@article {2333,
	title = {Dipole excitation of ions in linear radio frequency quadrupole ion traps with added multipole fields},
	journal = {International Journal of Mass Spectrometry},
	volume = {275},
	number = {1-3},
	year = {2008},
	note = {ISI Document Delivery No.: 338OVTimes Cited: 1Cited Reference Count: 35Zhao, XianZhen Douglas, D. J.},
	month = {Aug},
	pages = {91-103},
	type = {Article},
	abstract = {Ion motion with auxiliary dipole excitation and collisional damping in a linear radiofrequency quadrupole ion trap incorporating small amounts of even higher order multipoles is studied analytically. The ion motion is modeled in a pseudopotential that is mostly quadratic with small amounts of higher spatial harmonics. Ion motion along x and y axes is characterized by two uncoupled forced and damped anharmonic oscillator equations. A multiple time scales method is used to solve the equations of motion of ions with a first order perturbation Correction. Analytical relations between the oscillation amplitudes at steady state (the stationary amplitudes) and excitation frequency are calculated. The frequency response Curves show that in some cases bistable behavior might be obtained, i.e., there are two stable stationary amplitudes for a given excitation frequency. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.},
	keywords = {BOUNDARY, higher order multipole, ion excitation, linear ion trap, MASS-SPECTROMETER, MOTION, nonlinear, OCTOPOLE FIELD, PAUL TRAPS, RESONANCE, RESONANCE EJECTION, SCAN, SIMULATION},
	isbn = {1387-3806},
	url = {<Go to ISI>://000258518200011},
	author = {Zhao, X. Z. and Douglas, D. J.}
}
@article {1200,
	title = {Ion excitation in a linear quadrupole ion trap with an added octopole field},
	journal = {Journal of the American Society for Mass Spectrometry},
	volume = {16},
	number = {6},
	year = {2005},
	note = {ISI Document Delivery No.: 928AZTimes Cited: 17Cited Reference Count: 32},
	month = {Jun},
	pages = {835-849},
	type = {Article},
	abstract = {Modeling of ion motion and experimental investigations of ion excitation in a linear quadrupole trap with a 4 \% added octopole field are described. The results are compared with those obtained with a conventional round rod set. Motion in the effective potential of the rod set can explain many of the observed phenomena. The frequencies of ion oscillation in the x and y directions shift with amplitude in opposite directions as the amplitudes of oscillation increase. Excitation profiles for ion fragmentation become asymmetric and in some cases show bistable behavior where the amplitude of oscillation suddenly jumps between high and low values with very small changes in excitation frequency. Experiments show these effects. Ions are injected into a linear trap, stored, isolated, excited for MS/MS, and then mass analyzed in a time-of-flight mass analyzer. Frequency shifts between the x and y motions are observed, and in some cases asymmetric excitation profiles and bistable behavior are observed. Higher MS/MS efficiencies are expected when an octopole field is added. MS/MS efficiencies ((2) collision gas) have been measured for a conventional quadrupole rod set and a linear ion trap with a 4 \% added octopole field. Efficiencies are chemical compound dependent, but when an octopole field is added, efficiencies can be substantially higher than with a conventional rod set, particularly at pressures of 1.4 X 10(-4) torr or less. (c) 2005 American Society for Mass Spectrometry.},
	keywords = {EJECTION, MASS-SPECTROMETER, OF-FLIGHT SYSTEM, PAUL TRAP, RESONANT EXCITATION, SCAN, SIMULATION},
	isbn = {1044-0305},
	url = {<Go to ISI>://000229244800004},
	author = {Michaud, A. L. and Frank, A. J. and Ding, C. and Zhao, X. Z. and Douglas, D. J.}
}
@article {747,
	title = {Linear quadrupoles with added octopole fields},
	journal = {Rapid Communications in Mass Spectrometry},
	volume = {17},
	number = {20},
	year = {2003},
	note = {ISI Document Delivery No.: 731CTTimes Cited: 21Cited Reference Count: 29},
	pages = {2290-2294},
	type = {Article},
	abstract = {Two methods of adding relatively small octopole fields to the main quadrupole field of quadrupoles and linear ion traps with cylindrical rods are investigated. The first, {\textquoteright}stretching{\textquoteright} the quadrupole by moving two rods out from the axis, produces a combination of higher order fields with similar magnitudes in which the octopole field is not necessarily the greatest. The quadrupole field strength is changed significantly and a large potential appears on the axis. The second method uses rod pairs of different diameters. It adds octopole components of up to several percent while all other higher order fields remain small. An axis potential is also added, but it is only a few percent of the radio-frequency (RF) voltage and approximately equal to the strength of the octopole field. The axis potential can be removed by moving the larger rod pair out from the axis or applying unbalanced RIF to the electrodes. Copyright (C) 2003 John Wiley Sons, Ltd.},
	keywords = {EJECTION, FILTER, HARMONICS, MASS-SPECTROMETER, NONLINEAR ION-TRAP, OF-FLIGHT SYSTEM, RESONANCE, SPATIAL, STORAGE-RING},
	isbn = {0951-4198},
	url = {<Go to ISI>://000185867500008},
	author = {Sudakov, M. and Douglas, D. J.}
}
@article {3846,
	title = {Characteristics of an inductively coupled argon plasma operating with organic aerosols .4. Noise power spectra},
	journal = {Journal of Analytical Atomic Spectrometry},
	volume = {11},
	number = {11},
	year = {1996},
	note = {ISI Document Delivery No.: VT965Times Cited: 3Cited Reference Count: 31},
	month = {Nov},
	pages = {1011-1018},
	type = {Article},
	abstract = {With the use of noise power spectra it is shown that the vortex shedding frequency depends on the solvent and the solvent plasma load, and modulates both the plasma boundary and analyte plume of the discharge.},
	keywords = {ATOMIC EMISSION-SPECTROMETRY, DROPLETS, FLOW TORCH, fluctuations, INDUCTIVELY COUPLED ARGON PLASMA, jet, LOAD, MASS-SPECTROMETER, noise power spectra, ORGANIC SOLVENT, SOLVENT, SOLVENT PLASMA LOAD},
	isbn = {0267-9477},
	url = {<Go to ISI>://A1996VT96500002},
	author = {Weir, D. G. and Blades, M. W.}
}
