Excitation of the z-motion of ions in a cubic icr cell

Hart, W.J. van der; Guchte, W.J. van de

doi:10.1016/0168-1176(88)80002-8

Cited by 75 publications

(28 citation statements)

References 8 publications

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“…It has been well recognized that a dipolar burst excitation field whose frequency is ω z or ω + + 2ω z can resonantly excite the trapping oscillation. 16 However, our simulation result does not look like the burst excitation case.…”

Section: Off-resonance Dynamics Of Ions During Broadband Excitationscontrasting

confidence: 43%

Non-linear Effects on Fourier Transform Ion Cyclotron Resonance Mass Spectra Induced by Off-resonance Excitations

Naito

Inoue

1997

Rapid Commun. Mass Spectrom.

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Computer simulation studies were made to analyse the behavior of ions under broadband excitation in a cylindrical FTICR ion trap. The mechanism of off-resonance excitation of ions was investigated by displaying the tangential components of the Lorentz force and phase diagram. It was found that a combination of the off-resonance effect with the inhomogeneity of an RF excitation field causes incidental z-ejection of trapped ions. © 1997 by John Wiley & Sons, Ltd. Received 18 November 1996; Revised 8 February 1997; Accepted 12 February 1997 Rapid. Commun. Mass Spectrom. 11, 578-586 (1997 In Fourier transform ion cyclotron resonance (FTICR) mass spectrometry, detection of ions is performed first by coherently accelerating ions to larger cyclotron orbits (excitation) and second by sensing alternating image currents induced on the detection circuit.1,2 This 'indirect' or 'non-destructive' detection enables the same batch of ions to be measured repeatedly so as to improve mass resolving power and sensitivity [3][4][5][6][7] or to be used to execute multiple tandem mass spectrometric (MS n ) experiments without consuming a large amount of sample.8 This indirect ion detection is one of the notable features of FTICR mass spectrometry; however, the intensity of the detected signal is strongly dependent upon the ICR excitation processes. To establish quantitative accuracy and reproducibility in FTICR ions should be accelerated to well defined orbits. 9The motion of RF-irradiated ions in an FTICR ion trap can be treated approximately by expanding analytical forms of the electric potential in the ion trap up to some orders in Cartesian coordinates. The first-order approximation is the simplest case which results in motion in a spatially uniform excitation field where the ion cyclotron radius is linearly proportional to the excitation magnitude 10,11 and the relative positions of ions in the coherent packet do not change during the excitation period.12 This approximation scheme corresponds to an RF field generated by a pair of infinitely extended parallel excitation electrodes. However, in a real FTICR ion trap, the configuration of the electric field is far from such an idealized model. The solution which takes account of the fourth-order expansion for the RF potential already brings in the coupling of axial and radial ion motion at the bipolar radial excitation frequencies of 2ω z and ω + + 2 ω z , [13][14][15][16][17][18][19][20] in which ω z and ω + denote the axial-trapping oscillation frequency and the effective ion cyclotron frequency in the inhomogeneous trapping electric field, respectively. These 'unfavorable' resonances may accelerate ions toward trapping plates and result in eventual loss of ions. This 'z-ejection' phenomenon is thought to cause a mass discrimination effect under certain experimental conditions. 13With the development of high-performance computers, the ICR excitation processes have been studied numerically with these computers rather than analytically. Xiang and Marshall 20 calculated the ion traj...

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Section: Off-resonance Dynamics Of Ions During Broadband Excitationscontrasting

confidence: 43%

Non-linear Effects on Fourier Transform Ion Cyclotron Resonance Mass Spectra Induced by Off-resonance Excitations

Naito

Inoue

1997

Rapid Commun. Mass Spectrom.

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“…However, the TREC design is compatible with the Infinity Cell45 concept or a similar approach where excitation has been coupled to the segmented trap plates. Integrating the TREC concept with excitation coupled to the trapping ring electrodes would address z -axis ejection46 and linearize the excitation profile (Supplemental Figures 3 and 4, Supporting Information), while retaining the ability to moderate the radial electric fields during detection.…”

Section: Resultsmentioning

confidence: 99%

Trapping Ring Electrode Cell: A FTICR Mass Spectrometer Cell for Improved Signal-to-Noise and Resolving Power

et al. 2008

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A novel FTICR cell called the trapping ring electrode cell (TREC) has been conceived, simulated, developed, and tested. The performance of the TREC is compared to a closed cylindrical cell at different excited cyclotron radii. The TREC permits the ability to maintain coherent ion motion at larger initial excited cyclotron radii by decreasing the change in radial electric field with respect to z-axis position in the cell. This is accomplished through postexcitation modulation of the trapping potentials applied to segmented trap plates. Resolving power approaching the theoretical limit was achieved using the novel TREC technology; over 420 000 resolving power was observed on melittin [M + 4H] 4+ species when employed under modest magnetic field strength (3T) and a data acquisition duration of 13 s. A 10-fold gain in signal-to-noise ratio is demonstrated over the closed cylindrical cell optimized with common potentials on all ring electrodes. The observed frequency drift during signal acquisition over long time periods was also significantly reduced, resulting in improved resolving power.Fourier transform ion cyclotron resonance mass spectrometry 1 (FTICR-MS) provides high resolution, mass measurement accuracy, and sensitivity which makes it ideally suited for analytical application in the areas of proteomics, 2-4 metabolomics,5 petroleomics,6 ,7 and many others. FTICR-MS is the high performance end of proteomics research today, with the capability to identify proteins and protein-protein interactions based on accurate mass measurements. [8][9][10] In general, the more accurately a mass can be determined, the more confident identification can be assigned for a given protein 11,12 and the more confidently unknown peptide sequences can be determined. 13 The goal to apply mass spectrometry to ever-increasingly complex biological samples furthers the demand for increased analytical capabilities and the need for development of higher performance instrumentation.The FTICR mass spectrometer relies upon an electromagnetic ion trap or cell to confine ions during detection. 14-16 The confinement is accomplished radially (x-y dimension) by an applied magnetic field parallel to the z-axis of the ion trap and axially using DC electrical potentials applied to trapping electrodes. As an ion approaches either trap plate, it experiences a force due to the electric field, and its kinetic energy is converted to potential energy. Thus, the ion exhibits periodic motion similar to the classical harmonic oscillator. As a consequence of the method by which ions are trapped within the cell, four natural motions arise. Trapping oscillation is the motion in which the ions oscillate in the zdimension of the cell. Cyclotron motion is caused by the Lorentz force and is dependent upon the mass-to-charge ratio (m/z) (eq 1).

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“…For this reaction, ions were formed by electron ionization and then allowed a "relaxation period", usually around 100 ms, during which they underwent approximately 10 ion-molecule collisions, lost excess kinetic energy, and relaxed along the z (magnetic field) axis to the center of the FTICR cell, where detection efficiency has been shown to be the highest [33,34]. This relaxation period precludes the observation of any kinetic energy or electronic energy effects on the reactivity of Ar t ions during the first 100 ms after ion formation.…”

Section: Methodsmentioning

confidence: 99%

Probing trapped ion energies via ion-molecule reaction kinetics: Fourier transform ion cyclotron resonance mass spectrometry

Bruce

Eyler

1992

J. Am. Soc. Mass Spectrom.

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Excitation of the z-motion of ions in a cubic icr cell

Cited by 75 publications

References 8 publications

Non-linear Effects on Fourier Transform Ion Cyclotron Resonance Mass Spectra Induced by Off-resonance Excitations

Non-linear Effects on Fourier Transform Ion Cyclotron Resonance Mass Spectra Induced by Off-resonance Excitations

Trapping Ring Electrode Cell: A FTICR Mass Spectrometer Cell for Improved Signal-to-Noise and Resolving Power

Probing trapped ion energies via ion-molecule reaction kinetics: Fourier transform ion cyclotron resonance mass spectrometry

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