Analysis of harmonics for an elongated FTMS cell with multiple electrode detection

Nikolaev, E. N.; Rakov, V. Sergey

doi:10.1016/s0168-1176(96)04457-6

Cited by 27 publications

(19 citation statements)

References 7 publications

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“…It also provides a simple approach to the treatment of ICR signal harmonics. 26 Few simulations have been published on large populations of coulombically interacting particles in ICR mass spectrometers. The role of ion-ion interaction and image charge was first described by Talroze and Nikolaev 19 in connection with mass difference measurements of the 3 He/T doublet.…”

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confidence: 99%

Realistic modeling of ion cloud motion in a Fourier transform ion cyclotron resonance cell by use of a particle‐in‐cell approach

Nikolaev

Heeren

Popov

et al. 2007

Rapid Comm Mass Spectrometry

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Using a 'Particle-In-Cell' approach taken from plasma physics we have developed a new threedimensional (3D) parallel computer code that today yields the highest possible accuracy of ion trajectory calculations in electromagnetic fields. This approach incorporates coulombic ion-ion and ion-image charge interactions into the calculation. The accuracy is achieved through the implementation of an improved algorithm (the so-called Boris algorithm) that mathematically eliminates cyclotron motion in a magnetic field from digital equations for ion motion dynamics. It facilitates the calculation of the cyclotron motion without numerical errors. At every time-step in the simulation the electric potential inside the cell is calculated by direct solution of Poisson's equation. Calculations are performed on a computational grid with up to 128 T 128 T 128 nodes using a fast Fourier transform algorithm. The ion populations in these simulations ranged from 1000 up to 1 000 000 ions. A maximum of 3 000 000 time-steps were employed in the ion trajectory calculations. This corresponds to an experimental detection time-scale of seconds. In addition to the ion trajectories integral time-domain signals and mass spectra were calculated. The phenomena observed include phase locking of particular m/z ions (high-resolution regime) inside larger ion clouds. A focus was placed on behavior of a cloud of ions of a single m/z value to understand the nature of Fourier transform ion cyclotron resonance (FTICR) resolution and mass accuracy in selected ion mode detection. The behavior of two and three ion clouds of different but close m/z was investigated as well. Peak coalescence effects were observed in both cases. Very complicated ion cloud dynamics in the case of three ion clouds was demonstrated. It was found that magnetic field does not influence phase locking for a cloud of ions of a single m/z. The ion cloud evolution time-scale is inversely proportional to magnetic field. The number of ions needed for peak coalescence depends quadratically on the magnetic field. Copyright # 2007 John Wiley & Sons, Ltd.The leading role Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) plays in biological mass spectrometry is directly related to its unsurpassed resolution and mass accuracy combined with the possibility of utilizing all known ionization and fragmentation methods. Further improvement of mass accuracy will be greatly facilitated by a more detailed understanding of the motion of ions during ion introduction into the FTICR cell, excitation of their cyclotron motion, fragmentation and detection of induced signal. Starting from the early days of FTICR-MS the theory of ion motion in the ICR cell was an important research topic in this field. The dynamics of single particles inside the FTICR trap was analyzed by many groups in both the FTICR and physics communities. [1][2][3][4][5][6][7][8] The FTICR community has been interested mainly in obtaining a calibration formula, which connects measured frequency with ion mass. 9 The e...

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confidence: 99%

Realistic modeling of ion cloud motion in a Fourier transform ion cyclotron resonance cell by use of a particle‐in‐cell approach

Nikolaev

Heeren

Popov

et al. 2007

Rapid Comm Mass Spectrometry

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“…Signal detection at multiples of ion (reduced) cyclotron frequency, which is a feasible approach for increasing the throughput [32][33][34][35][36], is also limited by the design of those cells: they also comprise relatively wide aperture excitation and detection electrodes, resulting in a restricted factor of the generated multiples (e.g.,~22°electrodes and the fourth multiple for a 16-electrode ICR cell). A number of attempts have been made to reduce the aperture of detection electrodes.…”

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confidence: 99%

Ion Trap with Narrow Aperture Detection Electrodes for Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Nagornov

Kozhinov

Tsybin

et al. 2015

J. Am. Soc. Mass Spectrom.

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Abstract. The current paradigm in ion trap (cell) design for Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) is the ion detection with wide aperture detection electrodes. Specifically, excitation and detection electrodes are typically 90°wide and positioned radially at a similar distance from the ICR cell axis. Here, we demonstrate that ion detection with narrow aperture detection electrodes (NADEL) positioned radially inward of the cell's axis is feasible and advantageous for FT-ICR MS. We describe design details and performance characteristics of a 10 T FT-ICR MS equipped with a NADEL ICR cell having a pair of narrow aperture (flat) detection electrodes and a pair of standard 90°excitation electrodes. Despite a smaller surface area of the detection electrodes, the sensitivity of the NADEL ICR cell is not reduced attributable to improved excite field distribution, reduced capacitance of the detection electrodes, and their closer positioning to the orbits of excited ions. The performance characteristics of the NADEL ICR cell are comparable with the state-of-the-art FT-ICR MS implementations for small molecule, peptide, protein, and petroleomics analyses. In addition, the NADEL ICR cell's design improves the flexibility of ICR cells and facilitates implementation of advanced capabilities (e.g., quadrupolar ion detection for improved mainstream applications). It also creates an intriguing opportunity for addressing the major bottleneck in FTMS-increasing its throughput via simultaneous acquisition of multiple transients or via generation of periodic non-sinusoidal transient signals.

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“…Here, the recorded signal also deviates from an ideal cosine function since the ion does not move on a perfect circular orbit around the geometric axis of the ICR cell. Particularly, a magnetron motion in the ICR cell introduces sidebands to all harmonic peaks as well as to the fundamental peak [20,21]. In a regular FT-ICR spectrum, the abundance of harmonic signals is small but the harmonics have been a subject of interest for almost two decades.…”

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confidence: 99%

“…For example, by measuring the second harmonic (twice the fundamental cyclotron frequency), the resolving power can be doubled [23,25]. A detailed work studying and calculating harmonics has been published by Nikolaev et al [20]. In this work, multiple-electrode detections were suggested in an elongated FTMS cell for selectively detecting the higher harmonics spectra.…”

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confidence: 99%

“…In this work, multiple-electrode detections were suggested in an elongated FTMS cell for selectively detecting the higher harmonics spectra. Harmonic detection can also be used for improvements in signal-to-noise ratio in the high mass region [11,20]. The second category aims to measure the unperturbed cyclotron frequency from the detection of multiple frequencies, as the ideal unperturbed cyclotron frequency can be directly read from magnetron sidebands (ν + + ν − ) as described by Schweikhard et al [26,27], Allemann et al [28], and Miladinovic et al [29].…”

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confidence: 99%

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Tracking the Magnetron Motion in FT-ICR Mass Spectrometry

Jertz

Friеdrich

Kriete

et al. 2015

J. Am. Soc. Mass Spectrom.

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Abstract. In Fourier transform ion cyclotron resonance spectrometry (FT-ICR MS) the ion magnetron motion is not usually directly measured, yet its contribution to the performance of the FT-ICR cell is important. Its presence is manifested primarily by the appearance of even-numbered harmonics in the spectra. In this work, the relationship between the ion magnetron motion in the ICR cell and the intensities of the second harmonic signal and its sideband peak in the FT-ICR spectrum is studied. Ion motion simulations show that during a cyclotron motion excitation of ions which are offset to the cell axis, a position-dependent radial drift of the cyclotron center takes place. This radial drift can be directed outwards if the ion is initially offset towards one of the detection electrodes, or it can be directed inwards if the ion is initially offset towards one of the excitation electrodes. Consequently, a magnetron orbit diameter can increase or decrease during a resonant cyclotron excitation. A method has been developed to study this behavior of the magnetron motion by acquiring a series of FT-ICR spectra using varied post-capture delay (PCD) time intervals. PCD is the delay time after the capture of the ions in the cell before the cyclotron excitation of the ion is started. Plotting the relative intensity of the second harmonic sideband peak versus the PCD in each mass spectrum leads to an oscillating BPCD curve". The position and height of minima and maxima of this curve can be used to interpret the size and the position of the magnetron orbit. Ion motion simulations show that an off-axis magnetron orbit generates even-numbered harmonic peaks with sidebands at a distance of one magnetron frequency and multiples of it. This magnetron offset is due to a radial offset of the electric field axis versus the geometric cell axis. In this work, we also show how this offset of the radial electric field center can be corrected by applying appropriate DC correction voltages to the mantle electrodes of the ICR cell while observing the signals of the second harmonic peak group. The field correction leads to a definite performance increase in terms of resolving power and mass accuracy, and the mass spectrum contains intensity-minimized even-numbered harmonics. This is very important in the case of high performance cells, particularly the dynamically harmonized cell, since the magnetron motion can severely impair the averaging effect for dynamic harmonization and can therefore reduce the resolving power.

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Analysis of harmonics for an elongated FTMS cell with multiple electrode detection

Cited by 27 publications

References 7 publications

Realistic modeling of ion cloud motion in a Fourier transform ion cyclotron resonance cell by use of a particle‐in‐cell approach

Realistic modeling of ion cloud motion in a Fourier transform ion cyclotron resonance cell by use of a particle‐in‐cell approach

Ion Trap with Narrow Aperture Detection Electrodes for Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Tracking the Magnetron Motion in FT-ICR Mass Spectrometry

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