Coupled gas and ion transport in quadrupole interfaces

Jugroot, Manish; Groth, C. P. T.; Thomson, Bruce A.; Baranov, Vladimir; Collings, B. A.; French, John B.

doi:10.1088/0022-3727/41/2/025205

Cited by 16 publications

(11 citation statements)

References 30 publications

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“…One plausible explanation for doubly protonated bombesin requiring higher pressure to reach a maximum intensity is that its kinetic energy was significantly higher than that of caffeine, both due to its higher mass and its being doubly charged. Immediately after the ions are transferred into the vacuum, the velocities of ions of small and large mass are expected to be similar,55 which makes the kinetic energies of the high‐mass ions higher (until thermal equilibrium, a pressure‐dependent process, is established). Additionally, in comparison with caffeine, doubly charged bombesin ions gain more kinetic energy along the ion optical axis by the DC electric field (i.e.…”

Section: Resultsmentioning

confidence: 99%

Ion trap mass analysis at high pressure: an experimental characterization

Song¹,

Xu²,

Smith³

et al. 2009

J. Mass Spectrom.

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In recent years, it has become increasingly interesting to understand the performance of mass spectrometers at pressures much higher than those employed with conventional operating conditions. This interest has been driven by several influences, including demand for the development of reduced-power miniature mass spectrometers, desire for improved ion transfer into and through mass spectrometers, enhanced-yield preparative mass separations, and mass filtering at the atmospheric pressure interface. In this study, an instrument was configured to allow for the performance characterization of a rectilinear ion trap (RIT) at pressures up to 50 mtorr with air used as the buffer gas. The mass analysis efficiency, mass resolution, isolation efficiency, and collision-induced dissociation (CID) efficiency were evaluated at pressures ranging from 1 to 50 mtorr. The extent of degradation of mass resolution, isolation efficiency and ion stability as functions of pressure were characterized. Also, the optimal resonance ejection conditions were obtained at various pressures. Operations at 50 mtorr demonstrated improved CID efficiency in addition to peak widths of 2 and 5 m/z units (full width at half-maximum, FWHM) for protonated caffeine (m/z 195) and Ultramark (m/z 1521) respectively.

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Section: Resultsmentioning

confidence: 99%

Ion trap mass analysis at high pressure: an experimental characterization

Song¹,

Xu²,

Smith³

et al. 2009

J. Mass Spectrom.

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“…Physical phenomena involved in electrosprays (such as production of charges and transport) can be complex 6, 23, 24. In the second part of the paper, the droplet formation in the capillary needle prior to the application of an electric field is also investigated.…”

Section: Resultsmentioning

confidence: 99%

Multi‐Scale Investigation of a Colloid Micro‐Propulsion System

Morris

Forget

Malardier-Jugroot

et al. 2011

Plasma Processes & Polymers

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IntroductionElectric propulsion is an advanced form of spacecraft propulsion which has many advantages over traditional counterparts. This propulsion device can be useful for satellites for the purpose of station-keeping, attitude control and possibly de-orbiting at end-of-life to reduce space debris. Advanced electric propulsion has also been demonstrated to be highly efficient for both commercial and military satellites. Indeed, electrostatic propulsion exhibits high specific impulse. i.e., exhaust velocity is very high. The thrust is relatively small but the combined effect of an electric propulsion system leads to significant reductions in propellant usage and enhanced lifetime. To illustrate, a relatively small force kept constant for a long period of time produces a relatively large velocity over time. The Tsiolkovsky equation encapsulates the advantages of electric propulsion: Dv ¼ v e lnðm i =m f Þ; where Dv is the change in velocity of the spacecraft, v e the mass-averaged value of the propellant exhaust velocity and m i and m f are the spacecraft masses before and after the thrusting event, respectively. It is clear from this equation that ambitious missions (i.e., for substantial changes in vehicle velocity), will necessitate a very large initial to final vehicle mass ratio

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“…However, focusing ions at atmospheric pressure toward a vacuum aperture using only dc fields is counteracted by Gauss’s law and the subsequent divergence of ion trajectories on the vacuum side of a simple aperture . It has been reported that the vacuum drag force due to the pressure gradient dominates over the effects of electric fields in the vicinity of a sampling capillary inlet. , In other words, optimizing the geometry in the region between the ablation site and the sampling inlet is crucial for sampling ions efficiently. In both scanning AP MALDI-MS and AP LDI-MS, the transport of ions through the metal capillary of a linear trap quadrupole (LTQ) mass spectrometer is limited by space-charge effects, which is of course not an issue for neutral molecules.…”

Section: Resultsmentioning

confidence: 99%

Atmospheric Pressure Sampling for Laser Ablation Based Nanoscale Imaging Mass Spectrometry: Ions or Neutrals?

et al. 2010

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Although the ratio of neutrals-to-ions in a typical laser ablation event was reported to be on the order of 1000 or greater, most imaging mass spectrometry (IMS) studies collect the minor ionic component instead of the abundant neutrals for subsequent mass analysis. In this report, we present a fundamentally different strategy, sampling neutrals from atmospheric pressure laser ablation into the vacuum of the mass spectrometer, followed by postionization, and mass spectrometric analysis. We compare its overall sampling efficiency (transfer efficiency + ionization efficiency) with that of ion sampling. The products from many single ablation events (creating a crater of ∼1 µm in diameter each) were deposited on a collection plate placed on the vacuum side of the sampling capillary. The sample surface and the collection plate were carefully examined both prior to and after laser ablation with scanning electron microscopy (SEM) and scanning probe microscopy (SPM). Volumetric measurements gave an estimate of the sampling efficiency of (1 ( 0.7) × 10 -4 overall. It was found that with a proper collection geometry, ablated neutral molecules can be efficiently directed to the inlet of the sampling capillary: several % are available for further MS analysis. We observed that the fraction of the ablated mass that leaves the sample in the form of particles was not sampled into the vacuum but was instead deposited between the ablation site and the capillary inlet. By comparing our results with those of other IMS techniques using ion sampling, we conclude that the overall sampling efficiencies are similar. Advantages provided by the neutral sampling approach include a large amount of analyte available for collection, the potential for improving the ionization efficiency, and the elimination of sample pretreatment steps.

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Coupled gas and ion transport in quadrupole interfaces

Cited by 16 publications

References 30 publications

Ion trap mass analysis at high pressure: an experimental characterization

Ion trap mass analysis at high pressure: an experimental characterization

Multi‐Scale Investigation of a Colloid Micro‐Propulsion System

Atmospheric Pressure Sampling for Laser Ablation Based Nanoscale Imaging Mass Spectrometry: Ions or Neutrals?

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