@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 {4222,
	title = {A new linear ion trap time-of-flight system with tandem mass spectrometry capabilities},
	journal = {Rapid Communications in Mass Spectrometry},
	volume = {12},
	number = {20},
	year = {1998},
	note = {ISI Document Delivery No.: 130DBTimes Cited: 92Cited Reference Count: 64},
	pages = {1463-1474},
	type = {Article},
	abstract = {A new hybrid linear ion trap time-of-flight mass spectrometer has been constructed and the first results for tandem-in-time MS/MS in a 2-dimensional Paul trap are presented. The instrument consists of an electrospray ionization source and two radio frequency (RF) only quadrupoles operating at a pressure of 7 mTorr N-2 which are coupled orthogonally to a linear TOFMS. Ions are trapped in an RF-only quadrupole through the application of timed stopping potentials on the entrance and exit apertures. Through the coupling of an auxiliary waveform generator on one pair of the ion trap rods a small dipolar excitation voltage is superimposed on the quadrupolar electric field. This voltage is used for precursor isolation via broadband excitation and collision induced dissociation through mass selective resonant excitation. Instrumental performance and choice of operating parameters are demonstrated by recording fragment spectra for +3 ions of renin substrate and fl ions of reserpine. TOFMS mass resolution (m/Delta m)(FWHM) is as high as 740 at m/z = 609. Fragmentation efficiency is greater than 50\% and excitation mass resolution is 60-75. (C) 1998 John Wiley \& Sons, Ltd.},
	keywords = {DECOMPOSITION, EJECTION, ELECTROSPRAY-IONIZATION, FREQUENCY STANDARD APPLICATIONS, MOLECULE REACTION, PARAMETERS, PERFORMANCE, PROTEINS, QUADRUPOLE, RESONANCE, SPECTROSCOPY},
	isbn = {0951-4198},
	url = {<Go to ISI>://000076503200007},
	author = {Campbell, J. M. and Collings, B. A. and Douglas, D. J.}
}
@article {3856,
	title = {LEED crystallographic analysis for the Rh(111)-(2x1)-O surface structure},
	journal = {Surface Science},
	volume = {360},
	number = {1-3},
	year = {1996},
	note = {ISI Document Delivery No.: UX923Times Cited: 29Cited Reference Count: 32},
	month = {Jul},
	pages = {137-143},
	type = {Article},
	abstract = {A tensor LEED analysis is reported For the Rh(111)-(2 x 1)-O surface structure in which atoms in the O overlayer chemisorb close to the regular (fcc type) three-fold hollow sites for half-monolayer coverage. The structure shows significant relaxations: for example, a buckling of about 0.07 Angstrom is indicated in the first metal layer and O appears to displace laterally by about 0.05 Angstrom. The individual O-Rh bond lengths are around 2.01 and 1.92 Angstrom to top layer Rh atoms, which bond to two and one O atoms, respectively, but the average value (1.98 Angstrom) is close to that in bulk RhO2 (1.96 Angstrom). Comparison is also made with the previously determined O-Rh bond lengths in the Rh(110)-p2mg(2 x 1) surface structure.},
	keywords = {CLOSE-PACKED SURFACE, EJECTION, ENERGY-ELECTRON-DIFFRACTION, LAYER, low energy electron diffraction, low index single crystal surfaces, OXYGEN, P(2X2)O/RH(111), RECONSTRUCTION, RELAXATIONS, RH(111), rhodium, surface relaxations, THERMAL-DESORPTION},
	isbn = {0039-6028},
	url = {<Go to ISI>://A1996UX92300022},
	author = {Wong, K. C. and Liu, W. and Mitchell, K. A. R.}
}
