Resonance excitation of ions stored in a quadrupole ion trap Part II. Further simulation studies

March, Raymond E.; McMahon, Adam; Allinson, E. Tracey; Londry, Frank A.; Alfred, Roland L.; Todd, John F. J.; Vedel, Fernande

doi:10.1016/0168-1176(90)85024-v

Cited by 56 publications

(34 citation statements)

References 9 publications

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“…Previous studies by March et al [1][2][3][4][5][6] have demonstrated that signatures of resonant excitation can be readily observed in simulations of single ion trajectories inside an ion trap. A survey of early work on single ion trajectories is given by Cooks and coworkers, who have developed the NQS [7] and ITSIM [8][9][10] software packages to simulate multiple ion trajectories with the inclusion of ion-ion (space charge) and ion-neutral (buffer gas) interactions.…”

Section: Introductionmentioning

confidence: 99%

“…Helium poses as a better indicator because it is absent from metabolic pathways of microorganisms and it is chemically inert in rocks. Measuring the 3 He/ 4 He isotope ratio relative to air can indicate if helium is coming from the mantle ( 3 He) or from the fracturing crust ( 4 He) because of imminent volcanic eruption.…”

Section: He/ 4 He Ratio Measurements As An Indicator Of Volcanic Unrestmentioning

confidence: 99%

“…Continuous monitoring of 3 He/ 4 He isotope ratio in diffuse helium flux for forecasting volcanic eruptions could strengthen existing surveillance programs [35]. Standard diffuse degassing methods focus on detecting percolated CO 2 and H 2 S gas as precursors to volcanic eruptions [36].…”

Section: He/ 4 He Ratio Measurements As An Indicator Of Volcanic Unrestmentioning

confidence: 99%

“…In order to accurately measure the 3 He/ 4 He isotope ratio under low-power constraints of a portable field instrument, our main challenge is to attain the sufficient mass resolution for resolving species that constitute isobaric interferences. Since hydrogen outgassing from vacuum components is the dominant source of contamination, main interferences come from HD (for 3 He) and D 2 (for 4 He).…”

Section: He/ 4 He Ratio Measurements As An Indicator Of Volcanic Unrestmentioning

confidence: 99%

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Computer Modeling of an Ion Trap Mass Analyzer, Part I: Low Pressure Regime

Nikolić

Madzunkov

Darrach

2015

J. Am. Soc. Mass Spectrom.

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Abstract. We present the multi-particle simulation program suite Computational Ion Trap Analyzer (CITA) designed to calculate the ion trajectories within a Paul quadrupole ion trap developed by the Jet Propulsion Laboratory (JPL). CITA uses an analytical expression of the electrodynamic field, employing up to six terms in multipole expansion and a modified velocity-Verlet method to numerically calculate ion trajectories. The computer code is multithreaded and designed to run on sharedmemory architectures. CITA yields near real-time simulations with full propagation of 26 particles per second per core. As a consequence, a realistic numbers of trapped ions (100+ million) can be used and their trajectories modeled, yielding a representative prediction of mass spectrometer analysis of trace gas species. When the model is compared with experimental results conducted at low pressures using the conventional quadrupole and dipole excitation modes, there is an excellent agreement with the observed peak shapes. Owing to the program's efficiency, CITA has been used to explore regions of trapping stability that are of interest to experimental research. These results are expected to facilitate a fast and reliable modeling of ion dynamics in miniature quadrupole ion trap and improve the interpretation of observed mass spectra.

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Section: Introductionmentioning

confidence: 99%

Section: He/ 4 He Ratio Measurements As An Indicator Of Volcanic Unrestmentioning

confidence: 99%

Section: He/ 4 He Ratio Measurements As An Indicator Of Volcanic Unrestmentioning

confidence: 99%

Section: He/ 4 He Ratio Measurements As An Indicator Of Volcanic Unrestmentioning

confidence: 99%

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Computer Modeling of an Ion Trap Mass Analyzer, Part I: Low Pressure Regime

Nikolić

Madzunkov

Darrach

2015

J. Am. Soc. Mass Spectrom.

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“…To the best of our knowledge, prior studies of nonlinear fields, dipolar AC excitation induced resonances, or other resonances not due to harmonics of an ion's fundamental secular frequency ( o ) for linear quadrupoles were first investigated in 2003 [2]. Previously, extensive theoretical and simulation studies of fields and resonance effects for Paul ion traps were published in two series of articles between 1989 and 1994 [8,[21][22][23][24][25][26][27][28][29]. Two of these articles discuss dipolar resonant excitation [8,28].…”

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confidence: 99%

Study of the enhancement of dipolar resonant excitation by linear ion trap simulations

Williams

Siu

Londry³

et al. 2007

J. Am. Soc. Mass Spectrom.

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Resolution improvements in dipolar resonant excitation have been examined in a round-rod quadrupolar collision cell for values of the Mathieu characteristic exponent ␤ equal to n/p, where n and m are small integers (prime ␤ values) versus other ␤ values where n and p are not small (ordinary␤ values). The trajectories of ions moving in the time-varying electric fields of a quadrupole with and without buffer-gas molecules were calculated to determine the relationship of prime and ordinary ␤ values to frequency resolution for resonant ion excitation and ejection. For prime ␤ values, the ion trajectory in the hyperbolic quadrupole field will be exactly periodic with a period of at most 4 p/⍀, where ⍀ is the angular frequency of the main drive radio-frequency ( . By scanning the RF voltage, trapped ions may be ejected one m/z ratio at a time out of the confining electric field for detection. While the ions are confined, ion-molecule reactions may be carried out. Additionally, the kinetic energy of the trapped ions can be increased by applying a dipolar AC potential that is resonant with the secular frequency of the motion of ions ( 0 ) of one or more m/z values. This increased kinetic energy can be used to selectively eject the ions from the trapping field, or to add internal energy to the confined ions through collisions with a neutral gas added to the trap. This dipolar resonant excitation has been a common method for performing mass-selective ejection and fragmentation of ions confined in Paul traps and, more recently, in linear ion traps [2][3][4]. The theory of instability space, as it relates to auxiliary AC excitation in a linear and 3D quadrupole trap for quadrupolar resonant excitation, has been addressed [5][6][7]. The trajectories of ions in a linear ion trap with dipolar auxiliary excitation have been examined by Franzen [8]; those for hyperbolic and circular quadrupole rods with and without collision gas by Collings et al. [2].In tandem mass spectrometry (MS/MS), resolution of the product ions is sometimes crucial as many fragments have similar m/z values [9 -15]. Unambiguous product-ion assignment often requires better than unit-mass resolution to resolve "isobaric" interferences, which are particularly acute when the analyte is the minor component. Two factors that degrade m/z resolution after dipolar resonance excitation are increasing collisions with buffer-gas molecules [2] and increasing dipolar voltage amplitude [16]. One method to increase resolution is to excite the ions in such a way to reduce the frequency composition and the periodicity of the ions' motion in the electric field. In the present study, we used simulation software to determine the trajectories of ions [17] moving in a time-varying electric field and colliding with buffer-gas molecules in a linear quadrupole reaction cell with the instrumentally common and practical round-rod geometry.It is a common misconception that an ion trajectory within the quadrupolar field is necessarily aperiodic. As we will show below, provided that the...

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Simulation of External Ion Injection, Cooling and Extraction Processes with SIMION 6.0 for the Ion Trap/Reflectron Time-of-flight Mass Spectrometer

Lubman

1997

Rapid Commun. Mass Spectrom.

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In this work we have developed a PC-based simulation to study ion injection, cooling and extraction processes for multiple ions in an trap/reflectron time-of-flight (IT/reTOF) system. This simulation is based upon SIMION 6.0 with user written programs in which a 3D collision model is used to describe ion--buffer gas molecule interactions. The results of various simulations describing the relation between the trapping efficiency for external injection of ions into the trap and the RF phase, and the effects of initial kinetic energy and ramp-up rate on dynamic trapping of externally produced ions are discussed. Further, single-pulsing and bipolar-pulsing schemes for ejecting ions from the trap are examined. The simulations show that bipolar pulsing can markedly improve the resolution. In the bipolar ejection mode the relation between resolution and the extraction voltages and RF ramp-off rate are studied.

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Resonance excitation of ions stored in a quadrupole ion trap Part II. Further simulation studies

Cited by 56 publications

References 9 publications

Computer Modeling of an Ion Trap Mass Analyzer, Part I: Low Pressure Regime

Computer Modeling of an Ion Trap Mass Analyzer, Part I: Low Pressure Regime

Study of the enhancement of dipolar resonant excitation by linear ion trap simulations

Simulation of External Ion Injection, Cooling and Extraction Processes with SIMION 6.0 for the Ion Trap/Reflectron Time-of-flight Mass Spectrometer

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