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Influence of the 6th and 10th spatial harmonics on the peak shape of a quadrupole mass filter with round rods
Author(s) -
Douglas D. J.,
Konenkov N. V.
Publication year - 2002
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.735
Subject(s) - chemistry , rod , radius , quadrupole , sign (mathematics) , term (time) , harmonics , resolution (logic) , ion , spherical harmonics , field (mathematics) , atomic physics , filter (signal processing) , aspect ratio (aeronautics) , analytical chemistry (journal) , molecular physics , mathematical analysis , physics , mathematics , quantum mechanics , chromatography , medicine , alternative medicine , computer security , pathology , voltage , artificial intelligence , computer science , pure mathematics , organic chemistry , optoelectronics , computer vision
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, $\phi _N,\Phi (x, y) = \sum_{N = 0}^{\infty} A_N \phi_N/r_{0}^{N}$ , 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 ≈ 1.13. With this ratio the dodecapole term ( A 6 ) is ca. 1 × 10 −3 , but its effects are partially compensated by the A 10 term which has similar magnitude, but opposite sign. Copyright © 2002 John Wiley & Sons, Ltd.