with round rods has been investigated. The expansion of the potential in multipoles, phi(N),Phi(x, y) = sum(infinity)(N=0)A(N)phi(N)/r(N)(0) has been considered, and the peak shape and resolution have been determined by numerical calculation of ion trajectories in quadrupoles with different ratios, r/r(0). Geometries that make the dodecapole term (A(6)) zero (r/r(0) = 1.14511) do not give the best performance because the contribution of the 20-pole term, A(10), must be considered. The optimum ratio is r/r(0) approximately 1.13. With this ratio the dodecapole term (A(6)) is ca. 1 x 10(-3), but its effects are partially compensated by the A(10) term which has similar magnitude, but opposite sign.

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confidence: 99%

Influence of the 6th and 10th spatial harmonics on the peak shape of a quadrupole mass filter with round rods

Douglas

Konenkov

2002

Rapid Comm Mass Spectrometry

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“…By dividing this slope by 4eqNarN2Ω2 (where q = 0.908), A 2 is found to be equal to 0.884. An alternative approach to estimate A 2 theoretically involves fitting the SIMION-obtained potentials inside the trap to a multipole expansion equation [48, 49] (see section 2 in the Supplementary materials for a detailed description of this method), and with this method we predict A 2 to be 0.866. Experimentally, A 2 is estimated to be 0.867, based on a mass instability scan obtained at room temperature.…”

Section: Resultsmentioning

confidence: 99%

Operation and Performance of a Mass-Selective Cryogenic Linear Ion Trap

Tesler

Cismesia

Bell

et al. 2018

J. Am. Soc. Mass Spectrom.

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We report on the performance of a cryogenic 2D linear ion trap (cryoLIT) that is shown to be mass-selective in the temperature range of 17-295 K. As the cryoLIT is cooled, the ejection voltages during the mass instability scan decrease, which results in an effective mass shift to lower m/z relative to room temperature. This is attributed to a decrease in trap radius caused by thermal contraction. Additionally, the cryoLIT generates reproducible mass spectra from day-to-day, and is capable of performing stored waveform inverse Fourier transform (SWIFT) mass isolation of fragile N-tagged ions for the purpose of background-free infrared dissociation spectroscopy. Graphical Abstract ᅟ.

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“…They are also complete and unique, with respect to our choice of z = 0. Sometimes the choice of the origin will not be immediately obvious, techniques for finding the point are discussed by Barlow et al, [2] but lie outside the scope of this summary. "Fable I summarizes the even order coefficients for each of these trap geometries.…”

Section: The Multipole Expansionmentioning

confidence: 99%